Letteratura scientifica selezionata sul tema "Mean Areal Precipitation"
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Articoli di riviste sul tema "Mean Areal Precipitation"
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Hieu, Bui Thi. "Study on quantification of areal mean precipitation using satellite-gauge merging precipitation". Journal of Science and Technology in Civil Engineering (STCE) - NUCE 12, n. 5 (30 agosto 2018): 117–26. http://dx.doi.org/10.31814/stce.nuce2018-12(5)-12.
Testo completoAbstract (sommario):
Satellite based precipitation product (GSMaP-MVK) can be reliably used to estimate the Areal Mean Precipitation error based on “Sample Design method” (Esdd) with the effort to mitigate the problem of sparse data, especially severe in poorly gauged river basins. In addition, the satellite-gauge merging precipitation would reduce significantly the magnitude gaps between the satellite rainfall estimations and the rain gauge data. In this study, the capability of satellite-gauge merging precipitation using GSMaP-MVK and local dense rain gauge data with bias reduction approach to evaluate the AMP is investigated. The main finding is that satellite-gauge blending data which incorporates a dense rain gauge measurements shows the better capability to evaluate AMP using Esdd index than the original satellite only precipitation estimations. However, Esdd quantification performances of satellite-gauge blending precipitation are inferior to the original satellite only precipitation product GSMaP-MVK when the number of blended rain gauges is not large enough.
Keywords: areal mean precipitation; remote sensed precipitation product; satellite-gauge merging; rainfall runoff simulations.
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Fontaine, Thomas A. "PREDICTING MEASUREMENT ERROR OF AREAL MEAN PRECIPITATION DURING EXTREME EVENTS". Journal of the American Water Resources Association 27, n. 3 (giugno 1991): 509–20. http://dx.doi.org/10.1111/j.1752-1688.1991.tb01451.x.
Testo completo
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Garen, David C., Gregory L. Johnson e Clayton L. Hanson. "MEAN AREAL PRECIPITATION FOR DAILY HYDROLOGIC MODELING IN MOUNTAINOUS REGIONS". Journal of the American Water Resources Association 30, n. 3 (giugno 1994): 481–91. http://dx.doi.org/10.1111/j.1752-1688.1994.tb03307.x.
Testo completo
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Xu, Guoyin, Zhongjing Wang e Ting Xia. "Mapping Areal Precipitation with Fusion Data by ANN Machine Learning in Sparse Gauged Region". Applied Sciences 9, n. 11 (4 giugno 2019): 2294. http://dx.doi.org/10.3390/app9112294.
Testo completoAbstract (sommario):
Focusing on water resources assessment in ungauged or sparse gauged areas, a comparative evaluation of areal precipitation was conducted by remote sensing data, limited gauged data, and a fusion of gauged data and remote sensing data based on machine learning. The artificial neural network (ANN) model was used to fuse the remote sensing precipitation and ground gauge precipitation. The correlation coefficient, root mean square deviation, relative deviation and consistency principle were used to evaluate the reliability of the remote sensing precipitation. The case study in the Qaidam Basin, northwest of China, shows that the precision of the original remote sensing precipitation product of Tropical Precipitation Measurement Satellite (TRMM)-3B42RT and TRMM-3B43 was 0.61, 72.25 mm, 36.51%, 27% and 0.70, 64.24 mm, 31.63%, 32%, respectively, comparing with gauged precipitation. The precision of corrected TRMM-3B42RT and TRMM-3B43 improved to 0.89, 37.51 mm, –0.08%, 41% and 0.91, 34.22 mm, 0.11%, 42%, respectively, which indicates that the data mining considering elevation, longitude and latitude as the main influencing factors of precipitation is efficient and effective. The evaluation of areal precipitation in the Qaidam Basin shows that the mean annual precipitation is 104.34 mm, 186.01 mm and 174.76 mm based on the gauge data, corrected TRMM-3B42RT and corrected TRMM-3B43. The results show many differences in the areal precipitation based on sparse gauge precipitation data and fusion remote sensing data.
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Moulin, L., E. Gaume e C. Obled. "Uncertainties on mean areal precipitation: assessment and impact on streamflow simulations". Hydrology and Earth System Sciences Discussions 5, n. 4 (1 agosto 2008): 2067–110. http://dx.doi.org/10.5194/hessd-5-2067-2008.
Testo completoAbstract (sommario):
Abstract. This paper investigates the influence of mean areal rainfall estimation errors on a specific case study: the use of lumped conceptual rainfall-runoff models to simulate the flood hydrographs of three small to medium-sized catchments of the upper Loire river. This area (3200 km2) is densely covered by an operational network of stream and rain gauges. It is frequently exposed to flash floods and the improvement of flood forecasting models is then a crucial concern. Particular attention has been drawn to the development of an error model for rainfall estimation consistent with data in order to produce realistic streamflow simulation uncertainty ranges. The proposed error model combines geostatistical tools based on kriging and an autoregressive model to account for temporal dependence of errors. It has been calibrated and partly validated for hourly mean areal precipitation rates. Simulated error scenarios were propagated into two calibrated rainfall-runoff models using Monte Carlo simulations. Three catchments with areas ranging from 60 to 3200 km2 were tested to reveal any possible links between the sensitivity of the model outputs to rainfall estimation errors and the size of the catchment. The results show that a large part of the rainfall-runoff (RR) modelling errors can be explained by the uncertainties on rainfall estimates, especially in the case of smaller catchments. These errors are a major factor limiting accuracy and sharpness of rainfall-runoff simulations, and thus their operational use for flood forecasting.
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Moulin, L., E. Gaume e C. Obled. "Uncertainties on mean areal precipitation: assessment and impact on streamflow simulations". Hydrology and Earth System Sciences 13, n. 2 (4 febbraio 2009): 99–114. http://dx.doi.org/10.5194/hess-13-99-2009.
Testo completoAbstract (sommario):
Abstract. This paper investigates the influence of mean areal rainfall estimation errors on a specific case study: the use of lumped conceptual rainfall-runoff models to simulate the flood hydrographs of three small to medium-sized catchments of the upper Loire river. This area (3200 km2) is densely covered by an operational network of stream and rain gauges. It is frequently exposed to flash floods and the improvement of flood forecasting models is then a crucial concern. Particular attention has been drawn to the development of an error model for rainfall estimation consistent with data in order to produce realistic streamflow simulation uncertainty ranges. The proposed error model combines geostatistical tools based on kriging and an autoregressive model to account for temporal dependence of errors. It has been calibrated and partly validated for hourly mean areal precipitation rates. Simulated error scenarios were propagated into two calibrated rainfall-runoff models using Monte Carlo simulations. Three catchments with areas ranging from 60 to 3200 km2 were tested to reveal any possible links between the sensitivity of the model outputs to rainfall estimation errors and the size of the catchment. The results show that a large part of the rainfall-runoff (RR) modelling errors can be explained by the uncertainties on rainfall estimates, especially in the case of smaller catchments. These errors are a major factor limiting accuracy and sharpness of rainfall-runoff simulations, and thus their operational use for flood forecasting.
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Johnson, Dennis, Michael Smith, Victor Koren e Bryce Finnerty. "Comparing Mean Areal Precipitation Estimates from NEXRAD and Rain Gauge Networks". Journal of Hydrologic Engineering 4, n. 2 (aprile 1999): 117–24. http://dx.doi.org/10.1061/(asce)1084-0699(1999)4:2(117).
Testo completo
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Gagnon, P., A. N. Rousseau, A. Mailhot e D. Caya. "Spatial Disaggregation of Mean Areal Rainfall Using Gibbs Sampling". Journal of Hydrometeorology 13, n. 1 (1 febbraio 2012): 324–37. http://dx.doi.org/10.1175/jhm-d-11-034.1.
Testo completoAbstract (sommario):
Abstract Precipitation has a high spatial variability, and thus some modeling applications require high-resolution data (<10 km). Unfortunately, in some cases, such as meteorological forecasts and future regional climate projections, only spatial averages over large areas are available. While some attention has been given to the disaggregation of mean areal precipitation estimates, the computation of a disaggregated field with a realistic spatial structure remains a difficult task. This paper describes the development of a statistical disaggregation model based on Gibbs sampling. The model disaggregates 45.6-km-resolution rainfall fields to grids with pixel sizes ranging from 3.8 to 22.8 km. The model is conceptually simple, as the algorithm is straightforward to compute with only a few parameters to estimate. The rainfall depth at each grid pixel is related to the depths of the neighboring pixels, while the spatial variability is related to the convective available potential energy (CAPE) field. The model is developed using daily rainfall data over a 40 000-km2 area located in the southeastern United States. Four-kilometer-resolution rainfall estimates obtained from NCEP’s stage IV analysis were used to estimate the model parameters (2002–04) and as a reference to validate the disaggregated fields (2005/06). Results show that the model accurately simulates rainfall depths and the spatial structure of the observed field. Because the model has low computational requirements, an ensemble of disaggregated data series can be generated.
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Guven, Aytac, e Abdulhadi Pala. "Comparison of different statistical downscaling models and future projection of areal mean precipitation of a river basin under climate change effect". Water Supply 22, n. 3 (27 ottobre 2021): 2424–39. http://dx.doi.org/10.2166/ws.2021.372.
Testo completoAbstract (sommario):
Abstract Investigation of the hydrological impacts of climate change at the local scale requires the use of a statistical downscaling technique. In order to use the output of a Global Circulation Model (GCM), a downscaling technique is used. In this study, statistical downscaling of monthly areal mean precipitation in the Göksun River basin in Turkey was carried out using the Group Method of Data Handling (GMDH), Support Vector Machine (SVM) and Gene Expression Programming (GEP) techniques. Large-scale weather factors were used for the basin with a monthly areal mean precipitation (PM) record from 1971 to 2000 used for training and testing periods. The R2-value for precipitation in the SVM, GEP and GMDH models are 0.62, 0.59, and 0.6 respectively, for the testing periods. The results show that SVM has the best model performance of the three proposed downscaling models, however, the GEP model has the lowest AIC value. The simulated results for the Canadian GCM3 (CGCM3) A1B and A2 scenarios show a similarity in their average precipitation prediction. Generally, both these scenarios anticipate a decrease in the average monthly precipitation during the simulated periods. Therefore, the results of the future projections show that mean precipitation might decrease during the period of 2021–2100.
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Bumke, Karl, Robin Pilch Kedzierski, Marc Schröder, Christian Klepp e Karsten Fennig. "Validation of HOAPS Rain Retrievals against OceanRAIN In-Situ Measurements over the Atlantic Ocean". Atmosphere 10, n. 1 (7 gennaio 2019): 15. http://dx.doi.org/10.3390/atmos10010015.
Testo completoAbstract (sommario):
The satellite-derived HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data) precipitation estimates have been validated against in-situ precipitation measurements from optical disdrometers, available from OceanRAIN (Ocean Rainfall And Ice-phase precipitation measurement Network) over the open-ocean by applying a statistical analysis for binary estimates. In addition to using directly collocated pairs of data, collocated data were merged within a certain temporal and spatial threshold into single events, according to the observation times. Although binary statistics do not show perfect agreement, simulations of areal estimates from the observations themselves indicate a reasonable performance of HOAPS to detect rain. However, there are deficits at low and mid-latitudes. Weaknesses also occur when analyzing the mean precipitation rates; HOAPS underperforms in the area of the intertropical convergence zone, where OceanRAIN observations show the highest mean precipitation rates. Histograms indicate that this is due to an underestimation of the frequency of moderate to high precipitation rates by HOAPS, which cannot be explained by areal averaging.
Tesi sul tema "Mean Areal Precipitation"
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Maloku, Kaltrina. "Génération de séries temporelles infra-journalières de précipitations surfaciques moyennes partout en Suisse en combinant un générateur stochastique de précipitations journalières et une cascade aléatoire multiplicative". Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALU023.
Testo completoAbstract (sommario):
La simulation hydrométéorologique continue est une approche performante pour générer de longues chroniques de débits nécessaires à l'analyse du risque de crue. Cette approche nécessite de longues chroniques de précipitations en entrée qui peuvent être générées par un générateur météorologique stochastique. Pour les petits bassins versants (10-1000 km²) où un modèle hydrologique global est pertinent et où la réponse hydrologique peut être rapide, des scénarios infra-journaliers de précipitations surfaciques moyennes sont requis.Cette thèse étudie le potentiel d'un générateur météorologique hybride infra-journalier composé de deux modèles stochastiques. Le premier modèle (GWEX) est dédié à la génération de chroniques journalières. Il modélise les occurrences de précipitations avec une chaîne de Markov et les quantités de précipitations avec une distribution à queue lourde adaptée aux événements extrêmes. Le second modèle désagrège les scénarios journaliers à une résolution horaire.Nous proposons d’abord un nouveau modèle de désagrégation basé sur l'approche de la cascade aléatoire multiplicative microcanonique (MRC). Les propriétés du générateur de la cascade dépendent continuellement de l'échelle temporelle, de l'intensité des précipitations et d’un indice d'asymétrie des précipitations introduit pour tenir compte de la structure temporelle de la séquence locale des précipitations. Le modèle MRC est comparé à des versions précédentes basées sur la même approche. La performance des modèles est évaluée en désagrégeant les observations journalières de 81 stations pluviométriques suisses. La performance globale du modèle MRC est très satisfaisante à différentes résolutions temporelles. La prise en compte de l'asymétrie des précipitations améliore significativement la reproduction de l'autocorrélation, une caractéristique que les modèles précédents, basés sur cette approche, avaient du mal à reproduire.Nous évaluons ensuite la performance du modèle hybride à générer des chroniques de précipitations surfaciques moyennes pour différentes échelles spatiales (10-1000 km²). Les paramètres des modèles GWEX et MRC sont estimés à partir des chroniques de précipitations surfaciques moyennes observées. Celles-ci sont extraites de CombiPrecip, un produit de précipitations horaires de MétéoSuisse d’une résolution de 1 km², issu d’une fusion de données radars et de pluviomètres. La performance du modèle est testée en Suisse pour un ensemble de sites et d'échelles spatiales en générant de longs scénarios de précipitations puis en comparant leurs statistiques avec celles observées. Les résultats montrent une performance satisfaisante du modèle pour différentes échelles spatiales et temporelles.Enfin, nous comparons différentes approches pour estimer les paramètres du générateur météorologique infra-journalier qui permettront de l’appliquer partout en Suisse. D’abord, différents modèles d’interpolation spatiale basés sur le krigeage et les “Thin-Plate Splines” sont considérés pour l'interpolation des paramètres obtenus à partir des données des pluviomètres. Ces modèles donnent de très bons résultats. Ensuite, la possibilité d'estimer les paramètres à partir des données de CombiPrecip est étudiée. Plusieurs longs scénarios sont générés pour un ensemble de sites et nous estimons la capacité de ces approches à reconstituer différentes caractéristiques des précipitations observées. Les deux approches sont globalement équivalentes bien que certaines différences puissent être observées avec des variations saisonnières et régionales marquées.Le modèle hybride montre des performances satisfaisantes dans différents contextes d'évaluation. Il est parcimonieux et les paramètres peuvent être estimés de manière robuste, conduisant à une forte cohérence spatiale et saisonnière. Ce modèle est facile à mettre en œuvre avec des procédures rapides d'estimation des paramètres et de simulation, ce qui facilite les applications à des fins opérationnellesContinuous hydro-meteorological simulation is a powerful approach for generating the long-time series of river discharge required for flood risk analysis. This approach requires long precipitation time series as inputs, which can be generated by a stochastic weather generator (WGEN). For small catchments (10 - 1,000 km²), where a lumped hydrological model is relevant and the hydrological response can be rapid, sub-daily mean areal precipitation (MAP) scenarios are required.To answer these objectives, this PhD thesis investigates the potential of a hybrid sub-daily WGEN consisting of two stochastic models for that purpose. The first model, GWEX, is dedicated to generating daily time series. It models precipitation occurrences with a Markov chain and precipitation amounts with a heavy-tailed distribution adapted to extreme events. The second model disaggregates the daily scenarios to hourly resolution.In this PhD, we propose a new disaggregation model based on the microcanonical multiplicative random cascade (MRC) approach, where the properties of the cascade generator depend continuously on the temporal scale, the precipitation intensity, and a so-called precipitation asymmetry index, introduced to account for the temporal pattern of the local precipitation sequence. We compare this MRC model with previous versions based on a similar approach. The performance of the models is assessed by disaggregating daily observations from 81 rain gauge stations across Switzerland. The overall performance of this MRC model is very satisfactory at different temporal resolutions. Accounting for precipitation asymmetry significantly improves the reproduction of autocorrelation, which previous models based on this approach have struggled with.We evaluate the performance of the hybrid WGEN to generate mean areal precipitation (MAP) time series for different spatial scales ranging from 10 to 1,000 km². The parameters of GWEX and MRC are estimated on the observed MAP time series extracted from CombiPrecip, an hourly gridded precipitation product of MeteoSwiss based on radar and rain gauge measurements with a spatial resolution of 1 km². The performance of the model is tested for an ensemble of locations and spatial scales in Switzerland by generating long precipitation scenarios and comparing their statistics with the observed ones. The results show a satisfactory performance of the model for different spatial and temporal scales.Finally, we compare different approaches for obtaining the parameters of the sub-daily WGEN over Switzerland. Initially, different mapping models based on kriging and thin plate splines are considered for interpolation of the at-site parameter estimates obtained from the rain gauge data. The mapping models give very accurate results. Then, the possibility of estimating parameters from CombiPrecip data is investigated. Multiple and long scenarios are generated for an ensemble of locations and different precipitation characteristics are estimated on the scenarios to compare both approaches. Both approaches are generally equivalent, although some differences can be observed with marked seasonal and regional variations.The hybrid model shows satisfactory performance in different evaluation contexts. It is parsimonious and parameters can be robustly estimated, leading to a strong spatial and seasonal coherence. The model is easy to implement with fast estimation and simulation procedures, facilitating end-user applications
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Kandel, Dinesh Raj. "AN ANALYSIS OF THE RELATIONSHIP BETWEEN PRECIPITATION AND BANKFULL CHANNEL WIDTH". OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/743.
Testo completoAbstract (sommario):
This study is concerned with the effect that mean annual precipitation (P) has on the relationship between bankfull channel width (Wbf) and drainage area (Ada). Several other studies have been conducted in which relationships were developed for predicting Wbf as a function of Ada and P. In most cases, however, the relationships were developed for specific regions, e.g., physiographic regions. This study is unusual in that it evaluates the relationship between Wbf, Ada, and P over a broad area (i.e., across a range of geologic, terrestrial, and climatic environments). In one study, where a broad area was considered, the relationship between Wbf, Ada, and P was found to be linear. The dataset for this study was compiled from data in U.S. Geological Survey flood-flow-frequency reports, regional curve studies (i.e., studies in which Wbf vs. Ada relationships are developed) and other sources. A total of 435 sites that span across 12 states of the continental U.S. are represented in the dataset. Streams represented in the dataset are alluvial and have widths from 1 to 110 m, drainage areas from 0.50 to 22,000 km2, and mean annual precipitation depths ranging from 22 to 277 cm/yr. Data from the U.S. Environmental Protection Agency's Wadeable Streams Assessment study were employed in validating the results of this study. An analysis of covariance (ANCOVA) model was developed and it was determined that the intercept coefficient for the relationship between Wbf and Ada varies as follows: for P < 50 cm/yr the intercept coefficient (α) is constant; for 50 cm/yr ¡Ü P ¡Ü 100 cm/yr, α increases with P, and for P ¡Ý100 cm/yr, α is again constant. Across all values of P, the slope coefficient is constant (90% Confidence level). Changes in the relationship between Wbfand Ada are attributed to vegetation by noting that biome types changes from shrubland to forest as P increases from 50 to 100 cm/yr. These findings can be incorporated in regional curve studies and landscape evolution models (i.e., models which aim to integrate hydrology, land use history, geomorphology and climate change with models of vegetation succession).
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VanCleve, Dennis Dewain. "An intercomparison of mean areal Precipitation from Gauges and a Multisensor Procedure". 2006. http://etd.lib.fsu.edu/theses/available/etd-08112006-181543.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Florida State University, 2006.Advisor: Henry E. Fuelberg, Florida State University, College of Arts and Sciences, Dept.of Meteorology. Title and description from dissertation home page (viewed Jan. 23, 2007). Document formatted into pages; contains ix, 52 pages. Includes bibliographical references.
Libri sul tema "Mean Areal Precipitation"
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Räisänen, Jouni. Future Climate Change in the Baltic Sea Region and Environmental Impacts. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.634.
Testo completoAbstract (sommario):
The warming of the global climate is expected to continue in the 21st century, although the magnitude of change depends on future anthropogenic greenhouse gas emissions and the sensitivity of climate to them. The regional characteristics and impacts of future climate change in the Baltic Sea countries have been explored since at least the 1990s. Later research has supported many findings from the early studies, but advances in understanding and improved modeling tools have made the picture gradually more comprehensive and more detailed. Nevertheless, many uncertainties still remain.In the Baltic Sea region, warming is likely to exceed its global average, particularly in winter and in the northern parts of the area. The warming will be accompanied by a general increase in winter precipitation, but in summer, precipitation may either increase or decrease, with a larger chance of drying in the southern than in the northern parts of the region. Despite the increase in winter precipitation, the amount of snow is generally expected to decrease, as a smaller fraction of the precipitation falls as snow and midwinter snowmelt episodes become more common. Changes in windiness are very uncertain, although most projections suggest a slight increase in average wind speed over the Baltic Sea. Climatic extremes are also projected to change, but some of the changes will differ from the corresponding change in mean climate. For example, the lowest winter temperatures are expected to warm even more than the winter mean temperature, and short-term summer precipitation extremes are likely to become more severe, even in the areas where the mean summer precipitation does not increase.The projected atmospheric changes will be accompanied by an increase in Baltic Sea water temperature, reduced ice cover, and, according to most studies, reduced salinity due to increased precipitation and river runoff. The seasonal cycle of runoff will be modified by changes in precipitation and earlier snowmelt. Global-scale sea level rise also will affect the Baltic Sea, but will be counteracted by glacial isostatic adjustment. According to most projections, in the northern parts of the Baltic Sea, the latter will still dominate, leading to a continued, although decelerated, decrease in relative sea level. The changes in the physical environment and climate will have a number of environmental impacts on, for example, atmospheric chemistry, freshwater and marine biogeochemistry, ecosystems, and coastal erosion. However, future environmental change in the region will be affected by several interrelated factors. Climate change is only one of them, and in many cases its effects may be exceeded by other anthropogenic changes.
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Norrgård, Stefan. Changes in Precipitation Over West Africa During Recent Centuries. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.536.
Testo completoAbstract (sommario):
Water, not temperature, governs life in West Africa, and the region is both temporally and spatially greatly affected by rainfall variability. Recent rainfall anomalies, for example, have greatly reduced crop productivity in the Sahel area. Rainfall indices from recent centuries show that multidecadal droughts reoccur and, furthermore, that interannual rainfall variations are high in West Africa. Current knowledge of historical rainfall patterns is, however, fairly limited. A detailed rainfall chronology of West Africa is currently only available from the beginning of the 19th century. For the 18th century and earlier, the records are still sporadic, and an interannual rainfall chronology has so far only been obtained for parts of the Guinea Coast. Thus, there is a need to extend the rainfall record to fully understand past precipitation changes in West Africa.The main challenge when investigating historical rainfall variability in West Africa is the scarcity of detailed and continuous data. Readily available meteorological data barely covers the last century, whereas in Europe and the United States for example, the data sometimes extend back two or more centuries. Data availability strongly correlates with the historical development of West Africa. The strong oral traditions that prevailed in the pre-literate societies meant that only some of the region’s history was recorded in writing before the arrival of the Europeans in the 16th century. From the 19th century onwards, there are, therefore, three types of documents available, and they are closely linked to the colonization of West Africa. These are: official records started by the colonial governments continuing to modern day; regular reporting stations started by the colonial powers; and finally, temporary nongovernmental observations of various kinds. For earlier periods, the researcher depends on noninstrumental observations found in letters, reports, or travel journals made by European slave traders, adventurers, and explorers. Spatially, these documents are confined to the coastal areas, as Europeans seldom ventured inland before the mid-1800s. Thus, the inland regions are generally poorly represented. Arabic chronicles from the Sahel provide the only source of information, but as historical documents, they include several spatiotemporal uncertainties. Climate researchers often complement historical data with proxy-data from nature’s own archives. However, the West African environment is restrictive. Reliable proxy-data, such as tree-rings, cannot be exploited effectively. Tropical trees have different growth patterns than trees in temperate regions and do not generate growth rings in the same manner. Sediment cores from Lake Bosumtwi in Ghana have provided, so far, the best centennial overview when it comes to understanding precipitation patterns during recent centuries. These reveal that there have been considerable changes in historical rainfall patterns—West Africa may have been even drier than it is today.
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Nash, David. Changes in Precipitation Over Southern Africa During Recent Centuries. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.539.
Testo completoAbstract (sommario):
Precipitation levels in southern Africa exhibit a marked east–west gradient and are characterized by strong seasonality and high interannual variability. Much of the mainland south of 15°S exhibits a semiarid to dry subhumid climate. More than 66 percent of rainfall in the extreme southwest of the subcontinent occurs between April and September. Rainfall in this region—termed the winter rainfall zone (WRZ)—is most commonly associated with the passage of midlatitude frontal systems embedded in the austral westerlies. In contrast, more than 66 percent of mean annual precipitation over much of the remainder of the subcontinent falls between October and March. Climates in this summer rainfall zone (SRZ) are dictated by the seasonal interplay between subtropical high-pressure systems and the migration of easterly flows associated with the Intertropical Convergence Zone. Fluctuations in both SRZ and WRZ rainfall are linked to the variability of sea-surface temperatures in the oceans surrounding southern Africa and are modulated by the interplay of large-scale modes of climate variability, including the El Niño-Southern Oscillation (ENSO), Southern Indian Ocean Dipole, and Southern Annular Mode.Ideas about long-term rainfall variability in southern Africa have shifted over time. During the early to mid-19th century, the prevailing narrative was that the climate was progressively desiccating. By the late 19th to early 20th century, when gauged precipitation data became more readily available, debate shifted toward the identification of cyclical rainfall variation. The integration of gauge data, evidence from historical documents, and information from natural proxies such as tree rings during the late 20th and early 21st centuries, has allowed the nature of precipitation variability since ~1800 to be more fully explored.Drought episodes affecting large areas of the SRZ occurred during the first decade of the 19th century, in the early and late 1820s, late 1850s–mid-1860s, mid-late 1870s, earlymid-1880s, and mid-late 1890s. Of these episodes, the drought during the early 1860s was the most severe of the 19th century, with those of the 1820s and 1890s the most protracted. Many of these droughts correspond with more extreme ENSO warm phases.Widespread wetter conditions are less easily identified. The year 1816 appears to have been relatively wet across the Kalahari and other areas of south central Africa. Other wetter episodes were centered on the late 1830s–early 1840s, 1855, 1870, and 1890. In the WRZ, drier conditions occurred during the first decade of the 19th century, for much of the mid-late 1830s through to the mid-1840s, during the late 1850s and early 1860s, and in the early-mid-1880s and mid-late 1890s. As for the SRZ, markedly wetter years are less easily identified, although the periods around 1815, the early 1830s, mid-1840s, mid-late 1870s, and early 1890s saw enhanced rainfall. Reconstructed rainfall anomalies for the SRZ suggest that, on average, the region was significantly wetter during the 19th century than the 20th and that there appears to have been a drying trend during the 20th century that has continued into the early 21st. In the WRZ, average annual rainfall levels appear to have been relatively consistent between the 19th and 20th centuries, although rainfall variability increased during the 20th century compared to the 19th.
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Tibaldi, Stefano, e Franco Molteni. Atmospheric Blocking in Observation and Models. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190228620.013.611.
Testo completoAbstract (sommario):
The atmospheric circulation in the mid-latitudes of both hemispheres is usually dominated by westerly winds and by planetary-scale and shorter-scale synoptic waves, moving mostly from west to east. A remarkable and frequent exception to this “usual” behavior is atmospheric blocking. Blocking occurs when the usual zonal flow is hindered by the establishment of a large-amplitude, quasi-stationary, high-pressure meridional circulation structure which “blocks” the flow of the westerlies and the progression of the atmospheric waves and disturbances embedded in them. Such blocking structures can have lifetimes varying from a few days to several weeks in the most extreme cases. Their presence can strongly affect the weather of large portions of the mid-latitudes, leading to the establishment of anomalous meteorological conditions. These can take the form of strong precipitation episodes or persistent anticyclonic regimes, leading in turn to floods, extreme cold spells, heat waves, or short-lived droughts. Even air quality can be strongly influenced by the establishment of atmospheric blocking, with episodes of high concentrations of low-level ozone in summer and of particulate matter and other air pollutants in winter, particularly in highly populated urban areas.Atmospheric blocking has the tendency to occur more often in winter and in certain longitudinal quadrants, notably the Euro-Atlantic and the Pacific sectors of the Northern Hemisphere. In the Southern Hemisphere, blocking episodes are generally less frequent, and the longitudinal localization is less pronounced than in the Northern Hemisphere.Blocking has aroused the interest of atmospheric scientists since the middle of the last century, with the pioneering observational works of Berggren, Bolin, Rossby, and Rex, and has become the subject of innumerable observational and theoretical studies. The purpose of such studies was originally to find a commonly accepted structural and phenomenological definition of atmospheric blocking. The investigations went on to study blocking climatology in terms of the geographical distribution of its frequency of occurrence and the associated seasonal and inter-annual variability. Well into the second half of the 20th century, a large number of theoretical dynamic works on blocking formation and maintenance started appearing in the literature. Such theoretical studies explored a wide range of possible dynamic mechanisms, including large-amplitude planetary-scale wave dynamics, including Rossby wave breaking, multiple equilibria circulation regimes, large-scale forcing of anticyclones by synoptic-scale eddies, finite-amplitude non-linear instability theory, and influence of sea surface temperature anomalies, to name but a few. However, to date no unique theoretical model of atmospheric blocking has been formulated that can account for all of its observational characteristics.When numerical, global short- and medium-range weather predictions started being produced operationally, and with the establishment, in the late 1970s and early 1980s, of the European Centre for Medium-Range Weather Forecasts, it quickly became of relevance to assess the capability of numerical models to predict blocking with the correct space-time characteristics (e.g., location, time of onset, life span, and decay). Early studies showed that models had difficulties in correctly representing blocking as well as in connection with their large systematic (mean) errors.Despite enormous improvements in the ability of numerical models to represent atmospheric dynamics, blocking remains a challenge for global weather prediction and climate simulation models. Such modeling deficiencies have negative consequences not only for our ability to represent the observed climate but also for the possibility of producing high-quality seasonal-to-decadal predictions. For such predictions, representing the correct space-time statistics of blocking occurrence is, especially for certain geographical areas, extremely important.
Capitoli di libri sul tema "Mean Areal Precipitation"
1
Hsu, Chin-Fei. "Uncertainties in Estimating Areal Means: With Applications to NADP/NTN Data". In Acidic Precipitation, 295–302. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-3385-9_30.
Testo completo
2
Wijaya, I. Putu Krishna, Peeranan Towashiraporn, Anish Joshi, Susantha Jayasinghe, Anggraini Dewi e Md Nurul Alam. "Climate Change-Induced Regional Landslide Hazard and Exposure Assessment for Aiding Climate Resilient Road Infrastructure Planning: A Case Study in Bagmati and Madhesh Provinces, Nepal". In Progress in Landslide Research and Technology, Volume 1 Issue 1, 2022, 175–84. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-16898-7_12.
Testo completoAbstract (sommario):
AbstractNepal’s hilly and mountainous regions are highly susceptible to landslides triggered by extreme precipitations. The prevalence of such landslides has increased due to climate change-induced extreme hydro-meteorological conditions. These recurring landslides have significantly impacted the road transport infrastructure, which is the economic lifeline for cities and socio-economic mobility of rural communities in the hilly and mountainous regions of the country. This study modelled extreme rainfall scenarios for the current 1976–2005 baseline and future horizons of 2030, 2050, and 2080 to develop high-resolution 1 km × 1 km mean precipitation datasets under RCP4.5 and RCP8.5. Based on these extreme precipitation scenarios, we developed high-resolution landslide hazard models adopting integrated weighted index by combining the Frequency Ratio (FR) and Analytical Hierarchical Process (AHP) methods using multi-variate factors. The multi-variate factors included three terrain parameters—slope, aspect, and elevation; two soil parameters—lithology and soil type; two Euclidean distance parameters from the likely sources—distance from the lineaments and distance from the stream/river; an anthropogenic parameter—land use; and the climate parameter—the mean annual rainfall for four-time horizons and two RCPs. These parameters were spatially modelled and combined using the weighted overlay method to generate a landslide hazard model. As demonstration case studies, the landslide hazard models were developed for Bagmati and Madhesh provinces. The models were validated using the Receiver Operating Characteristic curve (ROC) approach, which showed a satisfactory 81–86% accuracy in the study area. Spatial exposure analysis of the road network assets under the Strategic Road Network (SRN) was completed for seven landslide hazard scenarios. In both Bagmati and Madhesh provinces, the exposure analysis showed that the proportion of road sections exposed to landslide hazard significantly increases for the future climate change scenarios compared to the current baseline scenario.
3
Hrvatin, Mauro, e Matija Zorn. "Climate and Discharge Trends, and Flood Hazard in Slovenia’s Dinaric Karst Region Since the Mid-Twentieth Century". In Environmental History, 339–74. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-56089-7_12.
Testo completoAbstract (sommario):
AbstractThe temperature, precipitation, and snow-cover data collected at the meteorological stations in the Slovenia’s Dinaric Karst region between 1961 and 2020 indicate rapid and clear climate change. During this period, temperatures increased by 2.5 °C on average, precipitation decreased by 50–400 mm on average, and the number of days with snow cover declined by 30–60%. Several studies have confirmed that these changes have a strong impact on water conditions. What is alarming is especially a decrease in the average minimum and mean discharges, and a downward trend can also be observed for many average maximum discharges.Over the past sixty years, the climate in Slovenia’s Dinaric Karst region has become warmer and drier, and there has been a significant reduction in the volume of water at most gauging stations in the area studied. Based on the trends described, a significantly smaller flood hazard would be expected, but data from the past decades suggest the opposite. The following are highlighted as possible reasons for the current flood hazard: upward trends in absolute maximum discharges in individual river basins, a slightly downward trend in absolute maximum discharges and their simultaneously greater variability, various forms of land development that used to be avoided due to the risk of flooding, and more frequent short-term extreme precipitation events causing flash floods on smaller streams.
4
Biastoch, Arne, Siren Rühs, Ioana Ivanciu, Franziska U. Schwarzkopf, Jennifer Veitch, Chris Reason, Eduardo Zorita et al. "The Agulhas Current System as an Important Driver for Oceanic and Terrestrial Climate". In Sustainability of Southern African Ecosystems under Global Change, 191–220. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-10948-5_8.
Testo completoAbstract (sommario):
AbstractThe Agulhas Current system around South Africa combines the dynamics of strong ocean currents in the Indian Ocean with eddy–mean flow interactions. The system includes an associated interoceanic transport towards the Atlantic, Agulhas leakage, which varies on both interannual and decadal timescales. Agulhas leakage is subject to a general increase under increasing greenhouse gases, with higher leakage causing a warming and salinification of the upper ocean in the South Atlantic. The far-field consequences include the impact of the Agulhas Current on the Benguela Upwelling system, a major eastern boundary upwelling system that supports a lucrative fishing industry. Through sea surface temperatures and associated air–sea fluxes, the Agulhas Current system also influences regional climate in southern Africa, leading to a heterogeneous pattern of rainfall over southern Africa and to a reduction of precipitation in most areas under global warming conditions. Changes in the Agulhas Current system and the regional climate also cause changes in regional sea-level and wind-induced waves that deviate from global trends. Combining these oceanic changes with extreme precipitation events, global warming can considerably amplify flood impacts along the coast of South Africa if no adaptation measures are implemented.
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Finch, Deborah M., Jack L. Butler, Justin B. Runyon, Christopher J. Fettig, Francis F. Kilkenny, Shibu Jose, Susan J. Frankel et al. "Effects of Climate Change on Invasive Species". In Invasive Species in Forests and Rangelands of the United States, 57–83. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45367-1_4.
Testo completoAbstract (sommario):
AbstractMean surface temperatures have increased globally by ~0.7 °C per century since 1900 and 0.16 °C per decade since 1970 (Levinson and Fettig 2014). Most of this warming is believed to result from increases in atmospheric concentrations of greenhouse gases produced by human activity. Temperature increases have been greater in winter than in summer, and there is a tendency for these increases to be manifested mainly by changes in minimum (nighttime low) temperatures (Kukla and Karl 1993). Changes in precipitation patterns have also been observed, but are more variable than those of temperature. Even under conservative emission scenarios, future climatic changes are likely to include further increases in temperature with significant drying (drought) in some regions and increases in the frequency and severity of extreme weather events (IPCC 2007). For example, multimodel means of annual temperature from climate projections predict an increase of 3–9 °C in the United States over the next century combined with reductions in summer precipitation in certain areas (Walsh et al. 2014). These changes will affect invasive species in several ways. Furthermore, climate change may challenge the way we perceive and consider nonnative invasive species, as impacts to some will change and others will remain unaffected; other nonnative species are likely to become invasive; and native species are likely to shift their geographic ranges into novel habitats.
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Mukwada, Geofrey, e Sarudzai Mutana. "Surviving the Limits Imposed by a Changing Climate: The Case of Urban Drought and Water Supply Sustainability in Phuthaditjhaba". In Sustainable Development Goals Series, 75–89. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-15773-8_6.
Testo completoAbstract (sommario):
AbstractIn urban environments, sustainable access to water resources depends on many factors, including climatic, social and economic conditions characterizing the surrounding environment. For urban areas in mountain environments these conditions are compounded by stressors resulting from climate change, such as drought, as well as physical remoteness, economic marginalization and poverty, phenomena which impose limits on access to water. Based on Sustainable Development Goals (SDGs) 1, 6 and 13, which were part of the 2030 Agenda for Sustainable Development adopted by UN member states in 2015, in this paper we assess the impact of urban drought on water security in the mountain city of Phuthaditjhaba, South Africa. World Meteorological Organization - Time Series (4.04) climate (precipitation and maximum temperature) data for Phuthaditjhaba were analysed for trends for the period between 1960 and 2019. Trends of Standardized Precipitation Index values and Maximum Temperatures were used to determine how climate change has affected Phuthaditjhaba’s sources of water supply, namely the Fika Patso and Metsimatsho dams. A sample of Landsat images from the same period was used to determine how the two water bodies have responded to the change over time. The results indicate that the two reservoirs have shrunk due to climate change induced drought, thus worsening water insecurity in the city. The results also indicate that mean annual stream discharge is projected to decrease by 39% for the 2016–2045 period. Lastly, based on government reports on water shortages in Phuthaditjhaba and other secondary sources, the results also indicate that though 90% of Phuthaditjhaba’s population has access to potable water, only 55% of the residents have access to reliable water supply. We conclude that without urgent government intervention the future of the livelihoods of the poor majority of Phuthaditjhaba’s residents will remain bleak due to dwindling water resources, making SDG 6, and those influenced by it, unattainable.
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Kuria, Peter, Josiah Gitari, Saidi Mkomwa e Peter Waweru. "Effect of conservation agriculture on soil properties and maize grain yield in the semi-arid Laikipia county, Kenya." In Conservation agriculture in Africa: climate smart agricultural development, 256–69. Wallingford: CABI, 2022. http://dx.doi.org/10.1079/9781789245745.0015.
Testo completoAbstract (sommario):
Abstract Low and unreliable rainfall, along with poor soil health, is a main constraint to maize production in the semi-arid parts of Kenya that account for over 79% of the country's land area. In the vast county of Laikipia, farmers continue to plant maize despite the predominantly low quantities of precipitation. Participatory farmer experimentation with Conservation Agriculture (CA) was undertaken for six consecutive growing seasons between July 2013 and December 2016 to determine the effectiveness of CA as a method of improving soil properties and enhancing maize yields with the limited rainfall quantities received in these parts of Kenya. The main CA practices tested include chisel tine furrow opening (ripping) and live legume (Lablab purpureus) cover crop, as well as maize stover mulches, all implemented under varying inorganic fertilizer rates. The research was done across 12 administrative locations of Laikipia County where soils are mainly Phaeozems and Vertisols with a clay-loam texture. The research design used was researcher-designed and farmer-managed. In each of the 12 trial sites, participatory farmers' assessments and field days were carried out as a way of outreach to the bigger farming communities around the trial sites. The research findings obtained demonstrated that the use of CA impacts positively on soil properties and is a viable practice for enhancing maize yields in these moisture deficit-prone parts of the country. Soil chemical analysis assessment results showed that CA impacted positively on a number of soil mineral components including organic carbon, total nitrogen, phosphorus, potassium, calcium and pH. Midseason chlorophyll content assessment of the maize crop showed that there was good response to fertilizer application, as well as to mulching with crop residues for soil cover. Maize grain yield data also showed that the use of a CA package comprising chisel tine ripping combined with mulching by plant residues and use of mineral fertilizer resulted in a two- to threefold increase in grain yields above the farmer practice control. Mean maize grain yield in farmer practice plots was 1067 kg ha-1 compared with the CA-treated plot with mineral fertilization that yielded 2192 kg ha-1.
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Teegavarapu, Ramesh S. V. "Mean areal precipitation estimation: methods and issues". In Rainfall, 217–60. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-12-822544-8.00001-9.
Testo completo
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Saini, Rohtash, Nischal Sharma e Raju Attada. "Delving into Recent Changes in Precipitation Patterns in the Western Himalayas under Global Warming". In Global Warming - A Concerning Component of Climate Change [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.1002028.
Testo completoAbstract (sommario):
Western Himalayas (WH) have experienced a two-fold temperature increase compared to the Indian sub-continent post-2000, strongly linked to global warming with significant implications for precipitation patterns. Using ERA5 reanalysis, we examine seasonal precipitation changes in the WH between recent (2001–2020) and past decades (1961–2000). Mean summer precipitation has increased over foothills but declined at higher elevations, while winter precipitation has increased region-wide except in certain parts of Jammu-Kashmir (JK), Uttarakhand (UK), and Punjab. In summer, light precipitation has increased in JK, while moderate precipitation has decreased over foothills but enhanced at higher altitudes. Moreover, extreme precipitation has significantly increased in the UK and Himachal Pradesh. During winter, light and extreme precipitation has increased, while moderate and heavy precipitation declined. Maximum one and five-day precipitation extremes (Rx1day, Rx5day) have increased in the foothills with more consecutive wet days. Winter extremes have increased in the northern region, while consecutive dry and wet days have declined, except for specific areas in eastern Ladakh and JK. Furthermore, rising sea surface temperatures, enhanced moisture transport, increased precipitable water and cloud cover in WH are associated with increasing mean and extreme precipitation, emphasizing the impacts of global warming on temperature and precipitation transitions in the region.
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Rokade, Komal Gangaram, Prajakta Babasaheb Labade e B. K. Gavit. "ANALYSIS OF RAIN GAUGE CHARTS FOR DIFFERENT INTENSITY". In Futuristic Trends in Agriculture Engineering & Food Sciences Volume 3 Book 15, 188–94. Iterative International Publisher, Selfypage Developers Pvt Ltd, 2024. http://dx.doi.org/10.58532/v3bcag15p2ch5.
Testo completoAbstract (sommario):
The distribution and variation of rainfall over time in a specific area are referred to as rainfall patterns. These patterns are impacted by a number of variables, including topography, geography, climate, and atmospheric conditions, and they can differ significantly from one location to another. The tool used to measure rainfall is called a rain gauge. The measured precipitation is known as the point precipitation. The mean aerial rainfall is calculated from the point rainfall using a variety of computation techniques. By multiplying the mean depth of rainfall, watershed area, and region, the mean aerial rainfall may be used to calculate the amount of rainwater received over the watershed's surface. A Rainy day is considered to be rainfall of 2.5 mm rainfall or more than 2.5mm. By using the analysis of rain gauge charts the 30-minute rainfall intensity can be calculated.
Atti di convegni sul tema "Mean Areal Precipitation"
1
VanCleve, Jr., D. D., H. E. Fuelberg, Jan Mandrup-Poulsen e T. S. Wu. "An Intercomparison between Mean Areal Precipitation from Gauges and a Multi-Sensor Procedure". In World Environmental and Water Resources Congress 2007. Reston, VA: American Society of Civil Engineers, 2007. http://dx.doi.org/10.1061/40927(243)277.
Testo completo
2
Vuksanović, Darko, Dragan Radonjić e Jelena Šćepanović. "Influence of quarry rainwater on environmental quality". In 45. Međunarodna konferencija "Vodovod i kanalizacija '24" - zbornik radova, 385–96. Union of Engineers and Technicians of Serbia, Belgrade, 2024. http://dx.doi.org/10.5937/vik24385v.
Testo completoAbstract (sommario):
The quarries, due to their area of exploitation, generate stormwater that needs to be dealt with in a legally regulated manner, in order to protect the environment. When examining each surface mine, it is necessary to determine in detail whether there are surface and underground streams at the location and in the surrounding area. Usually, the location of the quarry, that is, the exploitation field is located in a limestone area, so surface water that occurs due to precipitation must be dealt with in an appropriate manner, due to the very technological process that takes place at the quarry. At quarries, due to their area of exploitation, rainwater is generated, which needs to be dealt with in a legally regulated manner, in order to protect the environment. When examining each surface mine, it is necessary to determine in detail whether there are surface and underground streams at the location and in the surrounding area. Usually, the location of the quarry, that is, the exploitation field is located in a limestone area, so surface water that occurs due to precipitation must be dealt with in an appropriate way, due to the very technological process that takes place at the quarry. In order to be able to make an adequate calculation of precipitation water, multi-year monitoring of precipitation in a given area is carried out, namely: • mean annual amount of precipitation, • annual fluctuation of precipitation, • the highest rainfall for the month in the monitoring year, • maximum daily precipitation, • maximum hourly precipitation. The aim of the work is to show how important it is to collect rainwater from quarries, in order to resolve their further treatment and discharge into the recipient, for the reason that these waters can be significantly contaminated, so their discharge without prior treatment could have a significant negative impact. impact on the quality of the environment.
3
Karaev, Vladimir, Leonid Mitnik, Maria Panfilova, Maria Ryabkova, Eugeny Meshkov, Yury Titchenko e Anton Yablokov. "Mean Square Slopes Of Sea Waves In Cyclone Area From Dual-Frequency Precipitation Radar And Microwave Radiometer". In IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2019. http://dx.doi.org/10.1109/igarss.2019.8899270.
Testo completo
4
Wallevik, K., J. Inger-slev e S. Stenbjerg Bernvil. "BLOOD BANK PRODUCTION OF HIGH YIELD, HIGH PURITY, HEAT TREATED F VIII CONCENTRATE FROM HEPARINIZED BLOOD". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643970.
Testo completoAbstract (sommario):
Applying trivial blood bank equipment we have developed a method to produce a heat-treated factor VIII concentrate from heparinized blood with an over-all yield between 40 and 50%, a specific activity around 2 i.u./mg and a low fibrinogen content (3-4 g/1). Electrophoretic multimer analysis of the von Wille-brand factor reveals a band pattern close to that of native plasma. The in vivo recovery is 99±25% and t/2 11.4±2.4 h (n=5). The method includes 3 precipitations in commercial "blood-bag" systems: (1) The classical cryoprecipitation, (2) Precipitation at 0°C of "cold insoluble globulins" including F VUI/vWf, (3) Precipitation of non F VIII/vWf related proteins at 10°C, pH 7.0 and specified ionic conditions.The F VIII rich supernatant is stabilized by amino acids and citrate, freeze dried, and heated to 68°C for 24 h.In our blood bank with ∼40,000 donations per year we have in a year produced ∼1,4 mill i.u. of the High Purity F VIII concentrate. This means that around 16,000 donations per year are collected in heparin, and that F VIII depleted plasma which we deliver for clinical use, either as liquid plasma or as a freeze-dridd product, contains solely heparin (∼4 i.u./ml) as anticoagulant.The method is technically simple which together with the high yield and high purity of the F VIII concentrate makes the production economically profitable. The method is applicable in areas with limited technical resources.We find it also important that F VIII concentrate, manufactured locally from healthy voluntary donors with personal attachment to their blood bank reveals the lowest risk for transmission of diseases to the patients.
5
Varenik, Alla, Alla Varenik, Sergey Konovalov e Sergey Konovalov. "ATMOSPHERIC N DEPOSITION TO THE COASTAL AREA OF THE BLACK SEA: SOURCES, INTRA-ANNUAL VARIATIONS AND IMPORTANCE FOR BIOGEOCHEMISTRY AND PRODUCTIVITY OF THE SURFACE LAYER". In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.31519/conferencearticle_5b1b945160eed9.16985540.
Testo completoAbstract (sommario):
Atmospheric precipitations can be an important source of nutrients to open and coastal zones of marine ecosystem. Jickells [1] has published that atmospheric depositions can sup-port 5-25% of nitrogen required to primary production. Bulk atmospheric precipitations have been collected in a rural location at the Black Sea Crimean coast – Katsiveli settlement, and an urban location – Sevastopol city. Samples have been analyzed for inorganic fixed nitrogen (IFN) – nitrate, nitrite, and ammonium. Deposi-tions have been calculated at various space and time scales. The monthly volume weighted mean concentration of IFN increases from summer to winter in both locations. A significant local source of IFN has been revealed for the urban location and this source and its spatial influence have been quantified. IFN deposition with atmospheric precipitations is up to 5% of its background content in the upper 10 m layer of water at the north-western shelf of the Black Sea. Considering Redfield C:N ratio (106:16) and the rate of primary production (PP) in coastal areas of the Black Sea of about 100-130 g C m-2 year-1 we have assessed that average atmospheric IFN depositions may intensify primary production by 4.5% for rural locations, but this value is increased many-fold in urban locations due to local IFN sources.
6
Varenik, Alla, Alla Varenik, Sergey Konovalov e Sergey Konovalov. "ATMOSPHERIC N DEPOSITION TO THE COASTAL AREA OF THE BLACK SEA: SOURCES, INTRA-ANNUAL VARIATIONS AND IMPORTANCE FOR BIOGEOCHEMISTRY AND PRODUCTIVITY OF THE SURFACE LAYER". In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.21610/conferencearticle_58b43155bc901.
Testo completoAbstract (sommario):
Atmospheric precipitations can be an important source of nutrients to open and coastal zones of marine ecosystem. Jickells [1] has published that atmospheric depositions can sup-port 5-25% of nitrogen required to primary production. Bulk atmospheric precipitations have been collected in a rural location at the Black Sea Crimean coast – Katsiveli settlement, and an urban location – Sevastopol city. Samples have been analyzed for inorganic fixed nitrogen (IFN) – nitrate, nitrite, and ammonium. Deposi-tions have been calculated at various space and time scales. The monthly volume weighted mean concentration of IFN increases from summer to winter in both locations. A significant local source of IFN has been revealed for the urban location and this source and its spatial influence have been quantified. IFN deposition with atmospheric precipitations is up to 5% of its background content in the upper 10 m layer of water at the north-western shelf of the Black Sea. Considering Redfield C:N ratio (106:16) and the rate of primary production (PP) in coastal areas of the Black Sea of about 100-130 g C m-2 year-1 we have assessed that average atmospheric IFN depositions may intensify primary production by 4.5% for rural locations, but this value is increased many-fold in urban locations due to local IFN sources.
7
Kirsta, Yu B., A. V. Puzanov, T. A. Rozhdestvenskaya e M. P. Peleneva. "Long-term forecast of heavy metals content in wheat grain under changing climate conditions". In Spatial Data Processing for Monitoring of Natural and Anthropogenic Processes 2021. Crossref, 2021. http://dx.doi.org/10.25743/sdm.2021.58.67.055.
Testo completoAbstract (sommario):
Using the system approach, we have developed a simulation model for the long-term forecast of the content of toxic chemical elements in grain crop yield. The study was carried out by the example of wheat cultivated in Altai Krai — one of the main grain-producing regions of Russia. Wheat crops were sampled in 10 municipal districts of Altai Krai, which characterize seven different edaphic-climatic zones. The average long-term values of mean monthly air temperature and monthly precipitation for each sampling area were identified using GIS and data of the Interactive Agricultural Ecological Atlas of Russia and Neighboring Countries. A total of 19 chemical elements were considered, i.e. Pb, As, Cd, Hg, Na, Mn, Zn, Cu, Fe, Co, etc. It is shown that content of Pb, Na, Mn and Cu in wheat depend on climatic characteristics of the cultivation area. Regression dependences of element content on the average long-term air temperature and precipitation were established. Based on normalization and spatial generalization of air temperature and precipitation providing the uniform dynamics of their relative monthly values (in percent) throughout the study area, a forecast of their changes was made for 2030. A procedure for grain sampling, GIS technologies for processing meteorological and cartographic data, methods for predicting regional climate changes and establishment of quantitative relationships of chemical elements content in grain with climatic characteristics – all together make up the integral predictive simulation model for toxic substance content in grain crop yield. The model was used for estimation of Pb, Na, Mn, Cu changes in wheat by 2030. The lead (Pb) content in wheat crop delivered to elevators from certain municipal districts will exceed the maximum allowable concentration for breadgrain after 2030. Unlike Pb, Na, Mn, Cu, the content of other metals in wheat grain weakly correlate with long-term changes in air temperature and precipitation; therefore, it can hardly change significantly.
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Ponomarev, Vladimir, Vladimir Ponomarev, Elena Dmitrieva, Elena Dmitrieva, Svetlana Shkorba, Svetlana Shkorba, Irina Mashkina, Irina Mashkina, Alexander Karnaukhov e Alexander Karnaukhov. "CLIMATIC REGIME CHANGE IN THE ASIAN PACIFIC REGION, INDIAN AND SOUTHERN OCEANS AT THE END OF THE 20TH CENTURY". In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.31519/conferencearticle_5b1b9475504153.46587602.
Testo completoAbstract (sommario):
Multiple scale climate variability in Asia of temperate and high latitudes, Pacific, Indian and South Oceans, their features and linkages are studied by using statistical analyses of monthly mean time series of Hadley, Reynolds SST, surface net heat flux (Q), atmospheric pressure (SLP), air temperature (SAT) from NCEP NCAR reanalyses (1948-2015). Three multidecadal climatic regimes were revealed for the whole area studied by using cluster analyses via Principal Components of differences between values of Q, SLP, SAT in tropical and extratropical regions of the Asian Pacific, Indian and Southern Oceans. The climate regime change in 70s of the 20th century in this area is confirmed by this method. It is also found that the climate regime is significantly changed at the end of the 20th century in both same area and World Ocean. The characteristic features of recent climate regime after 1996-1998 are SLP increase in the central extratropic area of Indian Ocean, North and South Pacific being prevailing in boreal winter. It is accompanying SLP increase and precipitation decrease in South Siberia and Mongolia prevailing in boreal summer. Inversed SLP and precipitation anomaly associated with increase of cyclone activity and extreme events in the land-ocean marginal zones including Southern Ocean, eastern Arctic, eastern Indian, western and eastern Pacific margins. It is known that low frequency PDO phase is also changed at the same time.
9
Ponomarev, Vladimir, Vladimir Ponomarev, Elena Dmitrieva, Elena Dmitrieva, Svetlana Shkorba, Svetlana Shkorba, Irina Mashkina, Irina Mashkina, Alexander Karnaukhov e Alexander Karnaukhov. "CLIMATIC REGIME CHANGE IN THE ASIAN PACIFIC REGION, INDIAN AND SOUTHERN OCEANS AT THE END OF THE 20TH CENTURY". In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.21610/conferencearticle_58b4316b52a9b.
Testo completoAbstract (sommario):
Multiple scale climate variability in Asia of temperate and high latitudes, Pacific, Indian and South Oceans, their features and linkages are studied by using statistical analyses of monthly mean time series of Hadley, Reynolds SST, surface net heat flux (Q), atmospheric pressure (SLP), air temperature (SAT) from NCEP NCAR reanalyses (1948-2015). Three multidecadal climatic regimes were revealed for the whole area studied by using cluster analyses via Principal Components of differences between values of Q, SLP, SAT in tropical and extratropical regions of the Asian Pacific, Indian and Southern Oceans. The climate regime change in 70s of the 20th century in this area is confirmed by this method. It is also found that the climate regime is significantly changed at the end of the 20th century in both same area and World Ocean. The characteristic features of recent climate regime after 1996-1998 are SLP increase in the central extratropic area of Indian Ocean, North and South Pacific being prevailing in boreal winter. It is accompanying SLP increase and precipitation decrease in South Siberia and Mongolia prevailing in boreal summer. Inversed SLP and precipitation anomaly associated with increase of cyclone activity and extreme events in the land-ocean marginal zones including Southern Ocean, eastern Arctic, eastern Indian, western and eastern Pacific margins. It is known that low frequency PDO phase is also changed at the same time.
10
Müller, Detlef, Albert Ansmann, Ulla Wandinger e Dietrich Althausen. "Retrieval of Microphysical Particle Properties from Backscatter and Extinction Data by Inversion via Regularization". In Optical Remote Sensing of the Atmosphere. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/orsa.1997.otub.3.
Testo completoAbstract (sommario):
Atmospheric aerosols, although only a minor constituent of the earth’s atmosphere, play an important role in many atmospheric processes. They have appreciable influence on the earth’s radiation budget, air quality, clouds and precipitation as well as the chemistry of the troposphere and stratosphere. One of the key aspects in a further understanding of the importance of aerosols is the investigation of the spatial and temporal variability of the particles’ microphysical properties, such as parameters describing their mean size, mass and surface-area concentrations. A data-evaluation algorithm that uses the method of inversion via regularization is currently being developed to retrieve microphysical parameters from optical data. Hereby, the main focus will be the information on mean values of the particle size distribution. The optical information will be provided by two lidar systems, a multiple wavelength lidar and a Raman lidar. Altogether, these systems will give six backscatter coefficients and two extinction coefficients in the wavelength range from 0.355 to 1.064 μm. Additional information will come from depolarization and water vapor measurements at 0.532 μm.
Rapporti di organizzazioni sul tema "Mean Areal Precipitation"
1
Parfenova, Elena. Database "Climate parameters of seed provenances of pine in northern eurasia". SIB-Expertise, dicembre 2020. http://dx.doi.org/10.12731/sib-expertise-0351-25122020.
Testo completoAbstract (sommario):
Database is created for pine (Pinus sylvestris L.) seeds weight from different habitats of northern Eurasia. Each database record consists of the following fields: latitude, longitude, July temperature, January temperature, mean annual temperature, annual precipitation, precipitation of vegetation period, growing degree days of vegetation period, degree days of winter period. Database is of 200 records long distributed along the whole area of pine in northern Eurasia.
2
Ruosteenoja, Kimmo. Applicability of CMIP6 models for building climate projections for northern Europe. Finnish Meteorological Institute, settembre 2021. http://dx.doi.org/10.35614/isbn.9789523361416.
Testo completoAbstract (sommario):
In this report, we have evaluated the performance of nearly 40 global climate models (GCMs) participating in Phase 6 of the Coupled Model Intercomparison Project (CMIP6). The focus is on the northern European area, but the ability to simulate southern European and global climate is discussed as well. Model evaluation was started with a technical control; completely unrealistic values in the GCM output files were identified by seeking the absolute minimum and maximum values. In this stage, one GCM was rejected totally, and furthermore individual output files from two other GCMs. In evaluating the remaining GCMs, the primary tool was the Model Climate Performance Index (MCPI) that combines RMS errors calculated for the different climate variables into one index. The index takes into account both the seasonal and spatial variations in climatological means. Here, MCPI was calculated for the period 1981—2010 by comparing GCM output with the ERA-Interim reanalyses. Climate variables explored in the evaluation were the surface air temperature, precipitation, sea level air pressure and incoming solar radiation at the surface. Besides MCPI, we studied RMS errors in the seasonal course of the spatial means by examining each climate variable separately. Furthermore, the evaluation procedure considered model performance in simulating past trends in the global-mean temperature, the compatibility of future responses to different greenhouse-gas scenarios and the number of available scenario runs. Daily minimum and maximum temperatures were likewise explored in a qualitative sense, but owing to the non-existence of data from multiple GCMs, these variables were not incorporated in the quantitative validation. Four of the 37 GCMs that had passed the initial technical check were regarded as wholly unusable for scenario calculations: in two GCMs the responses to the different greenhouse gas scenarios were contradictory and in two other GCMs data were missing from one of the four key climate variables. Moreover, to reduce inter-GCM dependencies, no more than two variants of any individual GCM were included; this led to an abandonment of one GCM. The remaining 32 GCMs were divided into three quality classes according to the assessed performance. The users of model data can utilize this grading to select a subset of GCMs to be used in elaborating climate projections for Finland or adjacent areas. Annual-mean temperature and precipitation projections for Finland proved to be nearly identical regardless of whether they were derived from the entire ensemble or by ignoring models that had obtained the lowest scores. Solar radiation projections were somewhat more sensitive.
3
Leis, Sherry, e Lloyd Morrison. Plant community trends at Tallgrass Prairie National Preserve: 1998–2018. National Park Service, ottobre 2022. http://dx.doi.org/10.36967/2294512.
Testo completoAbstract (sommario):
The Heartland Inventory and Monitoring Network monitors plant communities at Tallgrass Prairie National Preserve and evaluates a variety of environmental variables that affect vegetation patterns, including climate and ecological disturbances such as fire and grazing. Here we report on 2002–2018 trends in management actions (fire and grazing) and key plant community indicators. Temperature has increased over the past 50 years in the region. Precipitation and a standardized precipitation-evapotranspiration index included a high degree of interannual variability and did not demonstrate directional change. We documented a decline in disturbance intensity (i.e., less frequent prescribed fire and lower stocking rates) since 2006. A preserve goal is to maintain 30 to 60% of the area as bare ground (soil and rock) for ideal greater prairie-chicken habitat. Bare areas have been in decline and minimally meet the goal preserve wide. Bare areas vary by pasture and year, with bare areas exceeding the threshold in earlier years and Big Pasture and Red House Pasture falling short in some recent years. Although the preserve-scale mean minimally met the objective, there was a great deal of heterogeneity across monitoring sites. Litter cover and depth were greater than ecological recommendations for the greater prairie-chicken, especially in 2018. Litter depth demonstrated a great deal of variability and included deep litter. Woody plants were targeted to remain below 5% cover. Preserve- and pasture-scale cover means were well below this threshold but are increasing. Species richness on a per site basis (alpha diversity) and preserve-wide richness (gamma diversity) showed no apparent directional change when corrected for differences in sample size. Comparison of native species composition between 2002 and 2018 revealed a 36.9% difference in the Sørensen Index, although observer error accounted for almost 2/3 of this apparent change. The preserve continues to have characteristic tallgrass prairie species, and nonnative species continue to be low. Similar to targeted invasive plant monitoring, we found the target species Kentucky bluegrass to be below park thresholds. Continued evaluation of fire frequency and grazing intensity will be critical to achieving ecological goals including conserving the greater prairie-chicken. Development of a grazing plan may assist with prescribing stocking rates that are consistent with the preserve’s ecological and cultural objectives and could include alternative herbivores, such as goats or expansion of bison.
4
Spence, John, Ken Hyde e Vanessa Glynn-Linaris. 1995–2017 analysis of vegetation change using NDVI data at Glen Canyon National Recreation Area: Focused condition assessment report. National Park Service, giugno 2023. http://dx.doi.org/10.36967/2299497.
Testo completoAbstract (sommario):
This Focused Condition Assessment examines the impacts of the recent 2000–2020 long-term drought on the vegetation and soils of Glen Canyon National Recreation Area (GLCA). With support from the NASA DEVELOP Program, summer (June–August) Normalized Difference Vegetation Index (NDVI) values from 1995 to 2017 (excluding 2012 which was not available), measuring greenness and phenology in the vegetation, were analyzed for two periods. The first period from 1995–1999 included the pre-drought period, when precipitation was average to above average. Most years of the second period, 2000–2020, were drier than average as part of the severe drought that began in late 1999 and has continued to present (Lukas and Payton 2020). The NDVI values included mean values and were analyzed for 42 soil units, 20 associated NRCS Ecological Sites (ecosites), and the 10 most widespread vegetation alliances derived from the GLCA vegetation classification. Unvegetated rock outcrops, other exposed bedrock areas, and cliffs, which are extensive in GLCA, were not included. With the exception of some riparian areas, mean NDVI values for all upland soils, ecosites and alliances declined from pre-drought conditions. The areas showing the largest declines were clay soils, shallow sandy loam and other shallow soils and associated ecosites and alliances. Talus vegetation and mid- to upper elevation pinyon-juniper (Pinus edulis-Juniperus osteosperma) woodlands showed the smallest declines. Deeper sandy and sandy loam sites showed intermediate declines. Particularly large declines occurred in shallow soil arid sites dominated by shadscale (Atriplex confertifolia) and other saltbush species. Blackbrush (Coleogyne ramosissima), one of the dominant species in the park, showed moderate declines, primarily on shallower soils. No evidence for widespread death in either blackbrush or pinyon-juniper woodlands were noted, although recent severe drought and a weakened Arizona Monsoon since 2018 may be causing impacts to the woodland species. Relationships with livestock grazing are also examined, based on data collected on long-term monitoring plots established between 2008 and 2020. There is evidence that areas with intensive livestock grazing have shown larger declines than ungrazed areas, but these impacts need to be explored more fully at the local allotment and pasture level, and correlated with actual grazing animal unit months (AUM)’s. Several management recommendations are made, including additional plot-based long-term monitoring, exploration of cultural resource inventories and erodible soils, how these observed changes can affect livestock grazing management decisions in the park, and further exploration using NDVI data from 2018 and forward.
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Lawrence, David, Mike Tercek, Amber Runyon e Jeneva Wright. Historical and projected climate change for Grand Canyon National Park and surrounding areas. National Park Service, 2024. http://dx.doi.org/10.36967/2301726.
Testo completoAbstract (sommario):
Globally, anthropogenic climate change is one of the greatest threats to resources in protected areas. This report examines historical and projected climate change across the Greater Grand Canyon Landscape (GGCL), including Grand Canyon National Park. Grand Canyon National Park warmed significantly from 1895-2020 (annual mean increase of 1.89? F/century), with temperatures increasing at a faster rate from 1970-2020 (6.31? F/century). Warming occurred at all elevations and seasons across the GGCL, but rates differed spatially. Average annual total precipitation within Grand Canyon National Park did not change significantly over either period examined (1895-2020; 1970-2020). A variety of changes in the region of Grand Canyon National Park have been detected and attributed, at least in part, to anthropogenic climate change, including reduced soil moisture (and associated drought), reduced Colorado River flow, doubling of the area burned by wildfire across the western United States, reduced regeneration of low-elevation ponderosa pine and Douglas-fir as well as pinyon pine and juniper populations, northward shifts in many bird species distributions and declines of bird species occupancy in the Mojave Desert, and reduced bumble bee species richness and abundance (key pollinators). To help managers understand and plan around a range of plausible future climates, we present two plausible but contrasting climate futures for the Greater Grand Canyon Landscape, characterized at mid-century (2040-2069) and late-century (2070-2099). Examining multiple plausible futures avoids over-optimizing management strategies for a single projected future that may not occur. Overarching patterns that emerged from both climate futures include additional warming (average, as well as extreme temperatures), seasonal increases in extreme precipitation events, fewer freezing days and days with snow, and higher moisture deficit (a correlate with landscape dryness, conditions conducive to fire, and vegetation stress). The selected climate futures differed in terms of 1) the degree of warming, 2) whether winter precipitation increases or decreases, 3) whether annual precipitation increases or stays similar, 4) whether drought conditions increase or decrease, and 5) whether runoff increases or decreases. Runoff is projected to occur earlier under both climate futures and is projected to exhibit a more episodic pattern. Based on a literature review, projected changes to the physical, ecological, and cultural resource domains of the region resulting from anthropogenic climate change include: ? Increasing drought risk and aridification ? Reduced Colorado River flow ? Reduced groundwater infiltration ? Decreasing runoff (from snow or rain) in the spring, summer, and fall, and increasing runoff in the winter ? Increasing occurrence of large fires ? Increasing invasive grasses in the Mojave Desert ecosystems west of the park, providing more fuel for wildfire ? Exacerbated post-fire erosion and sediment in Grand Canyon watersheds ? Increased episodes of drought-induced tree mortality ? Upslope shifts of the elevational zones of pinyon-juniper woodland, ponderosa pine forest, and spruce-fir forest, as well as increases in non-forest areas and aboveground biomass declines ? Reduced abundance of riparian vegetation that tolerates water inundation ? Increasing invasive plant distribution and abundance, favoring their establishment and productivity ? Colonization of the GGCL by some bird species and extirpation of others ? Increasing non-native fish populations relative to native fishes ? Declining butterfly populations ? Increasing temperatures will increase visitation, especially during winter and shoulder seasons ? Exacerbation of existing threats to archeological resources, cultural landscapes, and historic structures, as well as emergent vulnerabilities related to climate change One goal of this work is to support the Resource Stewardship Strategy (RSS) process that Grand Canyon National Park plans to undertake. We anticipate that connecting the climate changes described here to the climate sensitivities of resources within the park will play a critical role in setting goals and strategies during development of the RSS, as well as proactively adapting to anticipated changes.
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Albright, Jeff, Kim Struthers, Lisa Baril e Mark Brunson. Natural resource conditions at Valles Caldera National Preserve: Findings & management considerations for selected resources. National Park Service, giugno 2022. http://dx.doi.org/10.36967/nrr-2293731.
Testo completoAbstract (sommario):
Valles Caldera National Preserve (VALL) encompasses 35,977 ha (88,900 ac) in the Jemez Mountains of north-central New Mexico and is surrounded by the Santa Fe National Forest, the Pueblo of Santa Clara, and Bandelier National Monument. VALL’s explosive volcanic origin, about 1.23 million years ago, formed the Valles Caldera—a broad, 19- to 24-km (12- to 15-mi) wide circular depression. It is one of the world’s best examples of a young caldera (in geologic time) and serves as the model for understanding caldera resurgence worldwide. A series of resurgent eruptions and magmatic intrusive events followed the original explosion, creating numerous volcanic domes in present day VALL—one of which is Redondo Peak at an elevation of 3,430 m (11,254 ft), which is the second highest peak in the Jemez Mountains. In fact, VALL in its entirety is a high-elevation preserve that hosts a rich assemblage of vegetation, wildlife, and volcanic resources. The National Park Service (NPS) Natural Resource Condition Assessment (NRCA) Program selected VALL to pilot its new NRCA project series. VALL managers and the NRCA Program selected seven focal study resources for condition evaluation. To help us understand what is causing change in resource conditions, we selected a subset of drivers and stressors known or suspected of influencing the preserve’s resources. What is causing change in resource conditions? Mean temperatures during the spring and summer months are increasing, but warming is slower at VALL than for neighboring areas (e.g., Bandelier National Monument). The proportion of precipitation received as snow has declined. From 2000 to 2018, forest pests damaged or killed 75% of the preserve’s forested areas. Only small, forested areas in VALL were affected by forest pests after the 2011 Las Conchas and the 2013 Thompson Ridge fires. The all-sky light pollution model and the sound pressure level model predict the lowest degree of impacts from light and sound to be in the western half of the preserve.
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Leis, Sherry, e Mary Short. Vegetation community monitoring at Pea Ridge National Military Park, Arkansas: 2007–2021. National Park Service, giugno 2023. http://dx.doi.org/10.36967/2299454.
Testo completoAbstract (sommario):
Resource managers at Pea Ridge National Military Park manage the natural communities of the park as a backdrop for interpreting the civil war battle that occurred on March 7–8, 1862. Restoration of the landscape to the vegetation communities that were present at the time of the battle is ongoing. Priorities for restoration include density, form, and vegetation structure, but native representative species are also desired. Heartland Inventory and Monitoring Network ecologists observed plant community sites in park woodlands in 2007, 2012, 2016, and 2021. Climate may influence vegetation and other park natural resources. Temperatures have been increasing at the park, but precipitation and drought indices did not demonstrate significant trends. There was a great degree of interannual variability in precipitation and drought metrics. Phenological data indicated earlier first bloom and leaf-out dates. Overstory canopy, basal area, density, and tree stocking were similar through time, but class 1, midstory trees increased in basal area and density after 2007. The overstory structure remained that of a closed woodland despite prescribed fires and cedar thinning that occurred at the park. Our monitoring data show that fire management goals for overstory reduction have not yet been met. Ground cover was similar through time except for bare soil and deciduous leaf litter. Bare soil and leaf litter experienced a pulse in variability in 2012 and 2021, presumably in response to heterogeneous prescribed fires. Maintaining heterogeneous ground cover may best support biodiversity across the landscape. Ground flora cover (excluding tree regeneration) increased by 88% from 2007 to 2021, meeting a fire management goal. However, ground flora cover was heterogeneous across the sites. Concomitant with the increase in ground flora cover, we observed notable increases in alpha diversity (mean site species richness) and gamma diversity (parkwide species richness) across the monitoring period. Although increases may have been related to treatments and environmental factors, we also improved our botanical sampling preparation and included an expert botanist on the crew in 2021. Species composition of the ground flora was assessed via guilds and indicator species. Although tree regeneration was not included in estimates of total ground flora cover, it was highly variable through time. The seedling class comprised the majority of the regeneration stems observed. Although mean small sapling density values increased by 535% over 2007 levels, there was a great deal of variability among the sites, indicating small sapling estimates were contained within the confidence intervals and not truly different through time. Forbs comprised the greatest abundance of the ground flora guilds through time, except in 2012. Forbs also exhibited the greatest variability in all years except for 2012. Woody species increased over our monitoring record but remained low in cover. We analyzed a set of 50 indicator species for Ozark highlands woodlands to understand changes in the ground flora. The number of woodland indicator species observed in each monitoring event was low (ranged from 7–14 species) with the highest number of species observed in 2021. We also calculated invasive species metrics and found the number of invasive species increased from 2 to 11 over the monitoring record. Nepalese browntop (Microstegium vimineum) was the most abundant of these species. Our confidence in the 2021 ground flora observations was high. We found our observer error to be within standard levels, including agreement on species cover estimates. Not all sites have received the number of burns described in the park’s ecological fire management goals. Our monitoring data show that one of the fire management goals, increased ground flora cover, has been met, but the other two goals for overstory density reduction and seedling density have not yet been met. Further analysis of species composition of the overstory and tree regeneration will be needed after the fire treatments have been completed to determine if all fire management goals are being met.
8
Russo, David, e William A. Jury. Characterization of Preferential Flow in Spatially Variable Unsaturated Field Soils. United States Department of Agriculture, ottobre 2001. http://dx.doi.org/10.32747/2001.7580681.bard.
Testo completoAbstract (sommario):
Preferential flow appears to be the rule rather than the exception in field soils and should be considered in the quantitative description of solute transport in the unsaturated zone of heterogeneous formations on the field scale. This study focused on both experimental monitoring and computer simulations to identify important features of preferential flow in the natural environment. The specific objectives of this research were: (1) To conduct dye tracing and multiple tracer experiments on undisturbed field plots to reveal information about the flow velocity, spatial prevalence, and time evolution of a preferential flow event; (2) To conduct numerical experiments to determine (i) whether preferential flow observations are consistent with the Richards flow equation; and (ii) whether volume averaging over a domain experiencing preferential flow is possible; (3) To develop a stochastic or a transfer function model that incorporates preferential flow. Regarding our field work, we succeeded to develop a new method for detecting flow patterns faithfully representing the movement of water flow paths in structured and non-structured soils. The method which is based on application of ammonium carbonate was tested in a laboratory study. Its use to detect preferential flow was also illustrated in a field experiment. It was shown that ammonium carbonate is a more conservative tracer of the water front than the popular Brilliant Blue. In our detailed field experiments we also succeeded to document the occurrence of preferential flow during soil water redistribution following the cessation of precipitation in several structureless field soils. Symptoms of the unstable flow observed included vertical fingers 20 - 60 cm wide, isolated patches, and highly concentrated areas of the tracers in the transmission zone. Soil moisture and tracer measurements revealed that the redistribution flow became fingered following a reversal of matric potential gradient within the wetted area. Regarding our simulation work, we succeeded to develop, implement and test a finite- difference, numerical scheme for solving the equations governing flow and transport in three-dimensional, heterogeneous, bimodal, flow domains with highly contrasting soil materials. Results of our simulations demonstrated that under steady-state flow conditions, the embedded clay lenses (with very low conductivity) in bimodal formations may induce preferential flow, and, consequently, may enhance considerably both the solute spreading and the skewing of the solute breakthrough curves. On the other hand, under transient flow conditions associated with substantial redistribution periods with diminishing water saturation, the effect of the embedded clay lenses on the flow and the transport might diminish substantially. Regarding our stochastic modeling effort, we succeeded to develop a theoretical framework for flow and transport in bimodal, heterogeneous, unsaturated formations, based on a stochastic continuum presentation of the flow and a general Lagrangian description of the transport. Results of our analysis show that, generally, a bimodal distribution of the formation properties, characterized by a relatively complex spatial correlation structure, contributes to the variability in water velocity and, consequently, may considerably enhance solute spreading. This applies especially in formations in which: (i) the correlation length scales and the variances of the soil properties associated with the embedded soil are much larger than those of the background soil; (ii) the contrast between mean properties of the two subdomains is large; (iii) mean water saturation is relatively small; and (iv) the volume fraction of the flow domain occupied by the embedded soil is relatively large.
9
Peralta, Airy, e Chris Ray. Lagomorph ladders: Assessing a multi-host community and potential for spillover of rabbit hemorrhagic disease at Great Sand Dunes National Park and Preserve. National Park Service, 2024. http://dx.doi.org/10.36967/2303667.
Testo completoAbstract (sommario):
Rabbit hemorrhagic disease virus type 2 (RHDV2) has caused dramatic declines in rabbits and hares on several continents, with cascading effects on local ecology. Recent mortalities have been reported for several rabbit and hare species in the United States, suggesting broad susceptibility of lagomorphs. If this susceptibility extends to the American pika (Ochotona princeps), the most cold-adapted lagomorph, it could compound climate-mediated threats to this species. Due to climate change, American pikas are predicted to experience significant upslope range retraction during this century. Using an analogy borrowed from wildfire scenarios, other lagomorph species occurring at lower and mid-elevations could act as ?ladder fuels? to wick RHDV2 into high-elevation pika populations. To address this concern, we investigated spatial patterns of habitat use by pikas and other lagomorphs in Great Sand Dunes National Park and Preserve (GRSA), which borders several counties that have reported RHDV2. In 2022, we surveyed 115 plots from a spatially balanced sample of pika habitats in the park, including 48 legacy plots from a pika survey conducted in 2010-2012. Pika detections at the plot level were paired with topographic and environmental indices to estimate minimum habitat occupancy and determine its covariates. Leporid (rabbit and hare) detections at these same plots were used to model presence using similar covariates and correcting for imperfect detection. Our best-supported models of pika and leporid presence were then used to estimate the probability of contact between these taxa within the park. Our mean estimate of pika habitat occupancy was at least 95% during 2022 in GRSA, slightly higher than in 2010-2012, and effects of elevation and precipitation on pika occupancy were as expected from the previous study. Leporid presence at these same plots was 48% after correcting for imperfect detection. The best model of leporid presence supported a negative effect of elevation, in agreement with other studies of these taxa. The best pika and leporid models also included a positive effect of incoming solar radiation. Finally, we used our best models of pika habitat occupancy and leporid presence within the park to map the potential for areas of contact and RHDV2 transmission between these taxa. Our results indicate some potential for contact within subalpine forests, Specifically in the northern half of the park near the lower reach of the Sand Creek Trail and in the far south just north of California Peak.