The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Andrew J. Dowdy - One of the best experts on this subject based on the ideXlab platform.
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The differing role of weather systems in southern Australian rainfall between 1979–1996 and 1997–2015
Climate Dynamics, 2021Co-Authors: Acacia S. Pepler, Andrew J. Dowdy, Pandora HopeAbstract:Most of the rainfall in southern Australia is associated with cyclones, cold fronts, and Thunderstorms, and cases when these weather systems co-occur are particularly likely to cause extreme rainfall. Rainfall declines in some parts of southern Australia during the cool half of the year in recent decades have previously been attributed to decreases in the rainfall from fronts and/or cyclones, while Thunderstorm-related rainfall has been observed to increase, particularly in the warm half of the year. However, the co-occurrence of these systems, particularly the co-occurrence of cyclones or fronts with Thunderstorms, can be very important for rainfall in some areas, particularly heavy rainfall, and changes in the frequency of these combined weather systems have not been previously assessed. In this paper we show that the majority of the observed cool season rainfall decline between 1979–1996 and 1997–2015 in southeast Australia is associated with a decrease in the frequency of fronts and cyclones that produce rainfall, while there has simultaneously been an increase in the frequency of cold fronts and Thunderstorms that do not produce rainfall in some regions. Thunderstorm rainfall has increased in much of southern Australia, particularly during the warm half of the year, including an increase in rainfall where a Thunderstorm environment occurs at the same time as a cyclone or front.
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Seasonal forecasting of lightning and Thunderstorm activity in tropical and temperate regions of the world
Scientific Reports, 2016Co-Authors: Andrew J. DowdyAbstract:Thunderstorms are convective systems characterised by the occurrence of lightning. Lightning and Thunderstorm activity has been increasingly studied in recent years in relation to the El Niño/Southern Oscillation (ENSO) and various other large-scale modes of atmospheric and oceanic variability. Large-scale modes of variability can sometimes be predictable several months in advance, suggesting potential for seasonal forecasting of lightning and Thunderstorm activity in various regions throughout the world. To investigate this possibility, seasonal lightning activity in the world's tropical and temperate regions is examined here in relation to numerous different large-scale modes of variability. Of the seven modes of variability examined, ENSO has the strongest relationship with lightning activity during each individual season, with relatively little relationship for the other modes of variability. A measure of ENSO variability (the NINO3.4 index) is significantly correlated to local lightning activity at 53% of locations for one or more seasons throughout the year. Variations in atmospheric parameters commonly associated with Thunderstorm activity are found to provide a plausible physical explanation for the variations in lightning activity associated with ENSO. It is demonstrated that there is potential for accurately predicting lightning and Thunderstorm activity several months in advance in various regions throughout the world.
B. Grefenstette - One of the best experts on this subject based on the ideXlab platform.
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Thunderstorm characteristics associated with RHESSI identified terrestrial gamma ray flashes
Journal of Geophysical Research: Space Physics, 2010Co-Authors: M.e. Splitt, S. M. Lazarus, Bryna Hazelton, J R Dwyer, H K Rassoul, D. Barnes, D.m. Smith, B. GrefenstetteAbstract:The characteristics of Thunderstorms that produce terrestrial gamma-ray flashes (TGFs) observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) are determined using climatological and meteorological data. RHESSI observed TGFs follow diurnal, seasonal, and geographic patterns that are very similar to those of Thunderstorms confirming, in part, that these events are directly connected to Thunderstorm activity. The TGF producing Thunderstorms are shown to be closely associated with tall (ranging from 13.6 km to 17.3 km) tropical Thunderstorm systems, a finding that is consistent with theoretical expectations from models of relativistic breakdown that relate the source region to the spectral signatures observed by RHESSI. Unlike sprites, there appears to be no predilection for TGFs to occur with large Thunderstorm complexes. Rather, TGF producing Thunderstorms are shown to range in areal extent by several orders of magnitude. Analysis of a single TGF event within the Mozambique Channel indicates an elevated mixed phase (both liquid water and ice present) level of approximately 6 km which is consistent with the climatological findings.
Stanley A. Changnon - One of the best experts on this subject based on the ideXlab platform.
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Thunderstorm Rainfall in the Conterminous United States
Bulletin of the American Meteorological Society, 2001Co-Authors: Stanley A. ChangnonAbstract:Abstract Thunderstorm rainfall amounts during the 1950–94 period were determined for 51 first–order stations distributed across the United States, and these values were assessed for seasonal and annual variations in both space and time. Thunderstorms produce 48% of the average annual precipitation received in the Mississippi River basin, which embraces 41% of the United States. Hence, the temporal and spatial variations in Thunderstorm rainfall are major factors affecting most of the nation's water cycle. However, Thunderstorm rainfall is only a small part of the total precipitation on the West Coast, typically less than 10% of the annual total. Thunderstorms maximize in the summer in most areas and produce 72% of the total summer rainfall that occurs east of the Rocky Mountains. Thunderstorm rainfall in the spring exceeds summer values in the southern plains and portions of California with 40% of the annual average storm precipitation, but spring values rank second in most areas of the nation. Thundersto...
M.e. Splitt - One of the best experts on this subject based on the ideXlab platform.
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Thunderstorm characteristics associated with RHESSI identified terrestrial gamma ray flashes
Journal of Geophysical Research: Space Physics, 2010Co-Authors: M.e. Splitt, S. M. Lazarus, Bryna Hazelton, J R Dwyer, H K Rassoul, D. Barnes, D.m. Smith, B. GrefenstetteAbstract:The characteristics of Thunderstorms that produce terrestrial gamma-ray flashes (TGFs) observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) are determined using climatological and meteorological data. RHESSI observed TGFs follow diurnal, seasonal, and geographic patterns that are very similar to those of Thunderstorms confirming, in part, that these events are directly connected to Thunderstorm activity. The TGF producing Thunderstorms are shown to be closely associated with tall (ranging from 13.6 km to 17.3 km) tropical Thunderstorm systems, a finding that is consistent with theoretical expectations from models of relativistic breakdown that relate the source region to the spectral signatures observed by RHESSI. Unlike sprites, there appears to be no predilection for TGFs to occur with large Thunderstorm complexes. Rather, TGF producing Thunderstorms are shown to range in areal extent by several orders of magnitude. Analysis of a single TGF event within the Mozambique Channel indicates an elevated mixed phase (both liquid water and ice present) level of approximately 6 km which is consistent with the climatological findings.
Madhuparna Mukherjee - One of the best experts on this subject based on the ideXlab platform.
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Thunderstorms, Lightning, Sprites and Magnetospheric Whistler-Mode Radio Waves
Surveys in Geophysics, 2008Co-Authors: Devendraa Siingh, A. K. Singh, R. P. Patel, Rajesh Singh, R. P. Singh, B. Veenadhari, Madhuparna MukherjeeAbstract:Thunderstorms and the lightning that they produce are inherently interesting phenomena that have intrigued scientists and mankind in general for many years. The study of Thunderstorms has rapidly advanced during the past century and many efforts have been made towards understanding lightning, Thunderstorms and their consequences. Recent observations of optical phenomena above an active lightning discharge along with the availability of modern technology both for data collection and data analysis have renewed interest in the field of Thunderstorms and their consequences in the biosphere. In this paper, we review the electrification processes of a Thunderstorm, lightning processes and their association with global electric circuit and climate. The upward lightning discharge can cause sprites, elves, jets, etc. which are together called transient luminous events. Their morphological features and effects in the mesosphere are reviewed. The wide spectrum of electromagnetic waves generated during lightning discharges couple the lower atmosphere with the ionosphere/magnetosphere. Hence various features of these waves from ULF to VHF are reviewed with reference to recent results and their consequences are also briefly discussed.
