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AILI, AISHAJIANG, XU HAILIANG, LIU XINGHONG, ZEESHAN AHMED et LI LI. « Dynamics of dust storm and its response to meteorological conditions and anthropogenic impact in South edge of Taklimakan desert, China ». MAUSAM 72, no 3 (22 octobre 2021) : 619–26. http://dx.doi.org/10.54302/mausam.v72i3.1311.
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In this study, the varying trends of dust storm frequency in a typical oasis located at the South edge of Taklimakan desert, China were analyzed by using time series analysis and regression models. The LUCC (land use/cover change) data, NDVI (Normalized Difference Vegetation Index) remote sensing data, meteorological data and dust storm frequency data for the period of 2004-2018 were collected from local station and ERDAS (Earth Resources Data Analysis System) software, the multivariate relationships between human activities, natural factor and dust storm frequencies were analyzed by using Principal Component Analysis (PCA). Results indicated that the annual dust storm frequency in the study period increased with fluctuation. The monthly dust storm frequency shows higher values between the months of March and June, which accounts for 72.3% of the annual dust storm frequency. Precipitation and wind speed are two meteorological factors which can impact the dust storm formation and its frequency. The correlation between dust storm frequency and temperature was insignificant. Moreover, human activities indirectly affected the dynamics of dust storms by changing the vegetation cover and direct dust emissions. Furthermore, multivariate analysis highlighted a clear relationship among dust storm frequency, meteorological factors and NDVI. The high loadings of dust storm frequency, precipitation, wind speed and NDVI on a PC indicated that increase in precipitation and NDVI will decline dust storm frequency, whereas higher wind speed will enhance dust storm frequency. The findings of this study could be useful to understand the possible causes of dust storms, which can provide the basis for controlling the dust storm source region and also mitigation of the negative effects dust storm on the environment.
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Grabowska, Katarzyna. « Changes in Storm Frequency in the Mediterranean Sea Region ». Miscellanea Geographica 14, no 1 (1 décembre 2010) : 71–78. http://dx.doi.org/10.2478/mgrsd-2010-0007.
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Abstract Storms in the European part of the Mediterranean Sea Basin are characterized in the paper. Data on storm days comes from the years 1986-2008, from fourteen stations located on the coast and on islands of the Mediterranean Sea (Gibraltar, Valencia, Palma de Majorca, Marseille, Ajaccio – Corsica, Cagliari – Sardinia, Palermo – Sicily, Naples, Luqa – Malta, Thessaloniki, Athens, Souda – Crete, Rhodes Airport – Rhodes and Larnaca – Cyprus). The greatest number of storm days was noted in Corsica (870 - on the average 37,8 per year) and the least in Gibraltar (371 – 16,1). In most of the examined stations storms took place most frequently in the fall (from 19 to 46%). The smallest number of storm days was observed in winter (western and central part of the region) and in summer (eastern part). From a year-to-year analysis of storm days, it was found that their trend, at almost at all the stations, is negative. The strongest negative trend was observed in Valencia, Naples and Cagliari (-8,5 days/10 years). A growing trend, reaching 3 storm days/10 years, was only found in Cyprus.
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Luo, Y., Q. Guo, Y. Zheng, K. P. Garmash, L. F. Chernogor et S. N. Shulga. « Geospace storm effects on August 5-6, 2019 ». Kosmìčna nauka ì tehnologìâ 27, no 2 (17 mai 2021) : 45–69. http://dx.doi.org/10.15407/knit2021.02.045.
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Geospace storms are the synergistically interacting magnetic storms, ionospheric storms, atmospheric storms, and the storms in an electric field of magnetospheric, ionospheric, and atmospheric origins. Geospace storms are very diverse, and no two of them behave exactly the same. Therefore, studying the effects of each new storm becomes an urgent task for us. Such research will reveal both the general laws and individual characteristics of storm processes. The purpose of this paper is to present general information about the geospace storm, the results of the analysis of features of magnetic and ionospheric storms. To analyze the magnetic environment, we used the measurement results of magnetic field fluctuations in the range from 1 s to 1000 s, performed at the Magnetometric Observatory of V. N. Karazin Kharkiv National University, and variations of three components of the geomagnetic field, performed at the Low-frequency observatory of the IRA NASU. We analyzed the ionospheric environment using multi-frequency multi-path measurements performed at Harbin Engineering University (China) and also the data of ionosonde. The main results of the work are as follows. An increase in the main parameters of the solar wind on August 5, 2019, led to a geospace storm, which was mainly observed on August 5 and 6, 2019. The main phase of the magnetic storm took place on August 5, 2019, from 06:00 a.m. to 08:30 a.m. The recovery phase lasted at no less than 4 days. The magnetic storm shows significant variations of all components of the geomagnetic field, and there is an increase by order of magnitude of the oscillations’ level of the geomagnetic field in the range from 400 s to 950 s. During the ionospheric storm, significant disturbances occurred in the F region of the ionosphere. The E-region of the ionosphere remained weakly perturbed. The ionospheric storm has severely affected the Doppler spectra of radio waves in the 5 – 10 MHz frequency range. The Doppler spectra are significantly broadened, and the Doppler frequency shift and its quasi-periodic change with a period of 20–40 minutes and a duration of 120–240 minutes have taken place. The quasi-periodic variations of the Doppler frequency shift are due to quasi-periodic variations in the electron concentration, and the amplitude of their relative perturbations varied from 3% to 16%. On one of these paths, the amplitude of the Doppler frequency shift reached 0.7 Hz. And in this case, the amplitude of the relative perturbations of the electron concentration could reach 80 - 90%. In addition, the ionospheric storm little affected the signal amplitude on most radio paths.
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Liu, Yuan, et Daniel B. Wright. « A storm-centered multivariate modeling of extreme precipitation frequency based on atmospheric water balance ». Hydrology and Earth System Sciences 26, no 20 (20 octobre 2022) : 5241–67. http://dx.doi.org/10.5194/hess-26-5241-2022.
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Abstract. Conventional rainfall frequency analysis faces several limitations. These include difficulty incorporating relevant atmospheric variables beyond precipitation and limited ability to depict the frequency of rainfall over large areas that is relevant for flooding. This study proposes a storm-based model of extreme precipitation frequency based on the atmospheric water balance equation. We developed a storm tracking and regional characterization (STARCH) method to identify precipitation systems in space and time from hourly ERA5 precipitation fields over the contiguous United States from 1951 to 2020. Extreme “storm catalogs” were created by selecting annual maximum storms with specific areas and durations over a chosen region. The annual maximum storm precipitation was then modeled via multivariate distributions of atmospheric water balance components using vine copula models. We applied this approach to estimate precipitation average recurrence intervals for storm areas from 5000 to 100 000 km2 and durations from 2 to 72 h in the Mississippi Basin and its five major subbasins. The estimated precipitation distributions show a good fit to the reference data from the original storm catalogs and are close to the estimates from conventional univariate GEV distributions. Our approach explicitly represents the contributions of water balance components in extreme precipitation. Of these, water vapor flux convergence is the main contributor, while precipitable water and a mass residual term can also be important, particularly for short durations and small storm footprints. We also found that ERA5 shows relatively good water balance closure for extreme storms, with a mass residual on average 10 % of precipitation. The approach can incorporate nonstationarities in water balance components and their dependence structures and can benefit from further advancements in reanalysis products and storm tracking techniques.
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Liu, Maofeng, Gabriel A. Vecchi, James A. Smith et Hiroyuki Murakami. « Projection of Landfalling–Tropical Cyclone Rainfall in the Eastern United States under Anthropogenic Warming ». Journal of Climate 31, no 18 (1 août 2018) : 7269–86. http://dx.doi.org/10.1175/jcli-d-17-0747.1.
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Abstract Landfalling–tropical cyclone (TC) rainfall is an important element of inland flood hazards in the eastern United States. The projection of landfalling-TC rainfall under anthropogenic warming provides insight into future flood risks. This study examines the frequency of landfalling TCs and associated rainfall using the GFDL Forecast-Oriented Low Ocean Resolution (FLOR) climate model through comparisons with observed TC track and rainfall over the July–November 1979–2005 seasons. The projection of landfalling-TC frequency and rainfall under the representative concentration pathway (RCP) 4.5 scenario for the late twenty-first century is explored, including an assessment of the impacts of extratropical transition (ET). In most regions of the southeastern United States, competition between increased storm rain rate and decreased storm frequency dominates the change of annual TC rainfall, and rainfall from ET and non-ET storms. In the northeastern United States, a prominent feature is the striking increase of ET-storm frequency but with tropical characteristics (i.e., prior to the ET phase), a key element of increased rainfall. The storm-centered rainfall composite analyses show the greatest increase at a radius of a few hundred kilometers from the storm centers. Over both ocean and land, the increase of rainfall within 500 km from the storm center exceeds the Clausius–Clapeyron scaling for TC-phase storms. Similar results are found in the front-left quadrant of ET-phase storms. Future work involving explorations of multiple models (e.g., higher atmospheric resolution version of the FLOR model) for TC-rainfall projection is expected to add more robustness to projection results.
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Croley II, Thomas E. « Climate-Biased Storm-Frequency Estimation ». Journal of Hydrologic Engineering 6, no 4 (août 2001) : 275–83. http://dx.doi.org/10.1061/(asce)1084-0699(2001)6:4(275).
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Blagoveshchensky, D. V., A. S. Kalishin et M. A. Sergeyeva. « Space weather effects on radio propagation : study of the CEDAR, GEM and ISTP storm events ». Annales Geophysicae 26, no 6 (11 juin 2008) : 1479–90. http://dx.doi.org/10.5194/angeo-26-1479-2008.
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Abstract. The impact of 14 geomagnetic storms from a list of CEDAR, GEM and ISTP storms, that occurred during 1997–1999, on radio propagation conditions has been investigated. The propagation conditions were estimated through variations of the MOF and LOF (the maximum and lowest operation frequencies) on three high-latitude HF radio paths in north-west Russia. Geophysical data of Dst, Bz, AE as well as some riometer data from Sodankyla observatory, Finland, were used for the analysis. It was shown that the storm impact on the ionosphere and radio propagation for each storm has an individual character. Nevertheless, there are common patterns in variation of the propagation parameters for all storms. Thus, the frequency range Δ=MOF−LOF increases several hours before a storm, then it narrows sharply during the storm, and expands again several hours after the end of the storm. This regular behaviour should be useful for the HF radio propagation predictions and frequency management at high latitudes. On the trans-auroral radio path, the time interval when the signal is lost through a storm (tdes) depends on the local time. For the day-time storms an average value tdes is 6 h, but for night storms tdes is only 2 h. The ionization increase in the F2 layer before storm onset is 3.5 h during the day-time and 2.4 h at night. Mechanisms to explain the observed variations are discussed including some novel possibilities involving energy input through the cusp.
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Villarini, Gabriele, Gabriel A. Vecchi, Thomas R. Knutson, Ming Zhao et James A. Smith. « North Atlantic Tropical Storm Frequency Response to Anthropogenic Forcing : Projections and Sources of Uncertainty ». Journal of Climate 24, no 13 (1 juillet 2011) : 3224–38. http://dx.doi.org/10.1175/2011jcli3853.1.
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Abstract The impact of future anthropogenic forcing on the frequency of tropical storms in the North Atlantic basin has been the subject of intensive investigation. However, whether the number of North Atlantic tropical storms will increase or decrease in a warmer climate is still heavily debated and a consensus has yet to be reached. To shed light on this issue, the authors use a recently developed statistical model, in which the frequency of North Atlantic tropical storms is modeled by a conditional Poisson distribution with rate of occurrence parameter that is a function of tropical Atlantic and mean tropical sea surface temperatures (SSTs). It is shown how the disagreement among dynamical modeling projections of late-twenty-first-century tropical storm frequency can be largely explained by differences in large-scale SST patterns from the different climate model projections used in these studies. The results do not support the notion of large (~200%) increases in tropical storm frequency in the North Atlantic basin over the twenty-first century in response to increasing greenhouse gases (GHGs). Because the statistical model is computationally inexpensive, it is used to examine the impact of different climate models and climate change scenarios on the frequency of North Atlantic tropical storms. The authors estimate that the dominant drivers of uncertainty in projections of tropical storm frequency over the twenty-first century are internal climate variations and systematic intermodel differences in the response of SST patterns to increasing GHGs. Relative to them, uncertainties in total GHG emissions or other climate forcings, within the scenarios explored here, represent a minor source of uncertainty in tropical storm frequency projections. These results suggest that reducing uncertainty in future projections of North Atlantic tropical storm frequency may depend as critically on reducing the uncertainty in the sensitivity of tropical Atlantic warming relative to the tropical mean, in response to GHG increase, as on improving dynamical or statistical downscaling techniques. Moreover, the large uncertainties on century-scale trends that are due to internal climate variability are likely to remain irreducible for the foreseeable future. As a further illustration of the statistical model’s utility, the authors model projected changes in U.S. landfalling tropical storm activity under a variety of different climate change scenarios and climate models. These results are similar to those for the overall number of North Atlantic tropical storms, and do not point to a large increase in U.S. landfalling tropical storms over the twenty-first century in response to increasing GHGs.
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Wehner, Michael F., G. Bala, Phillip Duffy, Arthur A. Mirin et Raquel Romano. « Towards Direct Simulation of Future Tropical Cyclone Statistics in a High-Resolution Global Atmospheric Model ». Advances in Meteorology 2010 (2010) : 1–13. http://dx.doi.org/10.1155/2010/915303.
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We present a set of high-resolution global atmospheric general circulation model (AGCM) simulations focusing on the model's ability to represent tropical storms and their statistics. We find that the model produces storms of hurricane strength with realistic dynamical features. We also find that tropical storm statistics are reasonable, both globally and in the north Atlantic, when compared to recent observations. The sensitivity of simulated tropical storm statistics to increases in sea surface temperature (SST) is also investigated, revealing that a credible late 21st century SST increase produced increases in simulated tropical storm numbers and intensities in all ocean basins. While this paper supports previous high-resolution model and theoretical findings that the frequency of very intense storms will increase in a warmer climate, it differs notably from previous medium and high-resolution model studies that show a global reduction in total tropical storm frequency. However, we are quick to point out that this particular model finding remains speculative due to a lack of radiative forcing changes in our time-slice experiments as well as a focus on the Northern hemisphere tropical storm seasons.
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Shamsan, Z. A., M. Alammar, A. Alharthy, A. Aldahmash, K. A. Al-Snaie et A. M. Al-Hetar. « Micrometer and Millimeter Wave P-to-P Links Under Dust Storm Effects in Arid Climates ». Engineering, Technology & ; Applied Science Research 9, no 4 (10 août 2019) : 4520–24. http://dx.doi.org/10.48084/etasr.2972.
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A dust storm is the main attenuation factor that can disturb receiving radio signals in arid climate condition as in Saudi Arabia. This paper presents a study on the effect of dust storms on the received radio frequency power in a homogenous environment in the city of Riyadh. A number of micrometer and millimeter wave links have been considered along with several measured dust storm data to investigate the dust storm effects. The results showed that dust storm can critically influence the communication link and this effect grows up as the physical distance between the transmitter and the receiver increases. The negative effect of the dust storm apparently appears at high-frequency bands allocated for the next communication generation (5G) which imposes finding solutions to mitigate the effects of this phenomenon.
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Yahya, Bashar Muneer, et Dursun Zafer Seker. « The Impact of Dust and Sandstorms in Increasing Drought Areas in Nineveh Province, North-western Iraq ». Journal of Asian and African Studies 54, no 3 (21 novembre 2018) : 346–59. http://dx.doi.org/10.1177/0021909618812913.
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According to many local and international reports, the risk of dust and sandstorms has increased significantly in Iraq, creating serious environmental and social problems. In this study Nineveh province was selected as the study area to investigate the relationship between the increase in such storms and drought expansion. In the study, storm-feeding regions and a probable storm path were detected using remote sensing and Geographic Information System (GIS). Standardized Precipitation Index (SPI) and runoff values were estimated and gathered as supplementary data with rainfall, temperature and storm frequency, where all the data were standardized to make them statistically comparable. Temporal variations analysis and Spearman’s rank correlation techniques were applied to summarize the strength relationships between the storm frequency and the entire dataset. Unusual behaviours were noticed and represented by decreasing runoff values and drought conditions fluctuating between moderate to extreme, where these behaviours were accompanied by an abnormal increase in storm frequency. Reasonable negative relationships equalled - 0.78 for rainfall and - 0.61 for runoff, while positive rank correlations equalled + 0.45 for temperature and + 0.16 for SPI. These results indicate a positive relationship between the storm frequency and increased drought areas, where 2.2% of the territory turned to drought and desert areas during the studied period between 1992 and 2017.
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RAO, Y. R., P. CHITTIBABU, S. K. DUBE, A. D. RAO et P. C. SINHA. « Storm surge prediction and frequency analysis for Andhra coast of India ». MAUSAM 48, no 4 (24 novembre 2021) : 555–66. http://dx.doi.org/10.54302/mausam.v48i4.4322.
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Storm surges associated with severe cyclonic storms are common occurrences along the east coast of India. The coastal districts of Andhra Pradesh have experienced major surges in the past. Storm surges and the rains associated with cyclones are major causes for coastal flooding in this region. An attempt has been made, in this paper, to simulate surges along the Andhra coast that would have occurred due to severe cyclones during 1891-1996. Inland inundation due to surges is also estimated by using an empirical formula. The computed results are validated with the available observations. The comparison using post-storm survey reports, appears reasonably good to assert that the model is capable of predicting the peak surge amplitude and its location. Frequency of occurrence relationships is obtained for various zones along the coastal region for the purpose of risk analysis.
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Luo, Yiyang, Leonid Chernogor, Kostiantyn Garmash, Qiang Guo, Victor Rozumenko et Yu Zheng. « Dynamic processes in the magnetic field and in the ionosphere during the 30 August–2 September 2019 geospace storm : influence on high frequency radio wave characteristics ». Annales Geophysicae 39, no 4 (15 juillet 2021) : 657–85. http://dx.doi.org/10.5194/angeo-39-657-2021.
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Abstract. The concept that geospace storms are comprised of synergistically coupled magnetic storms, ionospheric storms, atmospheric storms, and storms in the electric field originating in the magnetosphere, the ionosphere, and the atmosphere (i.e., electrical storms) was validated a few decades ago. Geospace storm studies require the employment of multiple-method approaches to the Sun–interplanetary medium–magnetosphere–ionosphere–atmosphere–Earth system. This study provides general analysis of the 30 August–2 September 2019 geospace storm, the analysis of disturbances in the geomagnetic field and in the ionosphere, as well as the influence of the ionospheric storm on the characteristics of high frequency (HF) radio waves over the People's Republic of China. The main results of the study are as follows. The energy and power of the geospace storm have been estimated to be 1.5×1015 J and 1.5×1010 W, and thus, this storm is weak. The energy and power of the magnetic storm have been estimated to be 1.5×1015 J and 9×109 W, i.e., this storm is moderate, and a characteristic feature of this storm is the duration of the main phase of up to 2 d. The recovery phase also was lengthy and was no less than 2 d. On 31 August and 1 September 2019, the variations in the H and D components attained 60–70 nT, while the Z-component variations did not exceed 20 nT. On 31 August and 1 September 2019, the level of fluctuations in the geomagnetic field in the 100–1000 s period range increased from 0.2–0.3 to 2–4 nT, while the energy of the oscillations showed a maximum in the 300–400 to 700–900 s period range. During the geospace storm, a moderately to strongly negative ionospheric storm manifested itself by the reduction in the ionospheric F-region electron density by a factor of 1.4 to 2.4 times on 31 August and 1 September 2019, compared to the its values on the reference day. Appreciable disturbances were also observed to occur in the ionospheric E region and possibly in the Es layer. In the course of the ionospheric storm, the altitude of reflection of radio waves could sharply increase from ∼150 to ∼300–310 km. The atmospheric gravity waves generated within the geospace storm modulated the ionospheric electron density; for the ∼30 min period oscillation, the amplitude of the electron density disturbances could attain ∼40 %, while it did not exceed 6 % for the ∼15 min period. At the same time, the height of reflection of the radio waves varied quasi-periodically with a 20–30 km amplitude. The results obtained have made a contribution to the understanding of the geospace storm physics, to developing theoretical and empirical models of geospace storms, to the acquisition of detailed understanding of the adverse effects that geospace storms have on radio wave propagation, and to applying that knowledge to effective forecasting of these adverse influences.
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Золотухина, Нина, Nina Zolotukhina, Владимир Куркин, Vladimir Kurkin, Неля Полех et Nelya Polekh. « Ionospheric disturbances over East Asia during intense December magnetic storms of 2006 and 2015 : similarities and differences ». Solar-Terrestrial Physics 4, no 3 (28 septembre 2018) : 28–42. http://dx.doi.org/10.12737/stp-43201805.
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Using data from ionosondes, located in East Asia, and total electron content maps, we have made a comparative analysis of ionospheric disturbances associated with the intense geomagnetic storms of December 14–16, 2006 and December 19–22, 2015. These storms had almost equal peak intensities (Dstmin=–162 and –155 nT), but different durations of the main phases (2.5 and 19 hr). At the beginning of both the storms, the region under study was located in the vicinity of the midnight meridian. Ionospheric responses to magnetic storms differed in: i) an increase in the F2-layer critical frequency at subauroral latitudes, caused by an increase in auroral precipitation, during the initial phase of the former storm and the absence of this effect in the latter; (ii) a sharp drop in the critical frequency in the evening hours of the main phase of the latter storm, caused by a shift of the main ionospheric trough to lower latitudes, and the absence of this effect during the former storm; (iii) generation of a short-term positive disturbance observed at subauroral latitudes only in the early recovery phase of the former storm after the negative ionospheric disturbance. During both the storms at middle latitudes there were positive disturbances and wave-like fluctuations of the critical frequency which increased in the vicinity of the dawn meridian. The main causes of the differences between the ionospheric storms are shown to be the differences between the initial conditions of the magnetosphere–ionosphere system and durations of the main phases of magnetic storms.
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Yang, Ji, Kun Zhao, Xingchao Chen, Anning Huang, Yuanyuan Zheng et Kangyuan Sun. « Subseasonal and Diurnal Variability in Lightning and Storm Activity over the Yangtze River Delta, China, during Mei-yu Season ». Journal of Climate 33, no 12 (15 juin 2020) : 5013–33. http://dx.doi.org/10.1175/jcli-d-19-0453.1.
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AbstractUsing 5 years of operational Doppler radar, cloud-to-ground (CG) lightning observations, and National Centers for Environmental Prediction reanalysis data, this study examined the spatial and temporal characteristics of and correlations between summer storm and lightning activity over the Yangtze River Delta (YRD), with a focus on subseasonal variability and diurnal cycles. The spatiotemporal features of storm top, duration, maximum reflectivity, size, and cell-based vertical integrated liquid water were investigated using the Storm Cell Identification and Tracking algorithm. Our results revealed that there was high storm activity over the YRD, with weak diurnal variations during the mei-yu period. Specifically, storms were strongly associated with mei-yu fronts and exhibited a moderate size, duration, and intensity. On average, afternoon storms exhibited stronger reflectivity and higher storm tops than morning storms, as evidenced by the afternoon peak in CG lightning. The storm intensity strengthened in the post-mei-yu period, due to an increase in atmospheric instability; this was accompanied by a higher frequency of CG lighting. The diurnal cycles of storm frequency and CG lightning in the post-mei-yu period followed a unimodal pattern with an afternoon peak. This is attributable to increased thermodynamic instability in the afternoon, as little diurnal variation was observed for wind shear and moisture. An inverse correlation between lightning occurrence and mean peak current (MPC) for negative CG lightning was evident during the pre-mei-yu and mei-yu periods. The diurnal variation in MPC for negative CG lightning agreed well with that for storm intensity.
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Бадин, Владимир, et Vladimir Badin. « Resonant ULF absorption in storm time conditions ». Solar-Terrestrial Physics 3, no 1 (5 mai 2017) : 103–13. http://dx.doi.org/10.12737/article_58f97156b06fa5.51468016.
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The work deals with ULF radar observations of the high-latitude ionosphere. Doppler data from the Norwegian STARE instrument are analyzed for the moderate magnetic storm observed on December 31, 1999–January 01, 2000. Upon averaging the Doppler signals along radar beams, the spectral power of signals is determined for each beam as a function of frequency ranging from 1 to 10 mHz. Sharp drops (about 10 dB) of spectral powers with frequency are found for all radar beams. A variational analysis of spectral powers is carried out by least squares, with power drops being modeled by stepwise profiles constructed of mean spectral powers preceding and succeeding the drops. Using this variational analysis, the frequency of the power drop is determined for each radar beam. Being averaged over all beams, this frequency is 4.8 ± 0.5 mHz. The results obtained are interpreted as resonant absorption of ultra-low-frequency (ULF) waves occurring on eigenfrequencies of magnetic field lines over wave propagation from the magnetopause deep into the magnetosphere.
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Watt, W. E., K. C. A. Chow, W. D. Hogg et K. W. Lathem. « A 1-h urban design storm for Canada ». Canadian Journal of Civil Engineering 13, no 3 (1 juin 1986) : 293–300. http://dx.doi.org/10.1139/l86-041.
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The advent of stormwater modelling techniques has resulted in the need for a Canadian urban design storm. As a first stage in meeting this need, a 1-h urban design storm has been developed. This design storm, which is fully described by two parameters and the rainfall depth as given by Atmospheric Environment Service (AES) intensity–duration–frequency data, is specified for a wide range of return periods for all regions of Canada. Extensive comparisons with observed 1-h storms, both in the temporal domain and the frequency domain, indicate that the two-parameter mathematical model is capable of simulating individual rainfall events and an average or 'design' event for any particular site. The design storm model has been extended on a regional basis by evaluating the two parameters for each of 45 AES stations across Canada. Regional values of the parameters have been derived so that a design storm can be determined for an area without rainfall records. Key words: design storm, urban drainage, storm water, rainfall, temporal distribution, regional analysis.
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Babcock, Jeffrey M., Barry A. Kirkendall et John A. Orcutt. « Relationships between ocean bottom noise and the environment ». Bulletin of the Seismological Society of America 84, no 6 (1 décembre 1994) : 1991–2007. http://dx.doi.org/10.1785/bssa0840061991.
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Abstract Observations of ocean bottom low-frequency noise and surface environmental data over a period of 27 days in the northern Atlantic during the SAMSON and SWADE experiments reveal how closely related the noise is to meteorological conditions. Double-frequency microseisms produced by nonlinear interactions of storm-induced surface gravity waves are especially evident in the frequency band 0.16 to 0.3 Hz and show a high variability in both amplitude and peak frequencies. Bifurcated at times, the peak that characterizes the microseism band contains local and distant or “teleseismic” components, which are generated at different locations. Weather and storm fetch appear to be the major contributions to the size and shape of microseism spectra. Storm development on the sea surface is associated with progressively lower microseism frequencies along with a concurrent increase in amplitude. The single-frequency microseism peak is a continuous feature and is observed to portray the same time-dependent spectral characteristics as the portion of the double-frequency peak associated with distant storms. Coherence studies confirm that both peaks (single and teleseismic double) originate at a distant source. These peaks are generated at roughly the same location with some storm component over the coastline.
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Weisse, Ralf, Hans von Storch et Frauke Feser. « Northeast Atlantic and North Sea Storminess as Simulated by a Regional Climate Model during 1958–2001 and Comparison with Observations ». Journal of Climate 18, no 3 (1 février 2005) : 465–79. http://dx.doi.org/10.1175/jcli-3281.1.
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Abstract An analysis of the storm climate of the northeast Atlantic and the North Sea as simulated by a regional climate model for the past 44 yr is presented. The model simulates the period 1958–2001 driven by the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis. Comparison with observations shows that the model is capable of reproducing impact-related storm indices such as the number of severe and moderate storms per year or the total number of storms and upper intra-annual percentiles of near-surface wind speed. The indices describe both the year-to-year variability of the frequency, as well as changes in the average intensity of storm events. Analysis of these indices reveals that the average number of storms per year has increased near the exit of the North Atlantic storm track and over the southern North Sea since the beginning of the simulation period (1958), but the increase has attenuated later over the North Sea and the average number of storms per year has been decreasing over the northeast Atlantic since about 1990–95. The frequency of the most severe storms follows a similar pattern over the northeast North Atlantic while too few severe storms occurred in other areas of the model domain, preventing a statistical analysis for these areas.
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KANE, R. P. « Spectral characteristics of Atlantic seasonal storm frequency ». MAUSAM 57, no 4 (26 novembre 2021) : 597–608. http://dx.doi.org/10.54302/mausam.v57i4.499.
Texte intégralRésumé :
lkj & o"kZ 1900&2000 dh vof/k esa vVykafVd egklkxj dh rwQkuh xfrfof/k ¼ftUgas rwQku] izpaM rwQku] vkfn uke fn, x, gaS½ ds fofHkUu lwpdkadksa ds dky Jsf.k;ksa dk vuqØe fo’ys"k.k ,e-b-,e-¼vf/kdre ,uVªkWih fof/k½ }kjk rFkk mldh vkofrZrk ds vk;ke ,e- vkj- ,- ¼cgqq lekJ;.k fo’ys"k.k½ }kjk izkIr fd, x, gaSA fiNys dqN o"kksZa ds vkadM+ksa ¼o"kZ 1950 ls vkxss½ ds vuqlkj budh egRoiw.kZ vkofrZrk,¡ n’kd lfgr( f}okf"kZd dYi] f=okf"kZd dYi {ks=ksa rFkk buls mPp {ks=ksa esa Hkh jghA 2-40 o"kkasZ esa 50 feyhckj ds fuEu v{kka’k {ks=h; iou vkSj 2-40 ,oa 2-85 o"kkasZ ds b- ,u- ,l- vks- ¼,y uhuks/nf{k.kh nksyu½ ?kVuk ds ln`’k f}o"khZ dYi nksyu {ks= esa ¼3&4 o"kkasZ½ rwQku lwpdkad 2-40 rFkk 2-85 o"kksZa ds djhc pje ij jgsA mPp vkofrZrk okys {ks=ksa esa rwQku lwpdkad 4-5&5-5-] 8&9] 11&12 rFkk 14&15 o"kkasZ esa pje ij jgs tcfd b- ,u- ,l- vks- 7-4 ,oa 12&14 o"kksZa esa pje ij jgsA cgq n’kdh; Js.kh esa 28&34]40]50&53]61&63]~70 ,oa ~80 o"kksZa esa ¼ijUrq fHkUu lwpdkadksa ds fy, fHkUu&fHkUu½ rwQku pje ij jgs tks LFky ,oa leqnzh lrg ds rkiekuksa ds leku pje ekuksa ds vuq:Ik jgsA dqy lwpdkadksa esa 90 o"kkZsa esa yxHkx 50 izfr’kr dh m/oZ izo`fr jghA
The time series of the various indices of Atlantic storm activity (number of named storms, hurricanes, etc.) for 1900-2000 were subjected to spectral analysis by MEM (Maximum Entropy Method) and amplitudes of the periodicities were obtained by MRA (Multiple Regression Analysis). For recent data (1950 onwards), significant periodicities were in the quasi-biennial, quasi-triennial regions and also in higher regions, including decadal. In the QBO region (2-3 years), storm indices had peaks near 2.40 and 2.85 years, similar to 2.40 years of 50 hPa low latitude zonal wind and 2.40 and 2.85 years of ENSO (El Niño/Southern Oscillation) phenomenon. In the QTO region (3-4 years), storm indices and ENSO had common peaks near 3.5 years. In higher periodicity regions, storm indices had peaks at 4.5-5.5, 8-9, 11-12 and 14-15 years, while ENSO had peaks at 7.4 and 12-14 years. In the multi-decadal range, storm peaks were at 28-34, 40, 50-53, 61-63, ~70 and ~80 years (but different for different indices), which matched with similar peaks in land and sea surface temperatures. Some indices had large uptrends, ~50% in 90 years.
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Jun, Changhyun, Xiaosheng Qin, Yeou-Koung Tung et Carlo De Michele. « Storm event-based frequency analysis method ». Hydrology Research 49, no 3 (9 novembre 2017) : 700–710. http://dx.doi.org/10.2166/nh.2017.175.
Texte intégralRésumé :
Abstract In this study, a storm event-based frequency analysis method was proposed to mitigate the limitations of conventional rainfall depth–duration–frequency (DDF) analysis. The proposed method takes the number, rainfall depth, and duration of rainstorm events into consideration and is advantageous in estimation of more realistic rainfall quantiles for a given return period. For the purpose of hydraulics design, the rainfall depth thresholds are incorporated to retrieve the rainstorm events for estimating design rainfalls. The proposed method was tested against the observed rainfall data from 1961 to 2010 at Seoul, Korea and the computed rainfall quantiles were compared with those estimated using the conventional frequency analysis method. The study results indicated that the conventional method was likely to overestimate the rainfall quantiles for short rainfall durations. It represented that the conventional method could reflect rainfall characteristics of actual rainstorm events if longer durations (like 24 hours) were considered for estimation of design rainfalls.
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Weiss, Jérôme, Pietro Bernardara et Michel Benoit. « ASSESSMENT OF THE REGIONAL FREQUENCY ANALYSIS TO THE ESTIMATION OF EXTREME STORM SURGES ». Coastal Engineering Proceedings 1, no 33 (11 octobre 2012) : 27. http://dx.doi.org/10.9753/icce.v33.management.27.
Texte intégralRésumé :
Regional frequency analysis (RFA) is performed to estimate extreme storm surges along the French coasts of the Atlantic Ocean, the English Channel and the Southern part of the North Sea. An insight on the formation of physically homogeneous regions from a criterion of propagation of storms is provided. The treatment of the pairwise dependence structure within a given region through a spatial extreme value copula is also considered, leading to a model coupling physically-based RFA and spatial dependence to describe the probabilistic behavior of extreme storm surges.
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Xue, Junchen, Sreeja Vadakke Veettil, Marcio Aquino, Xiaogong Hu, Lin Quan, Dun Liu, Peng Guo et Mengjie Wu. « Performance of BDS B1 Frequency Standard Point Positioning during the Main Phase of Different Classified Geomagnetic Storms in China and the Surrounding Area ». Remote Sensing 14, no 5 (3 mars 2022) : 1240. http://dx.doi.org/10.3390/rs14051240.
Texte intégralRésumé :
Geomagnetic storms are one of the space weather events. The radio signals transmitted by modern navigation systems suffer from the effects of magnetic storms, which can degrade the performance of the whole system. In this study, the performance of the BeiDou Navigation Satellite System (BDS) B1 frequency standard point positioning (SPP) in China and the surrounding area during different classes of storm was investigated for the first time. The statistical analysis of the results revealed that the accuracy of the BDS-2 B1 frequency SPP deteriorated during the storms. The probability of the extrema of the positioning error statistics was largest during strong storms, followed by moderate and weak storms. The positioning accuracy for storms of a similar class was found not to be at the same level. The root mean square error in positioning for the different classes of storm could be at least tens of centimeters in the east, north and up directions. The findings in this study could contribute toward the error constraint of BDS positioning accuracy during different classes of geomagnetic storm and be beneficial to other systems, such as BDS-3, as well.
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Tang, Xu, Jia, Luo et Shao. « Estimating Errors in Sizing LID Device and Overflow Prediction Using the Intensity-Duration-Frequency Method ». Water 11, no 9 (5 septembre 2019) : 1853. http://dx.doi.org/10.3390/w11091853.
Texte intégralRésumé :
Low impact development (LID) devices or green infrastructures have been advocated for urban stormwater management worldwide. Currently, the design and evaluation of LID devices adopt the Intensity-Duration-Frequency (IDF) method, which employs the average rainfall intensity. However, due to variations of rainfall intensity during a storm event, using average rainfall intensity may generate certain errors when designing a LID device. This paper presents an analytical study to calculate the magnitude of such errors with respect to LID device design and associated device performance evaluation. The normal distribution rainfall (NDR) with different standard deviations was employed to represent realistic rainfall processes. Compared with NDR method, the error in sizing the LID device was determined using the IDF method. Moreover, the overflow difference calculated using the IDF method was evaluated. We employed a programmed hydrological model to simulate different design scenarios. Using storm data from 31 regions with different climatic conditions in continental China, the results showed that different rainfall distributions (as represented by standard deviations (σ) of 5, 3, and 2) have little influence on the design depth of LID devices in most regions. The relative difference in design depth using IDF method was less than 1.00% in humid areas, −0.61% to 3.97% in semi-humid areas, and the significant error was 46.13% in arid areas. The maximum absolute difference in design depth resulting from the IDF method was 2.8 cm. For a LID device designed for storms with a 2-year recurrence interval, when meeting for the 5-year storm, the relative differences in calculated overflow volume using IDF method ranged from 19.8% to 95.3%, while those for the 20-year storm ranged from 7.4% to 40.5%. The average relative difference of the estimated overflow volume was 29.9% under a 5-year storm, and 12.0% under a 20-year storm. The relative difference in calculated overflow volumes using IDF method showed a decreasing tendency from northwest to southeast. Findings from this study suggest that the existing IDF method is adequate for use in sizing LID devices when the design storm is not usually very intense. However, accurate rainfall process data are required to estimate the overflow volume under large storms.
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Thompson, Philip R., Gary T. Mitchum, Cedric Vonesch et Jianke Li. « Variability of Winter Storminess in the Eastern United States during the Twentieth Century from Tide Gauges ». Journal of Climate 26, no 23 (décembre 2013) : 9713–26. http://dx.doi.org/10.1175/jcli-d-12-00561.1.
Texte intégralRésumé :
Interannual to multidecadal variability of winter storminess in the eastern United States was studied using water level measurements from coastal tide gauges. The proximity to the coast of the primary winter storm track in the region allows the use of tide gauges to study temporal modulations in the frequency of these storms. Storms were identified in high-passed, detided sea level anomalies in 20 gauges from all coasts of North America to assess variability in winter storminess along particular storm tracks. The primary result is a significant multidecadal increase in the number of storms affecting the southeastern United States from the early to late twentieth century. The authors propose that this change is due to an increased tendency for the jet stream to meander south over the eastern United States since the 1950s. This mechanism is supported by long-term changes in the large-scale sea level pressure pattern over North America. The nature of the multidecadal change in storm frequency is unclear, because limited tide gauge record lengths prevent distinguishing between a trend and an oscillation.
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Albugami, Sarah, Steven Palmer, Jonathan Cinnamon et Jeroen Meersmans. « Spatial and Temporal Variations in the Incidence of Dust Storms in Saudi Arabia Revealed from In Situ Observations ». Geosciences 9, no 4 (8 avril 2019) : 162. http://dx.doi.org/10.3390/geosciences9040162.
Texte intégralRésumé :
Monthly meteorological data from 27 observation stations provided by the Presidency of Meteorology and Environment (PME) of Saudi Arabia were used to analyze the spatial and temporal distribution of atmospheric dust in Saudi Arabia between 2000 and 2016. These data were used to analyze the effects of environmental forcing on the occurrence of dust storms across Saudi Arabia by considering the relationships between dust storm frequency and temperature, precipitation, and wind variables. We reveal a clear seasonality in the reported incidence of dust storms, with the highest frequency of events during the spring. Our results show significant positive relationships (p < 0.005) between dust storm occurrence and wind speed, wind direction, and precipitation. However, we did not detect a significant relationship with temperature. Our results reveal important spatial patterns, as well as seasonal and inter-annual variations, in the occurrence of dust storms in Saudi Arabia. For instance, the eastern part of the study area experienced an increase in dust storm events over time, especially in the region near Al-Ahsa. Similarly, an increasing trend in dust storms was also observed in the west of the study area near Jeddah. However, the occurrence of dust storm events is decreasing over time in the north, in areas such as Hail and Qaisumah. Overall, the eastern part of Saudi Arabia experiences the highest number of dust storms per year (i.e., 10 to 60 events), followed by the northern region, with the south and the west having fewer dust storm events (i.e., five to 15 events per year). In addition, our results showed that the wind speeds during a dust storm are 15–20 m/s and above, while, on a non-dust day, the wind speeds are approximately 10–15 m/s or lower. Findings of this study provide insight into the relationship between environmental conditions and dust storm occurrence across Saudi Arabia, and a basis for future research into the drivers behind these observed spatio-temporal trends.
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Middleton, Nick. « Variability and Trends in Dust Storm Frequency on Decadal Timescales : Climatic Drivers and Human Impacts ». Geosciences 9, no 6 (12 juin 2019) : 261. http://dx.doi.org/10.3390/geosciences9060261.
Texte intégralRésumé :
Dust storms present numerous hazards to human society and are particularly significant to people living in the Dust Belt which stretches from the Sahara across the Middle East to northeast Asia. This paper presents a review of dust storm variability and trends in frequency on decadal timescales from three Dust Belt settlements with long-term (>50 years) meteorological records: Nouakchott, Mauritania; Zabol, Iran, and Minqin, China. The inhabitants of each of these settlements have experienced a decline in dust storms in recent decades, since the late 1980s at Nouakchott, since 2004 at Zabol, and since the late 1970s at Minqin. The roles of climatic variables and human activities are assessed in each case, as drivers of periods of high dust storm frequency and subsequent declines in dust emissions. Both climatic and human variables have been important but overall the balance of research conclusions indicates natural processes (precipitation totals, wind strength) have had greater impact than human action, in the latter case both in the form of mismanagement (abandoned farmland, water management schemes) and attempts to reduce wind erosion (afforestation projects). Understanding the drivers of change in dust storm dynamics at the local scale is increasingly important for efforts to mitigate dust storm hazards as climate change projections suggest that the global dryland area is likely to expand in the twenty-first century, along with an associated increase in the risk of drought and dust emissions.
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Rangari, Vinay Ashok, et Sriramoju Sai Prashanth. « Simulation of Urban Drainage System Using a Storm Water Management Model (SWMM) ». Asian Journal of Engineering and Applied Technology 7, no 1 (5 mars 2018) : 7–10. http://dx.doi.org/10.51983/ajeat-2018.7.1.872.
Texte intégralRésumé :
Urban floods are caused due to increase in population density, development of urban infrastructure without paying due consideration to drainage aspects and increase in paved surfaces. Storm water modelling plays an important role in checking issues such as flash floods and urban water-quality problems. The SWMM (Storm Water Management Model) has been an effective tool for simulating floods in urban areas. In this study a SWMM model is developed to analyze drainage network for the campus of National Institute of Technology, Warangal in the city of Warangal, Telangana, India. The model is simulated for one real storm event and 2-year return period of interval 1-hour design storm intensity. Frequency analysis is performed using best fitted distribution i.e., Gumbel’s distribution for different return periods and the frequency values are used for development of IDF (intensity-duration-frequency) curves. Design storm intensity derived from IDF curves for different return periods is used to estimate peak runoff from each sub catchment which is used as input parameter in simulation of runoff in SWMM. GIS methodology is employed for handling spatial data simultaneously. From results, it is observed that some part of campus are commonly affected with flooding, when analysis is performed for two design storms and one day continuous rainfall/precipitation values.
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Rudlosky, Scott D., et Henry E. Fuelberg. « Documenting Storm Severity in the Mid-Atlantic Region Using Lightning and Radar Information ». Monthly Weather Review 141, no 9 (28 août 2013) : 3186–202. http://dx.doi.org/10.1175/mwr-d-12-00287.1.
Texte intégralRésumé :
Abstract Storm severity in the mid-Atlantic region of the United States is examined using lightning, radar, and model-derived information. Automated Warning Decision Support System (WDSS) procedures are developed to create grids of lightning and radar parameters, cluster individual storm features, and data mine the lightning and radar attributes of 1252 severe and nonsevere storms. The study first examines the influence of serial correlation and uses autocorrelation functions to document the persistence of lightning and radar parameters. Decorrelation times are found to vary by parameter, storm severity, and mathematical operator, but the great majority are between three and six lags, suggesting that consecutive 2-min storm samples (following a storm) are effectively independent after only 6–12 min. The study next describes the distribution of lightning jumps in severe and nonsevere storms, differences between various types of severe storms (e.g., severe wind only), and relationships between lightning and radar parameters. The 2σ lightning jump algorithm (with a 10 flashes min−1 activation threshold) yields 0.92 jumps h−1 for nonsevere storms and 1.44 jumps h−1 in severe storms. Applying a 10-mm maximum expected size of hail (MESH) threshold to the 2σ lightning jump algorithm reduces the frequency of lightning jumps in nonsevere storms to 0.61 jumps h−1. Although radar-derived parameters are comparable between storms that produce severe wind plus hail and those that produce tornadoes, tornadic storms exhibit much greater intracloud (IC) and cloud-to-ground (CG) flash rates. Correlations further illustrate that lightning data provide complementary storm-scale information to radar-derived measures of storm intensity.
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Золотухина, Нина, Nina Zolotukhina, Владимир Куркин, Vladimir Kurkin, Неля Полех et Nelya Polekh. « Ionospheric disturbances over East Asia during intense December magnetic storms of 2006 and 2015 : similarities and differences ». Solnechno-Zemnaya Fizika 4, no 3 (28 septembre 2018) : 39–56. http://dx.doi.org/10.12737/szf-43201805.
Texte intégralRésumé :
Using data from ionosondes, located in East Asia, and total electron content maps, we have made a comparative analysis of ionospheric disturbances as-sociated with the intense geomagnetic storms of De-cember 14–16, 2006 and December 19–22, 2015. These storms had almost equal peak intensities (Dstmin=–162 and –155 nT), but different durations of the main phases (2.5 and 19 hr). At the beginning of both the storms, the region under study was located in the vicinity of the midnight meridian. Ionospheric re-sponses to magnetic storms differed in: i) an increase in the F2-layer critical frequency at subauroral latitudes, caused by an increase in auroral precipitation, during the initial phase of the former storm and the absence of this effect in the latter; (ii) a sharp drop in the critical frequency in the evening hours of the main phase of the latter storm, caused by a shift of the main ionospheric trough to lower latitudes, and the absence of this effect during the former storm; (iii) generation of a short-term positive disturbance observed at subauroral latitudes only in the early recovery phase of the former storm after the negative ionospheric disturbance. During both the storms at middle latitudes there were positive dis-turbances and wave-like fluctuations of the critical fre-quency which increased in the vicinity of the dawn me-ridian. The main causes of the differences between the ionospheric storms are shown to be the differences be-tween the initial conditions of the magnetosphere-ionosphere system and durations of the main phases of magnetic storms.
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Zhao, Ming, et Isaac M. Held. « TC-Permitting GCM Simulations of Hurricane Frequency Response to Sea Surface Temperature Anomalies Projected for the Late-Twenty-First Century ». Journal of Climate 25, no 8 (10 avril 2012) : 2995–3009. http://dx.doi.org/10.1175/jcli-d-11-00313.1.
Texte intégralRésumé :
Abstract A tropical cyclone–permitting global atmospheric model is used to explore the hurricane frequency response to sea surface temperature (SST) anomalies generated by coupled models for the late-twenty-first century. Results are presented for SST anomalies averaged over 18 models as well as from 8 individual models. For each basin, there exists large intermodel spread in the magnitude and even the sign of the frequency response among the different SST projections. These sizable variations in response are explored to understand features of SST distributions that are important for the basin-wide hurricane responses. In the North Atlantic, the eastern Pacific, and the southern Indian basins, most (72%–86%) of the intermodel variance in storm frequency response can be explained by a simple relative SST index defined as a basin’s storm development region SST minus the tropical mean SST. The explained variance is significantly lower in the South Pacific (48%) and much lower in the western Pacific basin (27%). Several atmospheric parameters are utilized to probe changes in tropical atmospheric circulation and thermodynamical properties relevant to storm genesis in the model. While all present strong correlation to storm response in some basins, a parameter-measuring tropospheric convective mass flux stands out as skillful in explaining the simulated differences for all basins. Globally, in addition to a modest reduction of total storm frequency, the simulations exhibit a small, but robust eastward and poleward migration of genesis frequency in both the North Pacific and the North Atlantic Oceans. This eastward migration of storms can also be explained by changes in convection.
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Kumar, Edwin A., et Sushil Kumar. « Geomagnetic Storm Effect on F2-Region Ionosphere during 2012 at Low- and Mid-Latitude-Latitude Stations in the Southern Hemisphere ». Atmosphere 13, no 3 (15 mars 2022) : 480. http://dx.doi.org/10.3390/atmos13030480.
Texte intégralRésumé :
The ionospheric effects of six intense geomagnetic storms with Dst index ≤ −100 nT that occurred in 2012 were studied at a low-latitude station, Darwin (Geomagnetic coordinates, 21.96° S, 202.84° E), a low-mid-latitude station, Townsville (28.95° S, 220.72° E), and a mid-latitude station, Canberra (45.65° S, 226.30° E), in the Australian Region, by analyzing the storm–time variations in the critical frequency of the F2-region (foF2). Out of six storms, a storm of 23–24 April did not produce any ionospheric effect. The storms of 30 September–3 October (minimum Dst = −122 nT) and 7–10 October (minimum Dst = −109 nT) are presented as case studies and the same analysis was done for the other four storms. The storm of 30 September–3 October, during its main phase, produced a positive ionospheric storm at all three stations with a maximum percentage increase in foF2 (∆foF2%) of 45.3% at Canberra whereas during the recovery phase it produced a negative ionospheric storm at all three stations with a maximum ∆foF2% of −63.5% at Canberra associated with a decrease in virtual height of the F-layer (h’F). The storm of 7–10 October produced a strong long-duration negative ionospheric storm associated with an increase in h’F during its recovery phase at all three stations with a maximum ∆foF2% of −65.1% at Townsville. The negative ionospheric storms with comparatively longer duration were more pronounced in comparison to positive storms and occurred only during the recovery phase of storms. The storm main phase showed positive ionospheric storms for two storms (14–15 July and 30 September–3 October) and other three storms did not produce any ionospheric storm at the low-latitude station indicating prompt penetrating electric fields (PPEFs) associated with these storms did not propagate to the low latitude. The positive ionospheric storms during the main phase are accounted to PPEFs affecting ionospheric equatorial E × B drifts and traveling ionospheric disturbances due to joule heating at the high latitudes. The ionospheric effects during the recovery phase are accounted to the disturbance dynamo electric fields and overshielding electric field affecting E × B drifts and the storm-induced circulation from high latitudes toward low latitudes leading to changes in the natural gas composition [O/N2] ratio.
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Jimme, M. A., A. L. Disa et M. B. Ngamdu. « Human Perception on the Effects of Dust Storm on the Health of Residents’ of Damaturu Metropolis, Yobe State ». Nigerian Journal of Environmental Sciences and Technology 4, no 2 (octobre 2020) : 421–31. http://dx.doi.org/10.36263/nijest.2020.02.0129.
Texte intégralRésumé :
Dust storms are among nature’s most violent and unpredictable phenomena. High winds lift dirt or sand particles into the air, unleashing a turbulent, suffocating cloud that reduces visibility to almost nothing in a matter of seconds and cause property damage, injuries, and deaths. Damaturu Metropolis has been experiencing dust storm most frequently more especially during the onset of the rainy season. The study examined the human perception on the effects of dust storm on the health of residents’ of Damaturu metropolis with the aim of identifying and examining the causes, frequency, effects of dust storm on human health and socio-economic life of resident and their coping strategies. A total of one hundred (100) copies of interview schedules were administered to residents of Damaturu metropolis. The result indicated that desertification and deforestation are the main cause of dust storm and the frequency of its occurrence is more often and it occurs most frequently in the second quarter of the year at the onset of the rainy season. Its duration of occurrence ranges from thirty minutes to an hour, although sometimes it varies. The identified health effects associated with dust storms include asthma, allergic reaction, injury and Road Traffic Accident (R.T.A). The socio-economic and livelihood of the community is equally affected during the dust storm episodes. The coping mechanisms adopted by residents during the dust storm, includes closing doors and windows and using face masks. The study recommended that residents should remain indoors, wear face masks, plant trees and cover crops, among others.
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Corte, Guilherme N., Thomas A. Schlacher, Helio H. Checon, Carlos A. M. Barboza, Eduardo Siegle, Ross A. Coelman et Antonia Cecília Z. Amaral. « Storm effects on intertidal invertebrates : increased beta diversity of few individuals and species ». PeerJ 5 (23 mai 2017) : e3360. http://dx.doi.org/10.7717/peerj.3360.
Texte intégralRésumé :
Climate change is predicted to lead to more extreme weather events, including changes to storm frequency, intensity and location. Yet the ecological responses to storms are incompletely understood for sandy shorelines, the globe’s longest land-ocean interface. Here we document how storms of different magnitude impacted the invertebrate assemblages on a tidal flat in Brazil. We specifically tested the relationships between wave energy and spatial heterogeneity, both for habitat properties (habitat heterogeneity) and fauna (β-diversity), predicting that larger storms redistribute sediments and hence lead to spatially less variable faunal assemblages. The sediment matrix tended to become less heterogeneous across the flat after high-energy wave events, whereas β-diversity increased after storms. This higher β-diversity was primarily driven by species losses. Significantly fewer species at a significantly lower density occurred within days to weeks after storms. Negative density and biomass responses to storm events were most prominent in crustaceans. Invertebrate assemblages appeared to recover within a short time (weeks to months) after storms, highlighting that most species typical of sedimentary shorelines are, to some degree, resilient to short-term changes in wave energy. Given that storm frequency and intensity are predicted to change in the coming decades, identifying properties that determine resilience and recovery of ecosystems constitute a research priority for sedimentary shorelines and beyond.
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Scharffenberg, Kevin C., Dustin Whalen, Shannon A. MacPhee, Marianne Marcoux, John Iacozza, Gail Davoren et Lisa L. Loseto. « Oceanographic, ecological, and socio-economic impacts of an unusual summer storm in the Mackenzie Estuary ». Arctic Science 6, no 2 (1 juin 2020) : 62–76. http://dx.doi.org/10.1139/as-2018-0029.
Texte intégralRésumé :
With increased warming and open water due to climate change, the frequency and intensity of storm surges is expected to increase. Although studies have shown that strong storms can negatively impact Arctic ecosystems, the impact of storms on Arctic marine mammals is relatively unknown. In July 2016, an unusually large storm occurred in the Mackenzie Delta while instrumented seabed moorings equipped with hydrophones and oceanographic sensors were in place to study environmental drivers of beluga habitat use during their summer aggregation. The storm lasted up to 88 h, with maximum wind speeds reaching 60 km/h; historical wind data from Tuktoyaktuk revealed a storm of similar duration has not occurred in July in at least the past 28 years. This provided a unique opportunity to study the impacts of large storms on oceanographic conditions, beluga habitat use, and the traditional subsistence hunt that occurs annually in the delta. The storm resulted in increased water levels and localized flooding as well as a significant drop in water temperature (∼10 °C) and caused belugas to leave the area for 5 days. Although belugas returned after the storm ended, the subsistence hunt was halted resulting in the lowest beluga harvest between 1978 and 2017.
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GORNISH, ELISE S., et THOMAS E. MILLER. « Effects of storm frequency on dune vegetation ». Global Change Biology 16, no 10 (19 août 2010) : 2668–75. http://dx.doi.org/10.1111/j.1365-2486.2009.02144.x.
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Hu, S., A. Bhattacharjee, J. Hou, B. Sun, D. Roesler, S. Frierdich, N. Gibbs et J. Whited. « Ionospheric storm forecast for high-frequency communications ». Radio Science 33, no 5 (septembre 1998) : 1413–28. http://dx.doi.org/10.1029/98rs02219.
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Osman Akan, A. « Derived Frequency Distribution for Storm Runoff Pollution ». Journal of Environmental Engineering 114, no 6 (décembre 1988) : 1344–51. http://dx.doi.org/10.1061/(asce)0733-9372(1988)114:6(1344).
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Li, Bo, Zongyu Yue, Shaojie Qu, Peiwen Yao, Xiaohui Fu, Zongcheng Ling et Shengbo Chen. « Spatio-Temporal Analysis of Dust Storm Activity in Chryse Planitia Using MGS-MOC Observations from Mars Years 24–28 ». Universe 7, no 11 (12 novembre 2021) : 433. http://dx.doi.org/10.3390/universe7110433.
Texte intégralRésumé :
Dust storms, observed in all seasons, are among the most momentous of Mars’ atmospheric activities. The Entry–Descent–Landing (EDL) activity of a Martian landing mission is influenced by local atmospheric conditions, especially the probability of dust storm activity. Chryse Planitia, featuring many of the largest and most prominent outflow channels and possible mud volcanoes, is an important target site for current and future Mars landing missions. It is of great significance to understand that a Mars landing probe may encounter a dust storm situation during EDL season in the Chryse Planitia. In this study, based on four Martian years, Mars Orbiter Camera (MOC) Mars Daily Global Maps (MDGMs), 1172 dust storms were identified within Chryse’s 1600 km-radius ring. Secondly, the daily mean dust storm probability was calculated, binned by 1° of solar longitude in the Chryse landing area. The two active periods of dust storm activity are Ls = 177–239° and Ls = 288–4°, with an average daily mean dust storm probability of 9.5% and 4.1%. Dust storm activity frequency is closely interrelated with the seasonal ebb and flow of the north polar ice cap; consequently, most dust storms occur in either the cap’s growth or recession phase. We divided the Chryse landing area into square grids of 0.5° and computed the average probability of dust storm occurrence in each grid, which ranged from 0.19% to 2.42%, with an average of 1.22%. The dust storm activity probability in space was also inhomogeneous—low in the west and south but high in the east and north—which was mainly affected by the origin and the path of dust storm sequences. Based on empirical orthogonal function (EOF) analysis of storms in the Chryse area, 40.5% are cap-edge storms in the northern hemisphere. Finally, we concluded that the preferred time of a Mars landing mission is Ls = 18–65° in the Chryse Planitia, and three preferred landing areas were selected with low dust storm probability.
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Frifra, A., M. Maanan, H. Rhinane et M. Maanan. « AN ARTIFICIAL INTELLIGENCE APPROACH TO PREDICTION OF EXTREME EVENTS : THE CASE OF STORMS IN WESTERN FRANCE ». International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVI-4/W3-2021 (10 janvier 2022) : 115–22. http://dx.doi.org/10.5194/isprs-archives-xlvi-4-w3-2021-115-2022.
Texte intégralRésumé :
Abstract. Storms represent an increased source of risk that affects human life, property, and the environment. Prediction of these events, however, is challenging due to their low frequency of occurrence. This paper proposed an artificial intelligence approach to address this challenge and predict storm characteristics and occurrence using a gated recurrent unit (GRU) neural network and a support vector machine (SVM). Historical weather and marine measurements collected from buoy data, as well as a database of storms containing all the extreme events that occurred in Brittany and Pays de la Loire regions, Western France, since 1996, were used. Firstly, GRU was used to predict the characteristics of storms (wind speed, pressure, humidity, temperature, and wave height). Then, SVM was introduced to identify storm-specific patterns and predict storm occurrence. The approach adopted leads to the prediction of storms and their characteristics, which could be used widely to reduce the awful consequences of these natural disasters by taking preventive measures.
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Medina-Elizalde, Martín, Josué Moises Polanco-Martínez, Fernanda Lases-Hernández, Raymond Bradley et Stephen Burns. « Testing the “tropical storm” hypothesis of Yucatan Peninsula climate variability during the Maya Terminal Classic Period ». Quaternary Research 86, no 2 (septembre 2016) : 111–19. http://dx.doi.org/10.1016/j.yqres.2016.05.006.
Texte intégralRésumé :
AbstractWe examine the “tropical storm” hypothesis that precipitation variability in the Yucatan Peninsula (YP) was linked to the frequency of tropical cyclones during the demise of the Classic Maya civilization, in the Terminal Classic Period (TCP, AD 750—950). Evidence that supports the hypothesis includes: (1) a positive relationship between tropical storm frequency and precipitation amount over the YP today (proof of feasibility), (2) a statistically significant correlation between a stalagmite (Chaac) quantitative precipitation record from the YP and the number of named tropical cyclones affecting this region today (1852—2004) (calibration sensu lato), and, (3) correlations between the stalagmite Chaac precipitation record and an Atlantic basin tropical cyclone count record and two proxy records of shifts in macroscale climate and ocean states that influence Atlantic tropical cyclongenesis. At face value, regional paleotempestology proxy records suggest that tropical storm activity in the YP was either similar or significantly lower than today during the TCP. The “tropical storm” hypothesis has implications for our understanding of the role the hydrological cycle played in the collapse of Classic Maya polities and the role of tropical storms in possibly ameliorating future drought in the YP and other tropical regions.
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Lombardo, Kelly. « Squall Line Response to Coastal Mid-Atlantic Thermodynamic Heterogeneities ». Journal of the Atmospheric Sciences 77, no 12 (décembre 2020) : 4143–70. http://dx.doi.org/10.1175/jas-d-20-0044.1.
Texte intégralRésumé :
AbstractIdealized 3D numerical simulations are used to quantify the impact of moving marine atmospheric boundary layers (MABLs) on squall lines in an environment representative of the U.S. mid-Atlantic coastal plain. Characteristics of the MABL, including depth and potential temperature, are varied. Squall lines are most intense while moving over the deepest MABLs, while the storm encountering no MABL is the weakest. Storm intensity is only sensitive to MABL temperature when the MABL is sufficiently deep. Collisions between the storm cold pools and MABLs transition storm lift from surface-based cold pools to wavelike features, with the resulting ascent mechanism dependent on MABL density, not depth. Bores form when the MABL is denser than the cold pool and hybrid cold pool–bores form when the densities are similar. While these features support storms over the MABL, the type of lifting mechanism does not control storm intensity alone. Storm intensity depends on the amplification and maintenance of these features, which is determined by the ambient conditions. Isolated convective cells form ahead of squall lines prior to the cold pool–MABL collision, resulting in a rain peak and the eventual discrete propagation of the storms. Cells form as storm-generated high-frequency gravity waves interact with gravity waves generated by the moving marine layers, in the presence of reduced stability by the squall line itself. No cells form in the presence of the storm or the MABL alone.
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Butler, H. Lee, et Mark D. Prater. « INNOVATIVE DETERMINATION OF NEARSHORE FLOOD FREQUENCY ». Coastal Engineering Proceedings 1, no 20 (29 janvier 1986) : 181. http://dx.doi.org/10.9753/icce.v20.181.
Texte intégralRésumé :
Reliable estimates of coastal flooding from tides and storm surges are required for making sound engineering decisions regarding the design, operation and maintenance of many coastal projects. A recent investigation of flood frequency along the coast and within the bays of southern Long Island, New York, produced new and optimal approaches to obtain meaningful statistical estimates of flood levels. This paper summarizes various elements of the study and concentrates on the problem of stage-frequency computations in the inland bay areas. Methods for optimizing the number of necessary storm/tide simulations and estimating the accuracy of results are presented.
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Ivanova, A. R., E. N. Skriptunova, N. I. Komasko et A. A. Zavialova. « Impact of dust and sand storms on the aviation operation and assessment of conditions for their occurrence at aerodromes in European Russia ». Hydrometeorological research and forecasting 4 (décembre 2020) : 78–95. http://dx.doi.org/10.37162/2618-9631-2020-4-78-95.
Texte intégralRésumé :
A review of literature on the impact of dust and sand storms on the air transport operation is presented. Observational data on dust storms at the aerodromes of European Russia for the period of 2001-2019 are analyzed. The seasonal variations in dust transport episodes at aerodromes and its relationship with visibility changes are discussed. The characteristics of dusty air masses and advection are given. It is concluded that the frequency of dust transfer episodes for the aerodromes under study has decreased over the past five years, except for Gumrak aerodrome (Volgograd). Keywords: dust storm, sand storm, aviation, visibility, seasonal variations, aerodrome оf European Russia
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Tahvildari, Navid, Akash Sahu, Yawen Shen, Mohamed Morsy et Jonathan Goodall. « COMBINED EFFECT OF STORM SURGE AND OVERLAND FLOW ON FLOODING IN A COASTAL URBAN AREA ». Coastal Engineering Proceedings, no 36 (30 décembre 2018) : 52. http://dx.doi.org/10.9753/icce.v36.currents.52.
Texte intégralRésumé :
The coastal regions in the U.S. East Coast and the Gulf of Mexico are under the risk of storm surge and precipitation-driven flooding. The adverse impacts of climate change including sea level rise (SLR), potential increase in intensity and frequency of extreme storms, and increase in precipitation intensity increases the vulnerability of coastal communities to flooding. The common practice for flood hazard assessment in urban coastal areas can result in some errors as the effect of storm surge and overland flow are not considered simultaneously. In this study, we combine the results of two hydrodynamic models, one for overland flow and the other for storm surge inundation, to develop an improved approach for flood hazard assessment.
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Lin, Jyh-Woei. « Geomagnetic Storm Related to Disturbance Storm Time Indices ». European Journal of Environment and Earth Sciences 2, no 6 (5 novembre 2021) : 1–3. http://dx.doi.org/10.24018/ejgeo.2021.2.6.199.
Texte intégralRésumé :
The magnitude of the Disturbance Storm Time (Dst) index varied in relation to the extremely small negative integer that indicated a large geomagnetic storm. The large sharpened variants of negative Dst indices could describe the detailed features of a geomagnetic storm. the Dst index was estimated using an algorithm through time and frequency-domain band-stop filtering to remove the solar-quiet variation and the mutual coupling effects between the Earth’s rotation, the Moon’s orbit, and the Earth’s orbit around the Sun. A good geomagnetic model that could describe the true variations in the geomagnetic field when undergoing diverse space weather, and one that could even predict variations in the geomagnetic field with a high accuracy. A suitable temporal resolution for the Dst index was per hour.
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Nwankwo, Victor U. J., William Denig, Sandip K. Chakrabarti, Olugbenga Ogunmodimu, Muyiwa P. Ajakaiye, Johnson O. Fatokun, Paul I. Anekwe, Omodara E. Obisesan, Olufemi E. Oyanameh et Oluwaseun V. Fatoye. « Diagnostic study of geomagnetic storm-induced ionospheric changes over very low-frequency signal propagation paths in the mid-latitude D region ». Annales Geophysicae 40, no 4 (4 juillet 2022) : 433–61. http://dx.doi.org/10.5194/angeo-40-433-2022.
Texte intégralRésumé :
Abstract. We performed a diagnostic study of geomagnetic storm-induced disturbances that are coupled to the mid-latitude D region by quantifying the propagation characteristics of very low-frequency (VLF) radio signals from transmitters located in Cumbria, UK (call sign GQD), and Rhauderfehn, Germany (DHO), and received in southern France (A118). We characterised the diurnal VLF amplitudes from two propagation paths into five metrics, namely the mean amplitude before sunrise (MBSR), the midday amplitude peak (MDP), the mean amplitude after sunset (MASS), the sunrise terminator (SRT) and the sunset terminator (SST). We analysed and monitored trends in the variation of signal metrics for up to 20 storms to relate the deviations in the signal amplitudes that were attributable to the storms. Five storms and their effects on the signals were examined in further detail. Our results indicate that relative to pre-storm levels the storm day MDP exhibited characteristic decreases in about 80 % (67 %) of the events for the DHO-A118 (GQD-A118) propagation path. The MBSR showed decreases of about 60 % (77 %), whereas the MASS decreased by 67 % (58 %). Conversely, the SRT and SST showed amplitude decreases of 33 % (25 %) and 47 % (42 %), respectively. Of the two propagation paths, the amplitude decreases for the DHO-A118 propagation path signal were greater, as previously noted by Nwankwo et al. (2016). To better understand the state of the ionosphere over the signal propagation paths and how it might have affected the VLF amplitudes, we further analysed the virtual heights (h'E, h'F1 and h'F2) and critical frequencies (foE, foF1 and foF2) from ionosondes located near the transmitters. The results of this analysis showed significant increases and fluctuations in both the F-region critical frequencies and virtual heights during the geomagnetic storms. The largest increases in the virtual heights occurred near the DHO transmitter in Rhauderfehn (Germany), suggesting a strong storm response over the region which might account for the larger MDP decrease along the DHO-A118 propagation path.
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Andersen, Mikkel René, Elvira de Eyto, Mary Dillane, Russell Poole et Eleanor Jennings. « 13 Years of Storms : An Analysis of the Effects of Storms on Lake Physics on the Atlantic Fringe of Europe ». Water 12, no 2 (21 janvier 2020) : 318. http://dx.doi.org/10.3390/w12020318.
Texte intégralRésumé :
While winter storms are generally common in western Europe, the rarer summer storms may result in more pronounced impacts on lake physics. Using long-term, high frequency datasets of weather and lake thermal structure from the west of Ireland (2005 to 2017), we quantified the effects of storms on the physical conditions in a monomictic, deep lake close to the Atlantic Ocean. We analysed a total of 227 storms during the stratified (May to September, n = 51) and non-stratified (November to March, n = 176) periods. In winter, as might be expected, changes were distributed over the entire water column, whereas in summer, when the lake was stratified, storms only impacted the smaller volume above the thermocline. During an average summer (May–September) storm, the lake number dropped by an order of magnitude, the thermocline deepened by an average of 2.8 m, water column stability decreased by an average of 60.4 j m−2 and the epilimnion temperature decreased by a factor of five compared to the average change in winter (0.5 °C vs. 0.1 °C). Projected increases in summer storm frequency will have important implications for lake physics and biological pathways.
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Gaál, L., P. Molnar et J. Szolgay. « Selection of intense rainfall events based on intensity thresholds and lightning data in Switzerland ». Hydrology and Earth System Sciences 18, no 5 (6 mai 2014) : 1561–73. http://dx.doi.org/10.5194/hess-18-1561-2014.
Texte intégralRésumé :
Abstract. This paper presents a method to identify intense warm season storms with convective character based on intensity thresholds and the presence of lightning, and analyzes their statistical properties. Long records of precipitation and lightning data at 4 stations and 10 min resolution in different climatological regions in Switzerland are used. Our premise is that thunderstorms associated with lightning generate bursts of high rainfall intensity. We divided all recorded storms into those accompanied by lightning and those without lightning and found the threshold I* that separates intense events based on peak 10 min intensity Ip ≥ I* for a chosen misclassification rate α. The performance and robustness of the selection method was tested by investigating the inter-annual variability of I* and its relation to the frequency of lightning strikes. The probability distributions of the main storm properties (rainfall depth R, event duration D, average storm intensity Ia and peak 10 min intensity Ip) for the intense storm subsets show that the event average and peak intensities are significantly different between the stations. Non-parametric correlations between the main storm properties were estimated for intense storms and all storms including stratiform rain. The differences in the correlations between storm subsets are greater than those between stations, which indicates that care must be exercised not to mix events of different origin when they are sampled for multivariate analysis, for example, copula fitting to rainfall data.
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Gaal, L., P. Molnar et J. Szolgay. « Selection of intense rainfall events based on intensity thresholds and lightning data in Switzerland ». Hydrology and Earth System Sciences Discussions 11, no 1 (14 janvier 2014) : 593–628. http://dx.doi.org/10.5194/hessd-11-593-2014.
Texte intégralRésumé :
Abstract. This paper presents a method to identify intense warm season storms of convective character based on intensity thresholds and lightning, and analyzes their statistical properties. Long records of precipitation and lightning data at 4 stations and 10 min resolution in different climatological regions in Switzerland are used. Our premise is that thunderstorms associated with lightning generate bursts of high rainfall intensity. We divided all storms into those accompanied by lightning and those without lightning and found the threshold I* that separates intense events based on peak 10 min intensity Ip ≥ I* for a chosen misclassification rate α. The performance and robustness of the selection method was tested by investigating the inter-annual variability of I* and its relation to the frequency of lightning strikes. The probability distributions of the main storm properties (rainfall depth R, event duration D, average storm intensity Ia and peak 10 min intensity Ip) for the intense storm subsets show that the event average and peak intensities are significantly different between the stations, and highest in Lugano in southern Switzerland. Non-parametric correlations between the main storm properties were estimated for the subsets of intense storms and all storms including stratiform rain. The differences in the correlations between storm subsets are greater than those between stations, which indicates that care must be exercised not to mix events when they are sampled for multivariate analysis, e.g. copula fitting to rainfall data.