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Dharmaraja, S., K. S. Trivedi und D. Logothetis. „Performance modeling of wireless networks with generally distributed handoff interarrival times“. Computer Communications 26, Nr. 15 (September 2003): 1747–55. http://dx.doi.org/10.1016/s0140-3664(03)00044-6.
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Espinosa, Luis Angel, Maria Manuela Portela, João Dehon Pontes Filho, Ticiana Marinho de Carvalho Studart, João Filipe Santos und Rui Rodrigues. „Jointly Modeling Drought Characteristics with Smoothed Regionalized SPI Series for a Small Island“. Water 11, Nr. 12 (26.11.2019): 2489. http://dx.doi.org/10.3390/w11122489.
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The paper refers to a study on droughts in a small Portuguese Atlantic island, namely Madeira. The study aimed at addressing the problem of dependent drought events and at developing a copula-based bivariate cumulative distribution function for coupling drought duration and magnitude. The droughts were identified based on the Standardized Precipitation Index (SPI) computed at three and six-month timescales at 41 rain gauges distributed over the island and with rainfall data from January 1937 to December 2016. To remove the spurious and short duration-dependent droughts a moving average filter (MA) was used. The run theory was applied to the smoothed SPI series to extract the drought duration, magnitude, and interarrival time for each drought category. The smoothed series were also used to identify homogeneous regions based on principal components analysis (PCA). The study showed that MA is necessary for an improved probabilistic interpretation of drought analysis in Madeira. It also showed that despite the small area of the island, three distinct regions with different drought temporal patterns can be identified. The copulas approach proved that the return period of droughts events can differ significantly depending on the way the relationship between drought duration and magnitude is accounted for.
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Montoro-Cazorla, Delia, und Rafael Pérez-Ocón. „Analysis of k-Out-of-N-Systems with Different Units under Simultaneous Failures: A Matrix-Analytic Approach“. Mathematics 10, Nr. 11 (02.06.2022): 1902. http://dx.doi.org/10.3390/math10111902.
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An N-system with different units submitted to shock and wear is studied. The shocks cause damage and, eventually, simultaneous failures of several units. The units can also fail due to internal failures. At random times, the system is inspected, and the down units are simultaneously replaced by identical ones. The arrival of shocks is governed by a Markovian arrival process. The operational times and the interarrival times between inspections follow phase-type distributions. The generator of the multidimensional Markov process modeling the system is constructed. This is performed introducing indicator functions for the different transition rates among the units using the algorithm of Kronecker. This is a general Markov process that can be applied for modeling different reliability systems depending on the structure of the units and how the systems operate. The general model is applied to the study of k-out-of-N systems, calculating the main performance measures. A practical example is presented showing the approximation of the model to a system with units following different Weibull distributions.
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Baiamonte, Giorgio, Carmelo Agnese, Carmelo Cammalleri, Elvira Di Nardo, Stefano Ferraris und Tommaso Martini. „Applying different methods to model dry and wet spells at daily scale in a large range of rainfall regimes across Europe“. Advances in Statistical Climatology, Meteorology and Oceanography 10, Nr. 1 (22.03.2024): 51–67. http://dx.doi.org/10.5194/ascmo-10-51-2024.
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Abstract. The modeling of the occurrence of a rainfall dry spell and wet spell (ds and ws, respectively) can be jointly conveyed using interarrival times (its). While the modeling has the advantage of requiring a single fitting for the description of all rainfall time characteristics (including wet and dry chains, an extension of the concept of spells), the assumption of the independence and identical distribution of the renewal times it implicitly imposes a memoryless property on the derived ws, which may not be true in some cases. In this study, two different methods for the modeling of rainfall time characteristics at the station scale have been applied: (i) a direct method (DM) that fits the discrete Lerch distribution to it records and that then derives ws and ds (as well as the corresponding chains) from the it distribution and (ii) an indirect method (IM) that fits the Lerch distribution to the ws and ds records separately, relaxing the assumptions of the renewal process. The results of this application over six stations in Europe, characterized by a wide range of rainfall regimes, highlight how the geometric distribution does not always reasonably reproduce the ws frequencies, even when its are modeled well by the Lerch distribution. Improved performances are obtained with the IM thanks to the relaxation of the assumption of the independence and identical distribution of the renewal times. A further improvement of the fittings is obtained when the datasets are separated into two periods, suggesting that the inferences may benefit from accounting for the local seasonality.
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HADJI, Sofiane. „A coupled models Hydrodynamics - Multi headed Deep convolutional neural network for rapid forecasting large-scale flood inundation“. International Journal of Engineering and Computer Science 10, Nr. 11 (21.11.2021): 25420–30. http://dx.doi.org/10.18535/ijecs/v10i11.4636.
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Modeling large-scale flood inundation requires weeks of calculations using complex fluid software. The state-of-the-art in operational hydraulic modeling does not currently allow flood real-time forecasting fields. Data driven models have small computational costs and fast computation times and may be useful to overcome this problem. In this paper, we propose a new modeling approach based on a coupled of Hydrodynamics finite element model and Multi-headed Deep convolutional neural network (MH-CNN) with rain precipitations as input to forecast rapidly the water depth reached in large floodplain with few hours-ahead. For this purpose, one first builds a database containing different simulations of the physical model according to several rain precipitation scenarios (historic and synthetic). The multi-headed convolutional neural network is then trained using the constructed database to predict water depths. The pre-trained model is applied successfully to simulate the real July 2014 flood inundation in an 870 km2 area of La Nive watershed in the south west of France. Because rain precipitation forecast data is more accessible than discharge one, this approach offers great potential for real-time flood modelling for ungauged large-scale territories, which represent a large part of floodplain in the world.
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Schleiss, Marc. „Scaling and Distributional Properties of Precipitation Interamount Times“. Journal of Hydrometeorology 18, Nr. 4 (01.04.2017): 1167–84. http://dx.doi.org/10.1175/jhm-d-16-0221.1.
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Abstract The scaling and distributional properties of precipitation interamount times (IATs) are investigated using 10 years of high-resolution rain gauge observations from the U.S. Climate Reference Network. Results show that IATs above 200 mm tend to be approximately uncorrelated and normally distributed. As one moves toward smaller scales, autocorrelation and skewness increase and distributions progressively evolve into Weibull, Gamma, lognormal, and Pareto. This procession is interpreted as a sign of increasing complexity from large to small scales in a system composed of many interacting components. It shows that, as one approaches finer scales, IATs take over more of the characteristics of power-law distributions and (multi)fractals. Regression analysis on the log moments reveals that IATs generally exhibit better scaling, that is, smaller departures from multifractality, than precipitation amounts over the same range of scales. The improvement is attributed to the fact that IATs, unlike rainfall rates, always remain positive, no matter how small the scale. In particular, the scaling is shown to be more resilient to dry periods within rain events. Nevertheless, most analyzed IAT time series still exhibited a breakpoint at about 20 mm (7 days), corresponding to the average lifetime of a low pressure system at midlatitudes. Additional breakpoints in IATs at smaller and larger time scales are possible, but could not be determined unambiguously. The results highlight the potential of IATs as a new and promising tool for the stochastic modeling, simulation, and downscaling of precipitation.
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KRISHNAMURTI, T. N., T. S. V. VIJAYA KUMAR, BRIAN MACKEY, NIHAT CUBUCKU und ROBERT S. ROSS. „Current thrusts on TRMM and SSM/I based modeling studies on heavy rains and flooding episodes“. MAUSAM 54, Nr. 1 (18.01.2022): 121–40. http://dx.doi.org/10.54302/mausam.v54i1.1497.
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Our research group at the Florida State University has been using a multianalysis/multimodel approach on real time for the short-range prediction of heavy rains over the tropical belt. The methodology for the construction of the superensemble forecasts follows our recent publications on this topic. Recent improvements in multianalysis/multimodel superensemble forecasts of precipitation have led to much higher skills compared to the member models. This suggested that some useful guidance for regional floods arising from heavy rains might be possible from this approach. These are 1 to 5 day forecasts where the equitable threat scores for rainfall totals in excess of 25 mm/day have been two to three times better for the superensemble compared to the best member model. This study includes forecasts using multimodels from a number of global operational centers and a multianalysis component, which is based on the FSU global spectral model that utilizes TRMM and SSM/I data sets and a number of rain rate algorithms. The differences in the analyses arise from the use of these different rain rate algorithms within physical initialization, which in turn, produces distinct differences among divergence, heating, moisture, and rain rate descriptions. A total of 11 models, of which 5 represent global operational models and 6 represent multianalysis forecasts from the FSU model initialized by different rain rate algorithms, are embedded in the multianalysis/multimodel system studied here. The TRMM and the SSM/I rainfall data sets derived from microwave instruments are key to these marked improvements of rainfall forecasts. The statistical biases of the models are determined from a multiple linear regression of these forecasts against a ‘best’ rainfall analysis field, which is based on a TRMM and SSM/I data set that utilizes rain rate algorithms recently developed at NASA Goddard. We also display a sequence of computations that illustrate a “walk-through” of a heavy rain episode. This study specifically deals with recent flood episodes over India, Bangladesh, the United States of America, Mozambique/Madagascar and the Philippines. These results compare the performance of the superensemble against the best and lowest performing model, the ensemble mean and the control experiment (that does not use any TRMM or SSM/I data sets). Overall these results show great promise over the current best models.
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Helalia, Sarah A., Ray G. Anderson, Todd H. Skaggs und Jirka Šimůnek. „Impact of Drought and Changing Water Sources on Water Use and Soil Salinity of Almond and Pistachio Orchards: 2. Modeling“. Soil Systems 5, Nr. 4 (24.09.2021): 58. http://dx.doi.org/10.3390/soilsystems5040058.
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California is increasingly experiencing drought conditions that restrict irrigation deliveries to perennial nut crops such as almonds and pistachios. During drought, poorer quality groundwater is often used to maintain these crops, but this use often results in secondary salinization that requires skilled management. Process-based models can help improve management guidelines under these challenging circumstances. The main objective of this work was to assess seasonal soil salinity and root water uptake as a function of irrigation water salinity and annual rain amounts. The manuscript presents a comparison of three-year experimental and numerically simulated root zone salinities in and below the root zone of almond and pistachio drip-irrigated orchards at multiple locations in the San Joaquin Valley (SJV), California, with different meteorological characteristics. The HYDRUS-1D numerical model was calibrated and validated using field measurements of soil water contents and soil solute bulk electrical conductivities at four root zone depths and measured soil hydraulic conductivities. The remaining soil hydraulic parameters were estimated inversely. Observations and simulations showed that the effects of rain on root zone salinity were higher in fields with initially low salinities than in fields with high salinities. The maximum reduction in simulated root water uptake (7%) occurred in response to initially high soil salinity conditions and saline irrigation water. The minimum reduction in simulated water uptake (2.5%) occurred in response to initially low soil salinity conditions and a wet rain year. Simulated water uptake reductions and leaching fractions varied at early and late times of the growing season, depending on irrigation water salinity. Root water uptake reduction was highly correlated with the cumulative effects of using saline waters in prior years, more than salt leaching during a particular season, even when rain was sufficient to leach salts during a wet year.
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Grabowski, Wojciech W., und Hugh Morrison. „Modeling Condensation in Deep Convection“. Journal of the Atmospheric Sciences 74, Nr. 7 (29.06.2017): 2247–67. http://dx.doi.org/10.1175/jas-d-16-0255.1.
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Abstract Cloud-scale models apply two drastically different methods to represent condensation of water vapor to form and grow cloud droplets. Maintenance of water saturation inside liquid clouds is assumed in the computationally efficient saturation adjustment approach used in most bulk microphysics schemes. When super- or subsaturations are allowed, condensation/evaporation can be calculated using the predicted saturation ratio and (either predicted or prescribed) mean droplet radius and concentration. The study investigates differences between simulations of deep unorganized convection applying a saturation adjustment condensation scheme (SADJ) and a scheme with supersaturation prediction (SPRE). A double-moment microphysics scheme with CCN activation parameterized as a function of the local vertical velocity is applied to compare cloud fields simulated applying SPRE and SADJ. Clean CCN conditions are assumed to demonstrate upper limits of the SPRE and SADJ difference. Microphysical piggybacking is used to extract the impacts with confidence. Results show a significant impact on deep convection dynamics, with SADJ featuring more cloud buoyancy and thus stronger updrafts. This leads to around a 3% increase of the surface rain accumulation in SADJ. Upper-tropospheric anvil cloud fractions are much larger in SPRE than in SADJ because of the higher ice concentrations and thus longer residence times of anvil particles in SPRE, as demonstrated by sensitivity tests. Higher ice concentrations in SPRE come from significantly larger ice supersaturations in strong convective updrafts that feature water supersaturations of several percent.
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Kiewiet, Leonie, Ernesto Trujillo, Andrew Hedrick, Scott Havens, Katherine Hale, Mark Seyfried, Stephanie Kampf und Sarah E. Godsey. „Effects of spatial and temporal variability in surface water inputs on streamflow generation and cessation in the rain–snow transition zone“. Hydrology and Earth System Sciences 26, Nr. 10 (01.06.2022): 2779–96. http://dx.doi.org/10.5194/hess-26-2779-2022.
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Abstract. Climate change affects precipitation phase, which can propagate into changes in streamflow timing and magnitude. This study examines how the spatial and temporal distribution of rainfall and snowmelt affects discharge in rain–snow transition zones. These zones experience large year-to-year variations in precipitation phase, cover a significant area of mountain catchments globally, and might extend to higher elevations under future climate change. We used observations from 11 weather stations and snow depths measured from one aerial lidar survey to force a spatially distributed snowpack model (iSnobal/Automated Water Supply Model) in a semiarid, 1.8 km2 headwater catchment. We focused on surface water input (SWI; the summation of rainfall and snowmelt on the soil) for 4 years with contrasting climatological conditions (wet, dry, rainy, and snowy) and compared simulated SWI to measured discharge. A strong spatial agreement between snow depth from the lidar survey and model (r2 = 0.88) was observed, with a median Nash–Sutcliffe efficiency (NSE) of 0.65 for simulated and measured snow depths at snow depth stations for all modeled years (0.75 for normalized snow depths). The spatial pattern of SWI was consistent between the 4 years, with north-facing slopes producing 1.09–1.25 times more SWI than south-facing slopes, and snowdrifts producing up to 6 times more SWI than the catchment average. Annual discharge in the catchment was not significantly correlated with the fraction of precipitation falling as snow; instead, it was correlated with the magnitude of precipitation and spring snow and rain. Stream cessation depended on total and spring precipitation, as well as on the melt-out date of the snowdrifts. These results highlight the importance of the heterogeneity of SWI at the rain–snow transition zone for streamflow generation and cessation, and emphasize the need for spatially distributed modeling or monitoring of both snowpack and rainfall dynamics.
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Chernogor, L. F., A. N. Nekos, G. V. Titenko und L. L. Chornohor. „Parameters and environmental consequences of catastrophic fires in Ukraine: modeling, quantitative estimates“. Man and Environment. Issues of Neoecology, Nr. 42 (28.11.2024): 83–94. https://doi.org/10.26565/1992-4224-2024-42-06.
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Climatic conditions and the intensification of hostilities in the east of Ukraine in 2024 (August and September) led to the burning of large areas of forests and grasslands. A quantitative assessment of their consequences is necessary. Methods. System analysis, multifactorial analysis, mathematical modeling. Purpose. Calculation of the main parameters of fires in the ecosystems of Ukraine, which took place in the summer-autumn of 2024, and assessment of their ecological consequences. The results. The main energy parameters of forest and grass fires caused by the summer heat and military operations in Ukraine in 2024 were calculated. In late August - early September, virtually the entire east of Ukraine was burning. A total of about 43,000 hectares were engulfed in flames in Ukraine. About 500 kt of wood and 350 kt of grass burned. Emissions of smoke, soot, and nitrogen oxides exceeded the background values of the masses of these substances many times over. The injection of polyaromatic hydrocarbons exceeded the background values by 570, PM 2.5 microparticles by 14 times, and the power of acoustic radiation by 30 times. CO, SOx emissions did not exceed several tens of percent. The spread of fires in ecosystems, in addition to military operations, was facilitated by high air temperature, lack of rain and wind. Conclusions. Calculations and mathematical modeling showed that the consequences of the burning of forests and grasslands in Ukraine in 2024 were catastrophic. It is substantiated that most of the fires were caused by military actions on the territory of Ukraine. The ecological situation became significantly more complicated under the influence of a dust storm that came from Kazakhstan and Central Asia. The short-term and long-term environmental consequences are very significant.
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Shahi, Aavas Jung, Madan Pokhrel und Shankar Lamichhane. „Urban Roadside Flooding Analysis Using SWMM: A Case Study of a Road Section in Pokhara Metropolitan City, Nepal“. Journal of Engineering and Sciences 3, Nr. 1 (04.06.2024): 36–44. http://dx.doi.org/10.3126/jes2.v3i1.66233.
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Pokhara City, in Nepal, experiences heavy rainfall during four months of monsoon, causing stress on drainage infrastructures. This situation is exacerbated by poor drainage systems, ineffective urban planning, and rapid urbanization. This study aims to develop mitigation strategies for urban roadside flooding in the Barahi Chowk region in Pokhara City. The focus is to identify the causes and potential solutions for the recurring issue of urban roadside flooding. For this purpose, the study utilizes Storm Water Management Model (SWMM) computer modeling to analyze the hydraulic capacity of existing drainage systems during peak flows. The SWMM modeling reveals that the current drainage usage is between 80% and 100% during peak times, leading to flooding. Consequently, resizing or expanding various drainage sections using SWMM modeling is suggested. The study introduces Low Impact Development (LID) controls, such as rain gardens and permeable pavements, to manage surface runoff. Implementing rain gardens on just 3% of the impervious area in each sub-catchment showed an average 21.5% reduction in peak runoff and an average 6.68% reduction in the total runoff while implementing 5% in each sub-catchment, permeable pavements reduced peak runoff by 22-26% and total runoff by 8-11%. The research explores the impact of land use and land cover change and unplanned urban growth on roadside flooding, resulting in impermeable urban surfaces that disturb the natural drainage system and infiltration pattern. Thus, the outcomes of this study should be carefully considered by policymakers and stakeholders to address issues through sustainable urban planning and infrastructure development. Also, implementing measures like resizing drains and LID controls appears to be effective in controlling flooding during the study period and should be considered for future studies as well.
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Santos, Maria Aparecida do Nascimento dos, Ildegardis Bertol, Danieli Schneiders Kaufmann, José Mecabô Júnior und Bárbara Bagio. „Rusle parameters for modeling the loss of a soil subjected to pig slurry application“. Pesquisa Agropecuária Brasileira 53, Nr. 10 (Oktober 2018): 1167–76. http://dx.doi.org/10.1590/s0100-204x2018001000010.
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Abstract: The objective of this work was to determine adjustment parameters for the revised universal soil loss equation (Rusle) of a soil subjected to pig slurry application. Treatments consisted of 0, 50, 100, and 200 m3 ha-1 pig slurry (PS), after the cultivation of black oat (Avena strigosa), besides the application of 50 m3 ha-1 PS for six times onto the soil surface in a temporal sequence, and a control treatment of soil without cultivation and without pig slurry application. The evaluations were performed for black oat shoot dry mass, root mass and crop residues semi-incorporated into the soil (RMR), soil losses by means of simulated rain, and the parameters for water erosion modeling. The pig slurry application onto soil surface caused a reduction in the values of the soil consolidation parameter (Cf), an increase in the mass of living and dead roots and cultural residues incorporated in the upper layer (0.0-0.1 m) of the soil (Bu), and a reduction in the subfactor prior land use (PLU) of the Rusle.
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Van Stan, John T., Ethan D. Gutmann, Elliott S. Lewis und Trent E. Gay. „Modeling Rainfall Interception Loss for an Epiphyte-Laden Quercus virginiana Forest Using Reformulated Static- and Variable-Storage Gash Analytical Models“. Journal of Hydrometeorology 17, Nr. 7 (01.07.2016): 1985–97. http://dx.doi.org/10.1175/jhm-d-16-0046.1.
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Abstract Barrier island forests are sensitive to changing precipitation characteristics as they typically rely on a precipitation-fed freshwater lens. Understanding and predicting significant rainfall losses is, therefore, critical to the prediction and management of hydrometeorological processes in the barrier island forest ecosystem. This study measures and models one such loss, canopy rainfall interception, for a barrier island forest common across subtropical and tropical coastlines: epiphyte-laden Quercus virginiana on St. Catherine’s Island (Georgia, United States). Reformulated Gash analytical models (RGAMs) relying on static- and variable-canopy-storage formulations were parameterized using common maximum water storage (minimum, mean, maximum, and laboratory submersion) and evaporation (Penman–Monteith, saturated rain–throughfall regression, and rain–interception regression) estimation methods. Cumulative interception loss was 37% of rainfall, and the epiphyte community contribution to interception loss was 11%. Variable-storage RGAMs using inferred evaporation and maximum water storage estimates performed best: mean absolute error of 1–2 mm, normalized mean percent error of 15%–25%, and model efficiency of 0.88–0.97, resulting in a 2%–5% overestimate of cumulative interception. Static- and variable-storage RGAMs using physically derived evaporation (Penman–Monteith) underestimated observed interception loss (40%–60%), yet the error was significantly lowered for submersion estimates of maximum water storage. Greater apparent error when using Penman–Monteith rates may result from unknown drying times, evaporation sources, and/or in situ epiphyte storage dynamics. As such, it is suggested that future research apply existing technologies to quantify evaporative processes during rainfall (e.g., eddy covariance) and to develop new methods to directly monitor in situ epiphyte water storage.
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Bruno, Leonardo Souza, Tiago Souza Mattos, Paulo Tarso Sanches Oliveira, André Almagro und Dulce Buchala Bicca Rodrigues. „Hydrological and Hydraulic Modeling Applied to Flash Flood Events in a Small Urban Stream“. Hydrology 9, Nr. 12 (09.12.2022): 223. http://dx.doi.org/10.3390/hydrology9120223.
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In flood area mapping studies, hydrological-hydraulic modeling has been successfully applied around the world. However, the object of study of most of the research developed in Brazil is medium to large channels that use topographical and hydrometeorological data of coarse spatial and temporal resolution. Thus, the aim of this study is to investigate coupled modeling in a small urban channel, using high-resolution data, in the simulation of flood events in a small urban channel, located in Campo Grande, Mato Grosso do Sul. In this study, we used the HEC-HMS and HEC-RAS programs, where topographic information, land use, land cover, and observed data from rain gauges, water level, and flow sensors from 2015 to 2018 were used as input data. To calibrate and validate the hydrological model, four events were used that occurred during the monitoring period, while in the hydraulic model we chose a historical event that caused great disturbances. We then generated flood scenarios with representative synthetic rainfall for a basin, with return times of 5, 10, 50, and 100 years. We observed a good fit in the calibration and validation of the HEC-HMS, with values of R2 = 0.93, RMSE = 1.29, and NSE = 0.92. In HEC-RAS, we obtained values of R2 = 0.93, RMSE = 1.29, and NSE = 0.92 for the calibration, and in the validation, real images of the event prove the computed flood spot sources. We observed that rain with a return time of less than five years provides areas of flooding in several regions of the channel, and in critical channeled sections, the elevation and speed of the flow reach 5 m and 3 m·s−1, respectively. Our results indicate that the channel already has a natural tendency towards flooding in certain stretches, which become more compromised due to land use and coverage and local conditions. We conclude that the high-resolution coupled modeling generated information that represents local conditions as well, showing how potential failures of drainage in extreme scenarios are possible, thus enabling the planning of adaptations and protection measures against floods.
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Lasher-Trapp, Sonia, Shailendra Kumar, Daniel H. Moser, Alan M. Blyth, Jeffrey R. French, Robert C. Jackson, David C. Leon und David M. Plummer. „On Different Microphysical Pathways to Convective Rainfall“. Journal of Applied Meteorology and Climatology 57, Nr. 10 (Oktober 2018): 2399–417. http://dx.doi.org/10.1175/jamc-d-18-0041.1.
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ABSTRACTThe Convective Precipitation Experiment (COPE) documented the dynamical and microphysical evolution of convection in southwestern England for testing and improving quantitative precipitation forecasting. A strong warm rain process was hypothesized to produce graupel quickly, initiating ice production by rime splintering earlier to increase graupel production and, ultimately, produce heavy rainfall. Here, convection observed on two subsequent days (2 and 3 August 2013) is used to test this hypothesis and illustrate how environmental factors may alter the microphysical progression. The vertical wind shear and cloud droplet number concentrations on 2 August were 2 times those observed on 3 August. Convection on both days produced comparable maximum radar-estimated rain rates, but in situ microphysical measurements indicated much less ice in the clouds on 2 August, despite having maximum cloud tops that were nearly 2 km higher than on 3 August. Idealized 3D numerical simulations of the convection in their respective environments suggest that the relative importance of particular microphysical processes differed. Higher (lower) cloud droplet number concentrations slow (accelerate) the warm rain process as expected, which in turn slows (accelerates) graupel formation. Rime splintering can explain the abundance of ice observed on 3 August, but it was hampered by strong vertical wind shear on 2 August. In the model, the additional ice produced by rime splintering was ineffective in enhancing surface rainfall; strong updrafts on both days lofted supercooled raindrops well above the 0°C level where they froze to become graupel. The results illustrate the complexity of dynamical–microphysical interactions in producing convective rainfall and highlight unresolved issues in understanding and modeling the competing microphysical processes.
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Barthlott, C., und C. Hoose. „Spatial and temporal variability of clouds and precipitation over Germany: multiscale simulations across the "gray zone"“. Atmospheric Chemistry and Physics 15, Nr. 21 (09.11.2015): 12361–84. http://dx.doi.org/10.5194/acp-15-12361-2015.
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Abstract. This paper assesses the resolution dependance of clouds and precipitation over Germany by numerical simulations with the COnsortium for Small-scale MOdeling (COSMO) model. Six intensive observation periods of the HOPE (HD(CP)2 Observational Prototype Experiment) measurement campaign conducted in spring 2013 and 1 summer day of the same year are simulated. By means of a series of grid-refinement resolution tests (horizontal grid spacing 2.8, 1 km, 500, and 250 m), the applicability of the COSMO model to represent real weather events in the gray zone, i.e., the scale ranging between the mesoscale limit (no turbulence resolved) and the large-eddy simulation limit (energy-containing turbulence resolved), is tested. To the authors' knowledge, this paper presents the first non-idealized COSMO simulations in the peer-reviewed literature at the 250–500 m scale. It is found that the kinetic energy spectra derived from model output show the expected −5/3 slope, as well as a dependency on model resolution, and that the effective resolution lies between 6 and 7 times the nominal resolution. Although the representation of a number of processes is enhanced with resolution (e.g., boundary-layer thermals, low-level convergence zones, gravity waves), their influence on the temporal evolution of precipitation is rather weak. However, rain intensities vary with resolution, leading to differences in the total rain amount of up to +48 %. Furthermore, the location of rain is similar for the springtime cases with moderate and strong synoptic forcing, whereas significant differences are obtained for the summertime case with air mass convection. Domain-averaged liquid water paths and cloud condensate profiles are used to analyze the temporal and spatial variability of the simulated clouds. Finally, probability density functions of convection-related parameters are analyzed to investigate their dependance on model resolution and their impact on cloud formation and subsequent precipitation.
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Estaji, Mostafa, Erdem Coleri und Blaine Wruck. „Investigation of Tack Coat Bond Damage Mechanism in Asphalt Surfaced Pavements under Dynamic Truck Loads“. Transportation Research Record: Journal of the Transportation Research Board 2674, Nr. 3 (März 2020): 317–28. http://dx.doi.org/10.1177/0361198120909838.
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Bonding created by the tack coat allows the pavement system to carry heavy truck loads as a monolithic structure and improves the structural integrity. In Oregon and throughout the U.S.A., CSS-1H is the most commonly used tack coat type. However, field observations have revealed that new engineered tack coats, although more expensive, outperform the conventional types in relation to shear resistance. In this study, the impact of these new engineered emulsions on in-situ bond performance was quantified by laboratory testing and numerical modeling. Bonding damage performance of all tack coats was experimentally determined by using direct shear tests. Full-scale moving truck load models were developed and calibrated using the load-displacement parameters obtained from the laboratory shear tests. The impact of adverse construction conditions, such as dust, rain, and tack coat coverage, on tack coat bond damage under heavy truck loads was determined. It was concluded that the presence of dust had relatively the lowest contribution to shear damage. Rain during construction had the highest impact on the damage behavior and tack coat application on a wet surface increases the potential for damage by 20.1%. A 50% coverage of tack coat during construction resulted in 12.8% higher damage levels compared with 100% tack coat coverage of the surface area. Moving load models for heavy trucks caused 2.44 times more bonding damage at the bonded interface compared with the damage created by smaller trucks (F450).
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Barthlott, Christian, Amirmahdi Zarboo, Takumi Matsunobu und Christian Keil. „Importance of aerosols and shape of the cloud droplet size distribution for convective clouds and precipitation“. Atmospheric Chemistry and Physics 22, Nr. 3 (16.02.2022): 2153–72. http://dx.doi.org/10.5194/acp-22-2153-2022.
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Abstract. The predictability of deep moist convection is subject to large uncertainties resulting from inaccurate initial and boundary data, the incomplete description of physical processes, or microphysical uncertainties. In this study, we investigate the response of convective clouds and precipitation over central Europe to varying cloud condensation nuclei (CCN) concentrations and different shape parameters of the cloud droplet size distribution (CDSD), both of which are not well constrained by observations. We systematically evaluate the relative impact of these uncertainties in realistic convection-resolving simulations for multiple cases with different synoptic controls using the new icosahedral non-hydrostatic ICON model. The results show a large systematic increase in total cloud water content with increasing CCN concentrations and narrower CDSDs, together with a reduction in the total rain water content. This is related to a suppressed warm-rain formation due to a less efficient collision–coalescence process. It is shown that the evaporation at lower levels is responsible for diminishing these impacts on surface precipitation, which lies between +13 % and −16 % compared to a reference run with continental aerosol assumption. In general, the precipitation response was larger for weakly forced cases. We also find that the overall timing of convection is not sensitive to the microphysical uncertainties applied, indicating that different rain intensities are responsible for changing precipitation totals at the ground. Furthermore, weaker rain intensities in the developing phase of convective clouds can allow for a higher convective instability at later times, which can lead to a turning point with larger rain intensities later on. The existence of such a turning point and its location in time can have a major impact on precipitation totals. In general, we find that an increase in the shape parameter can produce almost as large a variation in precipitation as a CCN increase from maritime to polluted conditions. The narrowing of the CDSD not only decreases the absolute values of autoconversion and accretion but also decreases the relative role of the warm-rain formation in general, independent of the prevailing weather regime. We further find that increasing CCN concentrations reduce the effective radius of cloud droplets in a stronger manner than larger shape parameters. The cloud optical depth, however, reveals a similarly large increase with larger shape parameters when changing the aerosol load from maritime to polluted. By the frequency of updrafts as a function of height, we show a negative aerosol effect on updraft strength, leading to an enervation of deep convection. These findings demonstrate that both the CCN assumptions and the CDSD shape parameter are important for quantitative precipitation forecasting and should be carefully chosen if double-moment schemes are used for modeling aerosol–cloud interactions.
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Zhang, Yu, Yang Hong, Xuguang Wang, Jonathan J. Gourley, Xianwu Xue, Manabendra Saharia, Guangheng Ni et al. „Hydrometeorological Analysis and Remote Sensing of Extremes: Was the July 2012 Beijing Flood Event Detectable and Predictable by Global Satellite Observing and Global Weather Modeling Systems?“ Journal of Hydrometeorology 16, Nr. 1 (01.02.2015): 381–95. http://dx.doi.org/10.1175/jhm-d-14-0048.1.
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Abstract Prediction, and thus preparedness, in advance of flood events is crucial for proactively reducing their impacts. In the summer of 2012, Beijing, China, experienced extreme rainfall and flooding that caused 79 fatalities and economic losses of $1.6 billion. Using rain gauge networks as a benchmark, this study investigated the detectability and predictability of the 2012 Beijing event via the Global Hydrological Prediction System (GHPS), forced by the NASA Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis at near–real time and by the deterministic and ensemble precipitation forecast products from the NOAA Global Forecast System (GFS) at several lead times. The results indicate that the disastrous flooding event was detectable by the satellite-based global precipitation observing system and predictable by the GHPS forced by the GFS 4 days in advance. However, the GFS demonstrated inconsistencies from run to run, limiting the confidence in predicting the extreme event. The GFS ensemble precipitation forecast products from NOAA for streamflow forecasts provided additional information useful for estimating the probability of the extreme event. Given the global availability of satellite-based precipitation in near–real time and GFS precipitation forecast products at varying lead times, this study demonstrates the opportunities and challenges that exist for an integrated application of GHPS. This system is particularly useful for the vast ungauged regions of the globe.
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Kurowski, Marcin J., Kay Suselj, Wojciech W. Grabowski und Joao Teixeira. „Shallow-to-Deep Transition of Continental Moist Convection: Cold Pools, Surface Fluxes, and Mesoscale Organization“. Journal of the Atmospheric Sciences 75, Nr. 12 (08.11.2018): 4071–90. http://dx.doi.org/10.1175/jas-d-18-0031.1.
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Abstract Large-eddy simulation is used to investigate the effects of cold pools driven by rain evaporation on the shallow-to-deep convection transition over land. The physically consistent methodologies are developed to obtain a time-dependent reference ensemble without cold pools and to apply interactive surface heat fluxes without modeling of surface energy and water budgets. Three different simulation ensembles are contrasted. The reference ensemble, in the spirit of one-dimensional single-column models, eliminates cold pools by horizontally homogenizing negative buoyancy production due to rain evaporation. The additional ensembles complement the reference cold-pool-free ensemble by including cold pools and by applying either interactive or prescribed surface fluxes. Contrasting these ensembles suggests possible improvements of convection parameterization in large-scale models of weather and climate. Without cold pools, the reference ensemble preserves key features of buoyancy-driven cellular convection associated with a field of convective plumes, as assumed in a typical convection parameterization. With cold pools, a significant enhancement of surface heat and moisture fluxes and about an hour delay of their daily maximum is simulated. Cold pools enhance near-surface temperature and moisture standard deviations as well as maxima of the near-surface updraft velocity. They also lead to the reduction of cloud lateral entrainment, deeper vertical development of the cloud layer, and a few-times-larger accumulated surface precipitation. Interactive surface fluxes provide a damping mechanism that noticeably suppresses all these effects. Perhaps surprisingly, cold pools do not significantly change the cloud-base convective mass flux that approximately follows the evolution of surface heat fluxes.
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Wu, Shiang-Jen, Chih-Tsu Hsu und Che-Hao Chang. „Stochastic Modeling for Estimating Real-Time Inundation Depths at Roadside IoT Sensors Using the ANN-Derived Model“. Water 13, Nr. 21 (05.11.2021): 3128. http://dx.doi.org/10.3390/w13213128.
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This paper aims to develop a stochastic model (SM_EID_IOT) for estimating the inundation depths and associated 95% confidence intervals at the specific locations of the roadside water-level gauges, i.e., Internet of Things (IoT) sensors under the observed water levels/rainfalls and the precipitation forecasts given. The proposed SM_EID_IOT model is an ANN-derived one, a modified artificial neural network model (i.e., the ANN_GA-SA_MTF) in which the associated ANN weights are calibrated via a modified genetic algorithm with a variety of transfer functions considered. To enhance the reliability and accuracy of the proposed SM_EID_IOT model in the estimations of the inundation depths at the IoT sensors, a great number of the rainfall induced flood events as the training and validation datasets are simulated by the 2D hydraulic dynamic (SOBEK) model with the simulated rain fields via the stochastic generation model for the short-term gridded rainstorms. According to the results of model demonstration, Nankon catchment, located in northern Taiwan, the proposed SM_EID_IOT model can estimate the inundation depths at the various lead times with high reliability in capturing the validation datasets. Moreover, through the integrated real-time error correction method integrated with the proposed SM_EID_IOT model, the resulting corrected inundation-depth estimates exhibit a good agreement with the validated ones in time under an acceptable bias.
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Islam, Naima, Emmanuel K. Adanu, Alexander M. Hainen, Steve Burdette, Randy Smith und Steven Jones. „Evaluating the Impact of Freeway Service Patrol on Incident Clearance Times: A Spatial Transferability Test“. Journal of Advanced Transportation 2022 (18.07.2022): 1–10. http://dx.doi.org/10.1155/2022/5272747.
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Freeway service patrol (FSPs) programs have been considered as an effective tool for traffic incident management in minimizing the adverse effects of traffic incidents. In this study, random parameters hazard-based duration modeling method was used to evaluate the impact of the newly implemented Alabama Service and Assistance Patrol (ASAP) program, using incident clearance time as a performance measure. It was determined that there is a statistically significant difference in the factors that influence incidents clearance times between incidents that occurred inside and outside the ASAP regions. A total of five variables (on-road, nighttime, peak hours, rain, and fire response present) were observed to have random effects along with ten fixed effects variables on incidents occurring inside the ASAP regions. On the other hand, incidents that occurred outside the ASAP regions were found to have three random effects variables (on-road, nighttime, and fire response present) and seven fixed effects variables. The estimation results indicate a significant association of incident clearance times to incident related variables such as involvement of CMVs, fatality, vehicle towing, seat belt indicated as involved, and on-road incidents that occurred both inside and outside the ASAP regions. The results also reveal that incident clearance times are influenced strongly by temporal variables (e.g., nighttime), traffic factors (e.g., AADT), and operational variables (e.g., fire response present) for incidents both inside and outside the ASAP area models. Overall, it was observed that the incident clearance times recorded in the regions where the ASAP program is in effect are significantly different. The findings of this study are expected to be useful for the state traffic incident management (TIM) agencies in developing and executing strategies to minimize incident clearance times. Ultimately, the study provides a data-driven evidence-based assessment of the ASAP program in the state.
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Onderka, Milan, und Vladimír Chudoba. „The Wavelets show it – the transit time of water varies in time“. Journal of Hydrology and Hydromechanics 66, Nr. 3 (01.09.2018): 295–302. http://dx.doi.org/10.2478/johh-2018-0001.
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Abstract The ways how water from rain or melting snow flows over and beneath the Earth‘s surface affects the timing and intensity at which the same water leaves a catchment. Several mathematical techniques have been proposed to quantify the transit times of water by e.g. convolving the input-output tracer signals, or constructing frequency response functions. The primary assumption of these techniques is that the transit time is regarded time-invariant, i.e. it does not vary with temporarily changing e.g. soil saturation, evaporation, storage volume, climate or land use. This raises questions about how the variability of water transit time can be detected, visualized and analyzed. In this paper we present a case study to show that the transit time is a temporarily dynamic variable. Using a real-world example from the Lower Hafren catchment, Wales, UK, and applying the Continuous Wavelet Transform we show that the transit time distributions are time-variant and change with streamflow. We define the Instantaneous Transit Time Distributions as a basis for the Master Transit Time Distribution. We show that during periods of elevated runoff the transit times are exponentially distributed. A bell-shaped distribution of travel times was observed during times of lower runoff. This finding is consistent with previous investigations based on mechanistic and conceptual modeling in the study area according to which the diversity of water flow-paths during wet periods is attributable to contributing areas that shrink and expand depending on the duration of rainfall. The presented approach makes no assumptions about the shape of the transit time distribution. The mean travel time estimated from the Master Transit Time Distribution was ~54.3 weeks.
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Ulfah, Marfirah, Dyah Indriana Kusumastuti und Dwi Joko Winarno. „Analisis Metode Routing terhadap Hidrograf Banjir Sungai Way Sekampung di Way Kunyir Menggunakan HEC-HMS“. Jurnal Teknik Sipil 11, Nr. 2 (01.04.2020): 251–62. http://dx.doi.org/10.24002/jts.v11i2.3797.
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Flood events often occur in Indonesia so that quite a lot of people researched about the movement of floods and flood monitoring in the Watershed. The location of the study was carried out by the Way Sekampung river in Way Kunyir located in the Pringsewu district, Lampung province and is located downstream of the Batutegi dam. Flood tracing is intended to analyze the chances of a flood in the form of a flood hydrograph with or without using the Routing method and find out the results of some Routing methods in the watershed. The Routing method used in this study is Lag, Lag and K and Muskingum. The HEC-HMS modeling results state that peak discharge data when without Routing is greater than entering the Routing parameter. This is because entering the Routing parameter in modeling is very influential at peak times so that it affects the peak discharge at the watershed outlet. As a result of Muskingum Routing, the peak discharge is lower than before entering the flow routing, this is due to the occurrence of reservoirs along the river so that the peak discharge becomes lower than without Routing. The results of Lag Routing and Lag and K Routing are peak discharge decreased compared to before entering the Routing parameter. what should have happened to the peak discharge with Routing and without Routing remains the same, however, only peak discharge tranlations occur and there is travel time. This happens because there is no debit data at the station being reviewed so it uses rain data instead of HEC-HMS modeling.
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Ulfah, Marfirah, Dyah Indriana Kusumastuti und Dwi Joko Winarno. „Analisis Metode Routing terhadap Hidrograf Banjir Sungai Way Sekampung di Way Kunyir Menggunakan HEC-HMS“. Jurnal Teknik Sipil 15, Nr. 4 (05.11.2020): 251–62. http://dx.doi.org/10.24002/jts.v15i4.3799.
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Flood events often occur in Indonesia so that quite a lot of people researched about the movement of floods and flood monitoring in the Watershed. The location of the study was carried out by the Way Sekampung river in Way Kunyir located in the Pringsewu district, Lampung province and is located downstream of the Batutegi dam. Flood tracing is intended to analyze the chances of a flood in the form of a flood hydrograph with or without using the Routing method and find out the results of some Routing methods in the watershed. The Routing method used in this study is Lag, Lag and K and Muskingum. The HEC-HMS modeling results state that peak discharge data when without Routing is greater than entering the Routing parameter. This is because entering the Routing parameter in modeling is very influential at peak times so that it affects the peak discharge at the watershed outlet. As a result of Muskingum Routing, the peak discharge is lower than before entering the flow routing, this is due to the occurrence of reservoirs along the river so that the peak discharge becomes lower than without Routing. The results of Lag Routing and Lag and K Routing are peak discharge decreased compared to before entering the Routing parameter. what should have happened to the peak discharge with Routing and without Routing remains the same, however, only peak discharge tranlations occur and there is travel time. This happens because there is no debit data at the station being reviewed so it uses rain data instead of HEC-HMS modeling.
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SHARMA, KULDEEP, RAGHAVENDRA ASHRIT, R. BHATLA, R. RAKHI, G. R. IYENGAR und E. N. RAJAGOPAL. „Verification of heavy rainfall in NWP models : A case study“. MAUSAM 68, Nr. 4 (02.12.2021): 699–712. http://dx.doi.org/10.54302/mausam.v68i4.772.
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Forecasting of heavy rainfall events is still a challenge even for the most advanced state-of-art high resolution NWP modelling systems. Very often the models fail to accurately predict the track and movement of the low pressure systems leading to large spatial errors in the predicted rain. Quantification of errors in forecast rainfall location and amounts is important for forecasters (to choose a forecast and interpret) and modelers for monitoring the impact of changes and improvements in model physics and dynamics configurations. This study aims to quantify and summarize errors in rainfall forecast for heavy rains associated with a Bay of Bengal (BOB) low pressure systems. The verification analysis is based on three heavy rain events during June to September (JJAS) 2015. The performance of the three deterministic models, NCMRWF’s Global Forecast Systems (NGFS), NCMRWF’s Unified Model (NCUM) and Australian Community Climate and Earth-System Simulator – Global (ACCESS-G) in predicting these heavy rainfall events has been analysed. In addition to standard verification metrics like RMSE, ETS, POD and HK Score, this paper also uses new family of scores like EDS (Extreme Dependency Score), EDI (Extremal Dependence Index) and Symmetric EDI with special emphasis on verification of extreme rainfall to bring out the relative performance of the models for these three rainfall events. The results indicate that Unified modeling framework in NCUM and ACCESS-G by and large performs better than NGFS in rainfall forecasts over India specially at higher lead times. Relatively improved skill in NCUM forecasts can be attributed to (i) improved resolution (~17 km) and (ii) END Game dynamics of NCUM.
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Cheng, Irene, Abdulla Al Mamun und Leiming Zhang. „A synthesis review on atmospheric wet deposition of particulate elements: scavenging ratios, solubility, and flux measurements“. Environmental Reviews 29, Nr. 3 (September 2021): 340–53. http://dx.doi.org/10.1139/er-2020-0118.
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Atmospheric dry and wet deposition of particulate matter controls its lifetime in air and contributes to the environmental burden of toxic pollutants and thus has important implications on human and ecosystem health. This synthesis review focuses on atmospheric wet deposition of particulate elements and analyzed their scavenging ratios (i.e., ratio of concentration in precipitation to that in ambient air), solubility, and wet deposition flux measurements based on published studies in the literature, aiming to gather updated knowledge that can be used for modeling their wet deposition. Our analysis finds that scavenging ratios of a specific element have a narrow range. Overall, elemental scavenging ratios for snow are approximately three times higher than those for rain. Elements that are bound to coarse (PM2.5–10) particles have larger scavenging ratios than those bound to fine (PM2.5) particles, except for Fe and Si. Solubility of elements in rainwater ranges from 8% (Fe) to 94% (Ca). Solubility is moderately correlated with scavenging ratio, possibly explaining the lower scavenging ratios of Fe and Si compared with other elements with similar fine fractions. Data collected from North America, Europe, the Middle East, and Asia show that the wet fluxes of Al and Fe are orders of magnitude greater than those of routinely monitored anthropogenic elements (Zn, Pb, Cu, Ni, Cd, Cr). Wet deposition fluxes of particulate elements in the Middle East exceed those in other regions, likely due to regional transport of dust and soil resuspension. Fluxes from all regions are a factor of two to three times greater in industrialized and urban locations than in rural and remote locations because of industrial, vehicular, and soil and mineral dust emissions. Dry deposition fluxes are usually greater than wet deposition fluxes, although to varying degrees according to co-located measurements. Based on the relationships between scavenging ratio and the elemental PM2.5 fraction under rain and snow conditions, we derived regression equations for estimating scavenging ratios of particulate elements for which measurements are limited. Such knowledge and data improve the quantification of atmospheric deposition fluxes for an expanded list of metals and metalloids and the understanding of pathways contributing to ecological risk.
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Lohmann, U., und S. Ferrachat. „Impact of parametric uncertainties on the present-day climate and on the anthropogenic aerosol effect“. Atmospheric Chemistry and Physics Discussions 10, Nr. 8 (13.08.2010): 19195–217. http://dx.doi.org/10.5194/acpd-10-19195-2010.
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Abstract. Clouds constitute a large uncertainty in global climate modeling and climate change projections as many clouds are smaller than the size of a model grid box. Some processes, such as the rates of rain and snow formation that have a large impact on climate, cannot be observed. These processes are thus used as tuning parameters in order to achieve radiation balance. Here we systematically investigate the impact of various tunable parameters within the convective and stratiform cloud schemes and of the ice cloud optical properties on the present-day climate in terms of clouds, radiation and precipitation. The total anthropogenic aerosol effect between pre-industrial and present-day times amounts to −1.00 W m−2 obtained as an average over all simulations as compared to −1.02 W m−2 from those simulations where the global annual mean top-of-the atmosphere radiation balance is within ±1 W m−2. The parametric uncertainty when taking all simulations into account has an uncertainty range of 25% between the minimum and maximum value. It is reduced to 11% when only the simulations with a balanced top-of-the atmosphere radiation are considered.
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Kumar, Pappu, Madhusudan Narayan und Mani Bhushan. „Rainfall Intensity Duration Frequency Curve Statistical Analysis and Modeling for Patna, Bihar“. BOHR International Journal of Civil Engineering and Environmental Science 2, Nr. 1 (2023): 65–73. http://dx.doi.org/10.54646/bicees.008.
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Using data from 41 years in Patna, India, the study’s goal is to analyze the trends of how often it rains on a weekly, seasonal, and annual basis (1981–2020). First, utilizing the intensity-duration-frequency (IDF) curve and the relationship by statistically analyzing rainfall, the historical rainfall data set for Patna, India, during a 41-year period (1981–2020), was evaluated for its quality. Changes in the hydrologic cycle as a result of increased greenhouse gas emissions are expected to induce variations in the intensity, length, and frequency of precipitation events. One strategy to lessen vulnerability is to quantify probable changes and adapt to them. Techniques such as log-normal, normal, and Gumbel are used (EV-I). Distributions were created with durations of 1, 2, 3, 6, and 24 hours and return times of 2, 5, 10, 25, and 100 years. There were also mathematical correlations discovered between rainfall and recurrence interval. Findings: Based on findings, the Gumbel approach produced the highest intensity values, whereas the other approaches produced values that were close to each other. The data indicates that 461.9 mm of rain fell during the monsoon season’s 301st week. However, it was found that the 29th week had the greatest average rainfall, 92.6 mm. With 952.6 mm on average, the monsoon season saw the highest rainfall. Calculations revealed that the yearly rainfall averaged 1171.1 mm. Using Weibull’s method, the study was subsequently expanded to examine rainfall distribution at different recurrence intervals of 2, 5, 10, and 25 years. Rainfall and recurrence interval mathematical correlations were also developed. Further regression analysis revealed that short wave irrigation, wind direction, wind speed, pressure, relative humidity, and temperature all had a substantial influence on rainfall. Originality and Value: The results of the rainfall IDF curves can provide useful information to policymakers in making appropriate decisions in managing and minimizing floods in the study area.
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Kumar, Pappu, Madhusudan Narayan und Mani Bhushan. „Rainfall Intensity Duration Frequency Curve Statistical Analysis and Modeling for Patna, Bihar“. BOHR International Journal of Civil Engineering and Environmental Science 2, Nr. 1 (2023): 65–73. http://dx.doi.org/10.54646/bijcees.008.
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Using data from 41 years in Patna, India, the study’s goal is to analyze the trends of how often it rains on a weekly, seasonal, and annual basis (1981–2020). First, utilizing the intensity-duration-frequency (IDF) curve and the relationship by statistically analyzing rainfall, the historical rainfall data set for Patna, India, during a 41-year period (1981–2020), was evaluated for its quality. Changes in the hydrologic cycle as a result of increased greenhouse gas emissions are expected to induce variations in the intensity, length, and frequency of precipitation events. One strategy to lessen vulnerability is to quantify probable changes and adapt to them. Techniques such as log-normal, normal, and Gumbel are used (EV-I). Distributions were created with durations of 1, 2, 3, 6, and 24 hours and return times of 2, 5, 10, 25, and 100 years. There were also mathematical correlations discovered between rainfall and recurrence interval. Findings: Based on findings, the Gumbel approach produced the highest intensity values, whereas the other approaches produced values that were close to each other. The data indicates that 461.9 mm of rain fell during the monsoon season’s 301st week. However, it was found that the 29th week had the greatest average rainfall, 92.6 mm. With 952.6 mm on average, the monsoon season saw the highest rainfall. Calculations revealed that the yearly rainfall averaged 1171.1 mm. Using Weibull’s method, the study was subsequently expanded to examine rainfall distribution at different recurrence intervals of 2, 5, 10, and 25 years. Rainfall and recurrence interval mathematical correlations were also developed. Further regression analysis revealed that short wave irrigation, wind direction, wind speed, pressure, relative humidity, and temperature all had a substantial influence on rainfall. Originality and Value: The results of the rainfall IDF curves can provide useful information to policymakers in making appropriate decisions in managing and minimizing floods in the study area.
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Song, Ling, Julia Drewer, Bo Zhu, Minghua Zhou, Nicholas Cowan, Peter Levy und Ute Skiba. „The impact of atmospheric N deposition and N fertilizer type on soil nitric oxide and nitrous oxide fluxes from agricultural and forest Eutric Regosols“. Biology and Fertility of Soils 56, Nr. 7 (22.06.2020): 1077–90. http://dx.doi.org/10.1007/s00374-020-01485-6.
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Abstract Agricultural and forest soils with low organic C content and high alkalinity were studied over 17 days to investigate the potential response of the atmospheric pollutant nitric oxide (NO) and the greenhouse gas nitrous oxide (N2O) on (1) increased N deposition rates to forest soil; (2) different fertilizer types to agricultural soil and (3) a simulated rain event to forest and agricultural soils. Cumulative forest soil NO emissions (148–350 ng NO-N g−1) were ~ 4 times larger than N2O emissions (37–69 ng N2O-N g−1). Contrary, agricultural soil NO emissions (21–376 ng NO-N g−1) were ~ 16 times smaller than N2O emissions (45–8491 ng N2O-N g−1). Increasing N deposition rates 10 fold to 30 kg N ha−1 yr−1, doubled soil NO emissions and NO3− concentrations. As such high N deposition rates are not atypical in China, more attention should be paid on forest soil NO research. Comparing the fertilizers urea, ammonium nitrate, and urea coated with the urease inhibitor ‘Agrotain®,’ demonstrated that the inhibitor significantly reduced NO and N2O emissions. This is an unintended, not well-known benefit, because the primary function of Agrotain® is to reduce emissions of the atmospheric pollutant ammonia. Simulating a climate change event, a large rainfall after drought, increased soil NO and N2O emissions from both agricultural and forest soils. Such pulses of emissions can contribute significantly to annual NO and N2O emissions, but currently do not receive adequate attention amongst the measurement and modeling communities.
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Philipp, Andy, Florian Kerl, Uwe Büttner, Christine Metzkes, Thomas Singer, Michael Wagner und Niels Schütze. „Small-scale (flash) flood early warning in the light of operational requirements: opportunities and limits with regard to user demands, driving data, and hydrologic modeling techniques“. Proceedings of the International Association of Hydrological Sciences 373 (12.05.2016): 201–8. http://dx.doi.org/10.5194/piahs-373-201-2016.
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Abstract. In recent years, the Free State of Saxony (Eastern Germany) was repeatedly hit by both extensive riverine flooding, as well as flash flood events, emerging foremost from convective heavy rainfall. Especially after a couple of small-scale, yet disastrous events in 2010, preconditions, drivers, and methods for deriving flash flood related early warning products are investigated. This is to clarify the feasibility and the limits of envisaged early warning procedures for small catchments, hit by flashy heavy rain events. Early warning about potentially flash flood prone situations (i.e., with a suitable lead time with regard to required reaction-time needs of the stakeholders involved in flood risk management) needs to take into account not only hydrological, but also meteorological, as well as communication issues. Therefore, we propose a threefold methodology to identify potential benefits and limitations in a real-world warning/reaction context. First, the user demands (with respect to desired/required warning products, preparation times, etc.) are investigated. Second, focusing on small catchments of some hundred square kilometers, two quantitative precipitation forecasts are verified. Third, considering the user needs, as well as the input parameter uncertainty (i.e., foremost emerging from an uncertain QPF), a feasible, yet robust hydrological modeling approach is proposed on the basis of pilot studies, employing deterministic, data-driven, and simple scoring methods.
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SAHRAOUI, Meriem, Samia CHERGUI, Ali BELMEZITI und Rachid ZEGAIT. „Ingenious Rainwater Harvesting System within the Algiers Ottoman Residential Buildings (Reconstitution and Performance Assessment)“. International Journal of Conservation Science 14, Nr. 2 (15.06.2023): 399–416. http://dx.doi.org/10.36868/ijcs.2023.02.02.
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This article deals more particularly with the architectural reconstitution and the hydraulic checking of the rainwater harvesting system (RWH-system) installation in some residential buildings in Ottoman Algiers (16th to 18th centuries), where this water was intended for various domestic uses. This work was applied to two cases (Khdawedj-El'Amia and HassanPasha palaces). An architectural reconstitution by three-dimensional modeling was made based on investigations and bibliographic research on the system. In contrast, hydraulic verification was made according to the current European sizing standards based on rainfall records for over 100 years. The results indicate that these buildings are equipped with an innovative and efficient hydraulic system based on relativity between rain, roof, and stored volume (djeb), according to current standards; this system has the potential to meet the needs of the populations and ensure their water autonomy, particularly in times of water scarcity. And consequently, rainwater management in a secure way. On the other hand, the results assess the possibility of returning the RWH system to function today. It provides helpful information to develop an action plan and intervention strategies for restoring the (RWHsystem) in the heritage residential buildings for improving sustainability and maintaining the built heritage values of the historic Ottoman Algiers.
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Carisse, Odile, und Vincent Morissette-Thomas. „Epidemiology of Grape Anthracnose: Factors Associated with Defoliation of Grape Leaves Infected by Elsinoë ampelina“. Plant Disease 97, Nr. 2 (Februar 2013): 222–30. http://dx.doi.org/10.1094/pdis-04-12-0393-re.
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Anthracnose is a serious disease that affects several grape cultivars. Infected leaves drop prematurely, and severe epidemics result in poor or no yield. Because the factors associated with grape defoliation in vineyards with a history of anthracnose were not well known, this study was undertaken to investigate the relationship between weather-, disease-, and host-related factors and survival of leaves. From 2006 to 2008, weather, anthracnose severity, and leaf emergence were monitored in an unsprayed experimental vineyard naturally infested with Elsinoë ampelina. Each year, two to three times weekly, the number of leaves and the proportion of leaf area diseased (PLAD) were monitored on 10 vines and 2 shoots per vine, for a total of 785 leaves. Survival analysis was used to investigate the factors influencing defoliation and to model time-to-death of grape leaves. Estimated median survival time was 117 to 121 days. Based on Kaplan-Meier estimates of survival probabilities, season type, PLAD per leaf and PLAD per shoot at first assessment, duration and amount of rain at first infection, severity of infection and leaf age at first infection and at first severe infection significantly influenced leaf survival. Based on accelerated time failure modeling, using the Weibull distribution, the most significant variables were PLAD per leaf and PLAD per shoot at first assessment, leaf age at first infection, and duration of rain. Each additional percent increase in PLAD per leaf, in PLAD per shoot, or in rainy days accelerated the time-to-death of grape leaves by 2.84, 1.02, and 0.66%, respectively, whereas for each additional day of leaf age at time of first infection, there was a 2.88% deceleration of the time to death. Results suggested that to avoid premature leaf drop, disease severity should be maintained below 25% leaf area diseased, which can be achieved by sanitation measures designed to reduce inoculum levels and by applying fungicide early in the season to prevent infection of young leaves.
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Amengual, A., R. Romero, M. Gómez, A. Martín und S. Alonso. „A Hydrometeorological Modeling Study of a Flash-Flood Event over Catalonia, Spain“. Journal of Hydrometeorology 8, Nr. 3 (01.06.2007): 282–303. http://dx.doi.org/10.1175/jhm577.1.
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Abstract During the early morning of 10 June 2000, the Catalonia region was affected by a hazardous convective rainfall episode that produced a large increase on flow regimes in many internal catchments of the region. The present modeling study is focused upon the Llobregat basin, the biggest internal catchment with a drainage area of 5040 km2. The first objective of the study is the characterization of the watershed hydrological response to this flash-flood event based on rain gauge data and the Hydrologic Engineering Center’s Hydrological Modeling System (HEC-HMS) runoff model. The HEC-HMS model has been calibrated using five episodes of similar torrential characteristics, and the effects of the spatial segmentation of the basin and of the temporal scale of the input rainfall field have been examined. These kinds of episodes present short recurrence intervals in Mediterranean Spain, and the use of mesoscale forecast driven runoff simulation systems for increasing the lead times of the emergency management procedures is a valuable issue to explore. The second objective uses NCEP and ECMWF analyses to initialize the nonhydrostatic fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) in order to simulate the 10 June 2000 flash-flood episode with appropriate space and time scales to force the runoff model. The final objective analyzes the sensitivity of the catchment’s response to the spatial and temporal uncertainty of the rainfall pattern based on an ensemble of perturbed MM5 simulations. MM5 perturbations are introduced through small shifts and changes in intensity of the precursor upper-level synoptic-scale trough. Main results indicate that 1) an optimum configuration of the runoff model can be clearly defined that best adjusts the simulated basin’s hydrological response to observed peak discharges, their timing, and total volume; 2) the MM5-control driven runoff simulation shows a reasonable reproduction of the observed discharge at the basin’s outlet and appears to be a suitable tool for the hydrometeorological forecasting of flash floods in the Llobregat basin as a whole; and 3) the ensemble of perturbed runoff simulations does not exhibit any relevant degradation of the forecast skill, and some of the members even outperform the control experiment at different stream gauge locations. That is, the catchment is relatively insensitive to rainfall forecast errors of a few tenths of kilometers and no more than 1–2 h.
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Lohmann, U., und S. Ferrachat. „Impact of parametric uncertainties on the present-day climate and on the anthropogenic aerosol effect“. Atmospheric Chemistry and Physics 10, Nr. 23 (01.12.2010): 11373–83. http://dx.doi.org/10.5194/acp-10-11373-2010.
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Abstract. Clouds constitute a large uncertainty in global climate modeling and climate change projections as many clouds are smaller than the size of a model grid box. Some processes, such as the rates of rain and snow formation that have a large impact on climate, cannot be observed. The uncertain parameters in the representation of these processes are therefore adjusted in order to achieve radiation balance. Here we systematically investigate the impact of key tunable parameters within the convective and stratiform cloud schemes and of the ice cloud optical properties on the present-day climate in terms of clouds, radiation and precipitation. The total anthropogenic aerosol effect between pre-industrial and present-day times amounts to −1.00 W m−2 obtained as an average over all simulations as compared to −1.02 W m−2 from those simulations where the global annual mean top-of-the atmosphere radiation balance is within ±1 W m−2. Thus tuning of the present-day climate does not seem to have an influence on the total anthropogenic aerosol effect. The parametric uncertainty regarding the above mentioned cloud parameters has an uncertainty range of 25% between the minimum and maximum value when taking all simulations into account. It is reduced to 11% when only the simulations with a balanced top-of-the atmosphere radiation are considered.
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Chernogor, L. F., A. N. Nekos, G. V. Titenko und L. L. Chornohor. „The influence of the El Niño phenomenon on appearance of large-scale forest fires and their ecological consequences“. Visnyk of V. N. Karazin Kharkiv National University series "Ecology", Nr. 30 (24.07.2024): 76–90. https://doi.org/10.26565/1992-4259-2024-30-06.
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The frequency and intensity of forest fires is increasing year by year. It is due to global warming, which is associated with both natural and anthropogenic phenomena and processes There is another mechanism of global impact on the weather, abnormally high summer temperatures, severity and frequency of droughts, intensity and frequency of forest fires and their consequences. It is associated with the unique, cyclical, natural phenomenon of El Niño. The possibility of this phenomenon influence on the intensity of large-scale forest fires and their ecological consequences cannot be excluded, in accordance with the analysis of these processes and their quantitative assessment. There is reason to believe that the phenomenon may affect the intensity and frequency of forest fires in countries nearby. Such a country is, in particular, Chile, which experiences intense forest fires every year. Their intensity is compared to the intensity of record fires in Ukraine in 2020. Purpose. Comparative assessment of the ecological consequences of large-scale forest fires stimulated by natural and anthropogenic impacts (using the example of Ukraine and Chile in 2014–2024). Methods. Analytical review of the research problem, systems analysis of a number of accompanying processes, mathematical modeling and theoretical calculations. A methodology has been developed for assessing the ecological consequences of fires and burning of buildings in populated areas. Results. Areas of fires in 2017 and 2023 reached 0,5 million ha in Chile. Smoke ejections approached 10 Mt, which was one hundred thousand times higher than the norm. There were about 0,5 Gt of carbon dioxide ejections. They exceeded the background value in the fire areas by 200 times. The ejection of soot, carbon monoxide and hydrocarbons exceeded the norm by 120 thousand, 4 thousand and 160 times, respectively. Ejections of PM 2.5 microparticles and polyaromatic hydrocarbons exceeded the norm by 40 million and more than a million times, respectively. Ejections of nitrogen and sulfur oxides exceeded the norm by 3 thousand and 400–800 times, respectively. The combustion energy exceeded 2 thousand PJ, and the average combustion power exceeded 1 TW. The acoustic radiation energy, reaching 7 PJ, exceeded the background value by more than 1000 times. At the same time, the power of this radiation exceeded the norm by more than one hundred thousand times and was about 700 GW. Nitrogen ejections were the largest, reaching 1–10 Mt. The ejection of potassium, calcium, iron, zinc, chromium, and bromine was significant. The ejections of other chemical elements were significantly less. The construction of mathematical models made it possible to calculate the concentration and mass of harmful substances emitted during the burning of populated areas caused by forest fires. For the first time, it was established that ejections of substances during this can be significant. For the first time, the need to take into account the influence of micron smoke particles and polyaromatic hydrocarbons, which lead, respectively, to diseases of the respiratory tract, cardiovascular system and oncological diseases of residents of the entire country and beyond, was substantiated, and their mass and concentration have been calculated. Ejections of nitrogen and sulfur oxides, which stimulate the occurrence of acid rain, have been assessed. A comparative analysis of the characteristics and consequences of forest fires showed that they were more large-scale in Chile in 2017 and 2023 (almost 20 times) and in February 2024 than the record fires in Ukraine in 2020 in terms of their parameters and consequences. Conclusions. Mathematical modeling and calculations showed that the ecological consequences of large forests and buildings burning in Chile in 2023–2024 were catastrophic. They were accompanied by an intensification of the El Niño phenomenon. No less widespread were the ecological consequences of large-scale forest fires in Chile in 2017, caused by the hottest summer at that time. The size scale of fires in Chile and their consequences were many times higher than the corresponding parameters for the record fires in Ukraine in 2020.
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DeGraaf, Richard M., und Mariko Yamasaki. „Effects of Edge Contrast on Redback Salamander Distribution in Even-Aged Northern Hardwoods“. Forest Science 48, Nr. 2 (01.05.2002): 351–63. http://dx.doi.org/10.1093/forestscience/48.2.351.
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Abstract Terrestrial salamanders are sensitive to forest disturbance associated with even-aged management. We studied the distribution of redback salamanders (Plethodon cinereus) for 4 yr at edges between even-aged northern hardwood stands along three replicate transects in each of three edge contrast types: regeneration/mature, sapling/mature, and poletimber/mature in northern New Hampshire. We used 2 m2 coverboard clusters at the edge, and at 5, 10, 20, and 40 m into the younger and mature stands. Salamanders were surveyed 12 times per year from May to October, approximately once every 2 wk, usually within 24 hr of a rain event. Habitat variables included board station soil temperature, litter depth, organic layer depth, depth to soil mottling, herbaceous cover, down log cover, three classes of understory hardwood stem density [0.5–1m tall, 1–2 m tall and <10 cm dbh, and >2 m tall], softwood stem density, Rubus/other stem density, and overstory basal area (ba) and mean dbh. A total of 4,038 redback salamanders were detected during 432 transect counts. The mean salamander density was 0.41/m2 across regenerating stand transects, 0.47m2 across sapling transects, and 0.69 m2 across poletimber transects. We analyzed salamander distribution by edge type, replicate, year, station (distance from edge), and their interactions. There were significant differences in salamander detections among edge types, replicates, station, and years for both counts across entire younger forest/mature forest transects and across the younger forest transect sections. There were significant interactions between edge type and distance from edge. Salamander detections were greater (P < 0.001) in pole/mature edges than in sapling/mature and regeneration/mature edges in all years. Counts in sapling and regeneration stands were not different. The pattern of salamander abundance was similar across all edge types: low abundance 40 m out in the younger stand, increased abundance near or at the edge, a decrease just inside the edge, peak abundance in the mature stand (20 m inside the edge), and decline at 40 m in the mature stand. Salamander counts differed among years across all transects, tracking yearly precipitation differences. Counts also varied seasonally; early spring and late summer counts were higher (P < 0.001) than counts in early to mid-summer and fall. Salamander counts were negatively related to total understory stem density, density of hardwood stems >2 cm tall and <10 cm dbh, and percent herb cover, and positively related to soil organic layer depth (P values <0.10). A stepwise regression model included percent herbaceous ground cover, number of hardwood stems >2 m tall and <10 cm dbh, and organic soil layer depth, and explained 29% of the variation in redback salamander counts. Our findings are consistent with reported recovery times for redback salamanders after clearcut harvesting; recovery rates even along edges may take about 30 yr. Seasonal and yearly variation must be taken into account if terrestrial salamanders are used in monitoring programs. FOR. SCI. 48(2):351–363.
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Dale, A. W., S. Sommer, U. Lomnitz, I. Montes, T. Treude, J. Gier, C. Hensen et al. „Organic carbon production, mineralization and preservation on the Peruvian margin“. Biogeosciences Discussions 11, Nr. 9 (09.09.2014): 13067–126. http://dx.doi.org/10.5194/bgd-11-13067-2014.
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Abstract. Carbon cycling in Peruvian margin sediments (11° S and 12° S) was examined at 16 stations from 74 m on the inner shelf down to 1024 m water depth by means of in situ flux measurements, sedimentary geochemistry and modeling. Bottom water oxygen was below detection limit down to ca. 400 m and increased to 53 μM at the deepest station. Sediment accumulation rates and benthic dissolved inorganic carbon fluxes decreased rapidly with water depth. Particulate organic carbon (POC) content was lowest on the inner shelf and at the deep oxygenated stations (< 5%) and highest between 200 and 400 m in the oxygen minimum zone (OMZ, 15–20%). The organic carbon burial efficiency (CBE) was unexpectedly low on the inner shelf (< 20%) when compared to a global database, for reasons which may be linked to the frequent ventilation of the shelf by oceanographic anomalies. CBE at the deeper oxygenated sites was much higher than expected (max. 81%). Elsewhere, CBEs were mostly above the range expected for sediments underlying normal oxic bottom waters, with an average of 51 and 58% for the 11° S and 12° S transects, respectively. Organic carbon rain rates calculated from the benthic fluxes alluded to a very efficient mineralization of organic matter in the water column, with a Martin curve exponent typical of normal oxic waters (0.88 ± 0.09). Yet, mean POC burial rates were 2–5 times higher than the global average for continental margins. The observations at the Peruvian margin suggest that a lack of oxygen does not affect the degradation of organic matter in the water column but promotes the preservation of organic matter in marine sediments.
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Capra, Lucia, Velio Coviello, Lorenzo Borselli, Víctor-Hugo Márquez-Ramírez und Raul Arámbula-Mendoza. „Hydrological control of large hurricane-induced lahars: evidence from rainfall-runoff modeling, seismic and video monitoring“. Natural Hazards and Earth System Sciences 18, Nr. 3 (09.03.2018): 781–94. http://dx.doi.org/10.5194/nhess-18-781-2018.
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Abstract. The Volcán de Colima, one of the most active volcanoes in Mexico, is commonly affected by tropical rains related to hurricanes that form over the Pacific Ocean. In 2011, 2013 and 2015 hurricanes Jova, Manuel and Patricia, respectively, triggered tropical storms that deposited up to 400 mm of rain in 36 h, with maximum intensities of 50 mm h −1. The effects were devastating, with the formation of multiple lahars along La Lumbre and Montegrande ravines, which are the most active channels in sediment delivery on the south-southwest flank of the volcano. Deep erosion along the river channels and several marginal landslides were observed, and the arrival of block-rich flow fronts resulted in damages to bridges and paved roads in the distal reaches of the ravines. The temporal sequence of these flow events is reconstructed and analyzed using monitoring data (including video images, seismic records and rainfall data) with respect to the rainfall characteristics and the hydrologic response of the watersheds based on rainfall-runoff numerical simulation. For the studied events, lahars occurred 5–6 h after the onset of rainfall, lasted several hours and were characterized by several pulses with block-rich fronts and a maximum flow discharge of 900 m3 s −1. Rainfall-runoff simulations were performer using the SCS-curve number and the Green–Ampt infiltration models, providing a similar result in the detection of simulated maximum watershed peaks discharge. Results show different behavior for the arrival times of the first lahar pulses that correlate with the simulated catchment's peak discharge for La Lumbre ravine and with the peaks in rainfall intensity for Montegrande ravine. This different behavior is related to the area and shape of the two watersheds. Nevertheless, in all analyzed cases, the largest lahar pulse always corresponds with the last one and correlates with the simulated maximum peak discharge of these catchments. Data presented here show that flow pulses within a lahar are not randomly distributed in time, and they can be correlated with rainfall peak intensity and/or watershed discharge, depending on the watershed area and shape. This outcome has important implications for hazard assessment during extreme hydro-meteorological events, as it could help in providing real-time alerts. A theoretical rainfall distribution curve was designed for Volcán de Colima based on the rainfall and time distribution of hurricanes Manuel and Patricia. This can be used to run simulations using weather forecasts prior to the actual event, in order to estimate the arrival time of main lahar pulses, usually characterized by block-rich fronts, which are responsible for most of the damage to infrastructure and loss of goods and lives.
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Peter, Madlen, Henning W. Rust und Uwe Ulbrich. „Interannual variations in the seasonal cycle of extreme precipitation in Germany and the response to climate change“. Natural Hazards and Earth System Sciences 24, Nr. 4 (10.04.2024): 1261–85. http://dx.doi.org/10.5194/nhess-24-1261-2024.
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Abstract. Annual maxima of daily precipitation sums can be typically described well with a stationary generalized extreme value (GEV) distribution. In many regions of the world, such a description does also work well for monthly maxima for a given month of the year. However, the description of seasonal and interannual variations requires the use of non-stationary models. Therefore, in this paper we propose a non-stationary modeling strategy applied to long time series from rain gauges in Germany. Seasonal variations in the GEV parameters are modeled with a series of harmonic functions and interannual variations with higher-order orthogonal polynomials. By including interactions between the terms, we allow for the seasonal cycle to change with time. Frequently, the shape parameter ξ of the GEV is estimated as a constant value also in otherwise instationary models. Here, we allow for seasonal–interannual variations and find that this is beneficial. A suitable model for each time series is selected with a stepwise forward regression method using the Bayesian information criterion (BIC). A cross-validated verification with the quantile skill score (QSS) and its decomposition reveals a performance gain of seasonally–interannually varying return levels with respect to a model allowing for seasonal variations only. Some evidence can be found that the impact of climate change on extreme precipitation in Germany can be detected, whereas changes are regionally very different. In general, an increase in return levels is more prevalent than a decrease. The median of the extreme precipitation distribution (2-year return level) generally increases during spring and autumn and is shifted to later times in the year; heavy precipitation (100-year return level) rises mainly in summer and occurs earlier in the year.
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Plake, D., M. Sörgel, P. Stella, A. Held und I. Trebs. „Influence of meteorology and anthropogenic pollution on chemical flux divergence of the NO-NO<sub>2</sub>-O<sub>3</sub> triad above and within a natural grassland canopy“. Biogeosciences Discussions 11, Nr. 7 (14.07.2014): 10737–77. http://dx.doi.org/10.5194/bgd-11-10737-2014.
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Abstract. The detailed understanding of surface–atmosphere exchange of reactive trace gas species is a crucial precondition for reliable modeling of processes in atmospheric chemistry. Plant canopies significantly impact the atmospheric budget of trace gases. In the past, many studies focused on taller forest canopies or crops, where the bulk plant material is concentrated in the uppermost canopy layer. However, within grasslands, a land-cover class that globally covers vast terrestrial areas, the canopy structure is fundamentally different, as the main biomass is concentrated in the lowest canopy part. This has obvious implications for aerodynamic in-canopy transport, and consequently also impacts on global budgets of key species in atmospheric chemistry such as nitric oxide (NO), nitrogen dioxide (NO2) and ozone (O3). This study presents for the first time a~comprehensive data set of directly measured in-canopy transport times and aerodynamic resistances, chemical timescales, Damköhler numbers, trace gas and micrometeorological measurements for a natural grassland canopy (canopy height = 0.6 m). Special attention is paid to the impact of contrasting meteorological and air chemical conditions on in-canopy transport and chemical flux divergence. Our results show that the grassland canopy is decoupled throughout the day. In the lower canopy, the measured transport times are fastest during nighttime, which is due to convection during nighttime and stable stratification during daytime in this layer. The inverse was found in the layers above. During periods of low wind speed and high NOx (NO+NO2) levels, the effect of canopy decoupling on trace gas transport was found especially distinct. The aerodynamic resistance in the lower canopy (0.04–0.2 m) was around 1000 s m−1, thus as high as values from literature representing the lowest meter of an Amazonian rain forest canopy. The aerodynamic resistance representing the bulk canopy was found to be more than 3–4 times higher as in forests. Calculated Damköhler numbers (ratio of transport and chemical timescales) suggested a strong flux divergence for the NO-NO2-O3 triad within the canopy during daytime. At that time, the timescale of NO2 plant uptake ranged from 90 to 160 s and was the fastest relevant timescale, i.e. faster than the reaction of NO and O3. Thus, our results clearly reveal that grassland canopies of similar structure have a strong potential to retain soil emitted NO by uptake of NO2 by the plants. Furthermore, a photo-chemical O3 production above the canopy was observed, which resulted from a~surplus of NO2 from the NO-NO2-O3 photostationary state. The O3 production was one order of magnitude higher during high NOx than during low NOx periods and resulted in an O3 flux underestimation, which was observed for the first time.
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Amengual, A., R. Romero, M. Vich und S. Alonso. „Inclusion of potential vorticity uncertainties into a hydrometeorological forecasting chain: application to a medium size basin of Mediterranean Spain“. Hydrology and Earth System Sciences Discussions 6, Nr. 1 (28.01.2009): 535–87. http://dx.doi.org/10.5194/hessd-6-535-2009.
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Abstract. The improvement of the short- and mid-range numerical runoff forecasts over the flood-prone Spanish Mediterranean area is a challenging issue. This work analyses four intense precipitation events which produced floods of different magnitude over the Llobregat river basin, a medium size catchment located in Catalonia, north-eastern Spain. One of them was a devasting flash flood – known as the "Montserrat" event – which produced 5 fatalities and material losses estimated at about 65 million euros. The characterization of the Llobregat basin's hydrological response to these floods is first assessed by using rain-gauge data and the Hydrologic Engineering Center's Hydrological Modeling System (HEC-HMS) runoff model. In second place, the non-hydrostatic fifth-generation Pennsylvania State University/NCAR mesoscale model (MM5) is nested within the ECMWF large-scale forecast fields in a set of 54 h period simulations to provide quantitative precipitation forecasts (QPFs) for each hydrometeorological episode. The hydrological model is forced with these QPFs to evaluate the reliability of the resulting discharge forecasts, while an ensemble prediction system (EPS) based on perturbed atmospheric initial and boundary conditions has been designed to test the value of a probabilistic strategy versus the previous deterministic approach. Specifically, a Potential Vorticity (PV) Inversion technique has been used to perturb the MM5 model initial and boundary states (i.e. ECMWF forecast fields). For that purpose, a PV error climatology has been previously derived in order to introduce realistic PV perturbations in the EPS. Results show the benefits of using a probabilistic approach in those cases where the deterministic QPF presents significant deficiencies over the Llobregat river basin in terms of the rainfall amounts, timing and localization. These deficiences in precipitation fields have a major impact on flood forecasts. Our ensemble strategy has been found useful to reduce the biases at different hydrometric sections along the watershed. Therefore, in an operational context, the devised methodology could be useful to expand the lead times associated with the prediction of similar future floods, helping to alleviate their possible hazardous consequences.
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Amengual, A., R. Romero, M. Vich und S. Alonso. „Inclusion of potential vorticity uncertainties into a hydrometeorological forecasting chain: application to a medium size basin of Mediterranean Spain“. Hydrology and Earth System Sciences 13, Nr. 6 (17.06.2009): 793–811. http://dx.doi.org/10.5194/hess-13-793-2009.
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Abstract. The improvement of the short- and mid-range numerical runoff forecasts over the flood-prone Spanish Mediterranean area is a challenging issue. This work analyses four intense precipitation events which produced floods of different magnitude over the Llobregat river basin, a medium size catchment located in Catalonia, north-eastern Spain. One of them was a devasting flash flood – known as the "Montserrat" event – which produced 5 fatalities and material losses estimated at about 65 million euros. The characterization of the Llobregat basin's hydrological response to these floods is first assessed by using rain-gauge data and the Hydrologic Engineering Center's Hydrological Modeling System (HEC-HMS) runoff model. In second place, the non-hydrostatic fifth-generation Pennsylvania State University/NCAR mesoscale model (MM5) is nested within the ECMWF large-scale forecast fields in a set of 54 h period simulations to provide quantitative precipitation forecasts (QPFs) for each hydrometeorological episode. The hydrological model is forced with these QPFs to evaluate the reliability of the resulting discharge forecasts, while an ensemble prediction system (EPS) based on perturbed atmospheric initial and boundary conditions has been designed to test the value of a probabilistic strategy versus the previous deterministic approach. Specifically, a Potential Vorticity (PV) Inversion technique has been used to perturb the MM5 model initial and boundary states (i.e. ECMWF forecast fields). For that purpose, a PV error climatology has been previously derived in order to introduce realistic PV perturbations in the EPS. Results show the benefits of using a probabilistic approach in those cases where the deterministic QPF presents significant deficiencies over the Llobregat river basin in terms of the rainfall amounts, timing and localization. These deficiences in precipitation fields have a major impact on flood forecasts. Our ensemble strategy has been found useful to reduce the biases at different hydrometric sections along the watershed. Therefore, in an operational context, the devised methodology could be useful to expand the lead times associated with the prediction of similar future floods, helping to alleviate their possible hazardous consequences.
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Biavati, G., J. W. Godt und J. P. McKenna. „Drainage effects on the transient, near-surface hydrologic response of a steep hillslope to rainfall: implications for slope stability, Edmonds, Washington, USA“. Natural Hazards and Earth System Sciences 6, Nr. 3 (11.05.2006): 343–55. http://dx.doi.org/10.5194/nhess-6-343-2006.
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Abstract. Shallow landslides on steep (>25°) hillsides along Puget Sound have resulted in occasional loss of life and costly damage to property during intense or prolonged rainfall. As part of a larger project to assess landslide hazards in the Seattle area, the U.S. Geological Survey instrumented two coastal bluff sites in 2001 to observe the subsurface hydrologic response to rainfall. The instrumentation at one of these sites, near Edmonds, Washington, consists of two rain gauges, two water-content probes that measure volumetric water content at eight depths between 0.2 and 2.0 m, and two tensiometer nests that measure soil-water suction at six depths ranging from 0.2 to 1.5 m. Measurements from these instruments are used to test one- and two-dimensional numerical models of infiltration and groundwater flow. Capillary-rise tests, performed in the laboratory on soil sample from the Edmonds site, are used to define the soil hydraulic properties for the wetting process. The field observations of water content and suction show an apparent effect of porosity variation with depth on the hydraulic response to rainfall. Using a range of physical properties consistent with our laboratory and field measurements, we perform sensitivity analyses to investigate the effects of variation in physical and hydraulic properties of the soil on rainfall infiltration, pore-pressure response, and, hence, slope stability. For a two-layer-system in which the hydraulic conductivity of the upper layer is at least 10 times greater than the conductivity of the lower layer, and the infiltration rate is greater than the conductivity of the lower layer, a perched water table forms above the layer boundary potentially destabilizing the upper layer of soil. Two-dimensional modeling results indicate that the addition of a simple trench drain to the same two-layer slope has differing effects on the hydraulic response depending on the initial pressure head conditions. For slope-parallel flow conditions, pressure head is significantly reduced near the drain; however, for transient, vertical infiltration in a partially saturated soil, conditions consistent with those observed during monitoring at the Edmonds site, the drain decreases the thickness of a perched water table by a small amount.
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Cheng, Chad Shouquan, Guilong Li, Qian Li und Heather Auld. „A Synoptic Weather-Typing Approach to Project Future Daily Rainfall and Extremes at Local Scale in Ontario, Canada“. Journal of Climate 24, Nr. 14 (15.07.2011): 3667–85. http://dx.doi.org/10.1175/2011jcli3764.1.
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Abstract This paper attempts to project possible changes in the frequency of daily rainfall events late in this century for four selected river basins (i.e., Grand, Humber, Rideau, and Upper Thames) in Ontario, Canada. To achieve this goal, automated synoptic weather typing as well as cumulative logit and nonlinear regression methods was employed to develop within-weather-type daily rainfall simulation models. In addition, regression-based downscaling was applied to downscale four general circulation model (GCM) simulations to three meteorological stations (i.e., London, Ottawa, and Toronto) within the river basins for all meteorological variables (except rainfall) used in the study. Using downscaled GCM hourly climate data, discriminant function analysis was employed to allocate each future day for two windows of time (2046–65, 2081–2100) into one of the weather types. Future daily rainfall and its extremes were projected by applying within-weather-type rainfall simulation models together with downscaled future GCM climate data. A verification process of model results has been built into the whole exercise (i.e., statistical downscaling, synoptic weather typing, and daily rainfall simulation modeling) to ascertain whether the methods are stable for projection of changes in frequency of future daily rainfall events. Two independent approaches were used to project changes in frequency of daily rainfall events: method I—comparing future and historical frequencies of rainfall-related weather types, and method II—applying daily rainfall simulation models with downscaled future climate information. The increases of future daily rainfall event frequencies and seasonal rainfall totals (April–November) projected by method II are usually greater than those derived by method I. The increase in frequency of future daily heavy rainfall events greater than or equal to 25 mm, derived from both methods, is likely to be greater than that of future daily rainfall events greater than or equal to 0.2 mm: 35%–50% versus 10%–25% over the period 2081–2100 derived from method II. In addition, the return values of annual maximum 3-day accumulated rainfall totals are projected to increase by 20%–50%, 30%–55%, and 25%–60% for the periods 2001–50, 2026–75, and 2051–2100, respectively. Inter-GCM and interscenario uncertainties of future rainfall projections were quantitatively assessed. The intermodel uncertainties are similar to the interscenario uncertainties, for both method I and method II. However, the uncertainties are generally much smaller than the projection of percentage increases in the frequency of future seasonal rain days and future seasonal rainfall totals. The overall mean projected percentage increases are about 2.6 times greater than overall mean intermodel and interscenario uncertainties from method I; the corresponding projected increases from method II are 2.2–3.7 times greater than overall mean uncertainties.
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Pasculli, Antonio, Roberto Longo, Nicola Sciarra und Carmine Di Nucci. „Surface Water Flow Balance of a River Basin Using a Shallow Water Approach and GPU Parallel Computing—Pescara River (Italy) as Test Case“. Water 14, Nr. 2 (14.01.2022): 234. http://dx.doi.org/10.3390/w14020234.
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The analysis and prevention of hydrogeological risks plays a very important role and, currently, much attention is paid to advanced numerical models that correspond more to physical reality and whose aim is to reproduce complex environmental phenomena even for long times and on large spatial scales. Within this context, the feasibility of performing an effective balance of surface water flow relating to several months was explored, based on accurate hydraulic and mathematical-numerical models applied to a system at the scale of a hydrographic basin. To pursue this target, a 2D Riemann–Godunov shallow-water approach, solved in parallel on a graphical processing unit (GPU), able to drastically reduce calculation time, and implemented into the RiverFlow2D code (2017 version), was selected. Infiltration and evapotranspiration were included but in a simplified way, in order to face the calibration and validation simulations and because, despite the parallel approach, it is very demanding even for the computer time requirement. As a test case the Pescara river basin, located in Abruzzo, Central Italy, covering an area of 813 km2 and well representative of a typical medium-sized basin, was selected. The topography was described by a 10 × 10 m digital terrain model (DTM), covered by about 1,700,000 triangular elements, equipped with 11 rain gauges, distributed over the entire area, with some hydrometers and some fluviometric stations. Calibration, and validation were performed considering the flow data measured at a station located in close proximity to the mouth of the river. The comparison between the numerical and measured data, and also from a statistical point of view, was quite satisfactory. A further important outcome was the capability to highlight any differences between the numerical flow-rate balance carried out on the basis of the contributions of all known sources and the values actually measured. This characteristic of the applied modeling allows better calibration and verification not only of the effectiveness of much more simplified approaches, but also the entire network of measurement stations and could suggest the need for a more in-depth exploration of the territory in question. It would also enable the eventual identification of further hidden supplies of water inventory from underground sources and, accordingly, to enlarge the hydrographic and hydrogeological border of the basin under study. Moreover, the parallel computing platform would also allow the development of effective early warning systems, for example, of floods.
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De Oliveira Ferreira Silva, Cesar. „CLASSIFICAÇÃO SUPERVISIONADA DE ÁREA IRRIGADA UTILIZANDO ÍNDICES ESPECTRAIS DE IMAGENS LANDSAT-8 COM GOOGLE EARTH ENGINE“. IRRIGA 25, Nr. 1 (19.03.2020): 160–69. http://dx.doi.org/10.15809/irriga.2020v25n1p160-169.
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CLASSIFICAÇÃO SUPERVISIONADA DE ÁREA IRRIGADA UTILIZANDO ÍNDICES ESPECTRAIS DE IMAGENS LANDSAT-8 COM GOOGLE EARTH ENGINE
CÉSAR DE OLIVEIRA FERREIRA SILVA1
1 Departamento de Engenharia Rural, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista (UNESP) Campus de Botucatu. Avenida Universitária, n° 3780, Altos do Paraíso, CEP: 18610-034, Botucatu – SP, Brasil, e-mail: cesaroliveira.f.silva@gmail.com.
1 RESUMO
Identificar áreas de irrigação usando imagens de satélite é um desafio que encontra em soluções de computação em nuvem um grande potencial, como na ferramenta Google Earth Engine (GEE), que facilita o processo de busca, filtragem e manipulação de grandes volumes de dados de sensoriamento remoto sem a necessidade de softwares pagos ou de download de imagens. O presente trabalho apresenta uma implementação de classificação supervisionada de áreas irrigadas e não-irrigadas na região de Sorriso e Lucas do Rio Verde/MT com o algoritmo Classification and Regression Trees (CART) em ambiente GEE utilizando as bandas 2-7 do satélite Landsat-8 e os índices NDVI, NDWI e SAVI. A acurácia da classificação supervisionada foi de 99,4% ao utilizar os índices NDWI, NDVI e SAVI e de 98,7% sem utilizar esses índices, todas consideradas excelentes. O tempo de processamento médio, refeito 10 vezes, foi de 52 segundos, considerando todo o código-fonte desenvolvido desde a filtragem das imagens até a conclusão da classificação. O código-fonte desenvolvido é apresentado em anexo de modo a difundir e incentivar o uso do GEE para estudos de inteligência espacial em irrigação e drenagem por sua usabilidade e fácil manipulação.
Keywords: computação em nuvem, sensoriamento remoto, hidrologia, modelagem.
SILVA, C. O .F
SUPERVISED CLASSIFICATION OF IRRIGATED AREA USING SPECTRAL INDEXES FROM LANDSAT-8 IMAGES WITH GOOGLE EARTH ENGINE
2 ABSTRACT
Identifying irrigation areas using satellite images is a challenge that finds great potential in cloud computing solutions as the Google Earth Engine (GEE) tool, which facilitates the process of searching, filtering and manipulating large volumes of remote sensing data without the need for paid software or image downloading. The present work presents an implementation of the supervised classification of irrigated and rain-fed areas in the region of Sorriso and Lucas do Rio Verde/MT with the Classification and Regression Trees (CART) algorithm in GEE environment using bands 2-7 of the Landsat- 8 and the NDVI, NDWI and SAVI indices. The accuracy of the supervised classification was 99.4% when using NDWI, NDVI and SAVI indices and 98.7% without using these indices, which were considered excellent. The average processing time, redone 10 times, was 52 seconds, considering all the source code developed from the filtering of the images to the conclusion of the classification. The developed source code is available in the appendix in order to disseminate and encourage the use of GEE for studies of spatial intelligence in irrigation and drainage due to its usability and easy manipulation.
Keywords: cloud computing, remote sensing, hydrology, modeling.
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Losidis, Sotirios. „Covariance between the forward recurrence time and the number of renewals“. Modern Stochastics: Theory and Applications, 15.12.2021, 1–16. http://dx.doi.org/10.15559/21-vmsta194.
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Recurrence times and the number of renewals in $(0,t]$ are fundamental quantities in renewal theory. Firstly, it is proved that the upper orthant order for the pair of the forward and backward recurrence times may result in NWUC (NBUC) interarrivals. It is also demonstrated that, under DFR interarrival times, the backward recurrence time is smaller than the forward recurrence time in the hazard rate order. Lastly, the sign of the covariance between the forward recurrence time and the number of renewals in $(0,t]$ at a fixed time point t and when $t\to \infty $ is studied assuming that the interarrival distribution belongs to certain ageing classes.