- Dept of Atmospheric and Environmental Sciences
University at Albany/SUNY/ES-351
1400 Washington Avenue
Albany, NY 12222 - 518-442-4564
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A preliminary analytical study has been made of the synoptic situations associated with thunderstorms that initiate upward-moving leaders from the towers on the Mt. San Salvatore near Lugano, Switzerland. Synoptic situations at the time... more
A preliminary analytical study has been made of the synoptic situations associated with thunderstorms that initiate upward-moving leaders from the towers on the Mt. San Salvatore near Lugano, Switzerland. Synoptic situations at the time of the lightning occurrences were divided into six categories based on the surface weather and flow pattern during the period 1967–1969 at Lugano. Cloud thicknesses were estimated from the LFC (Level of Free Convection) and LCL (Lifting Condensation Level) from the mean sounding at Milan. Large cloud thicknesses were found to be associated with the combined upward and downward discharges and smaller cloud thicknesses were associated with only upward discharges (flashes initiated by upward moving stepped leaders). Furthermore, the large cloud thicknesses were associated with the thunder-storms that had proportionally more flashes to the surrounding countryside than to the tower itself. We offer the speculation that the difference in upward and downward discharges to the towers with associated synoptic situations may be explained on the basis of a deficiency of large raindrops which are believed to be necessary for the initiation of downward discharges. DOI: 10.1111/j.2153-3490.1974.tb01627.x
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... 1983; Bosart and Sanders 1986; Zack and Kaplan 1987;Bosart and Seimon 1988; Branick et al. 1988; Koch and Golus 1988; Schneider 1990; Bauck 1992; Ralph et al. 1993; Ramamurthy et al. 1993; Bracken 1995; Koch and O'Handley... more
... 1983; Bosart and Sanders 1986; Zack and Kaplan 1987;Bosart and Seimon 1988; Branick et al. 1988; Koch and Golus 1988; Schneider 1990; Bauck 1992; Ralph et al. 1993; Ramamurthy et al. 1993; Bracken 1995; Koch and O'Handley 1997; Bosart et al. 1998). ...
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High‐resolution Taiwan Climate Change Projection Information and Adaptation Knowledge Platform (TCCIP) gridded precipitation data are used to characterize days in the Mei‐yu season with the most extreme precipitation (EP). These “EP days”... more
High‐resolution Taiwan Climate Change Projection Information and Adaptation Knowledge Platform (TCCIP) gridded precipitation data are used to characterize days in the Mei‐yu season with the most extreme precipitation (EP). These “EP days” are grouped into weather types based on the presence of features such as tropical cyclones (TCs) and atmospheric rivers (ARs), then analyzed from the perspective of weather type frequency and synoptic changes. During the 1979–2019 period, EP days associated with ARs were associated with significant increasing trends in season‐total precipitation. These AR‐related precipitation increases are due to four events in 2005, 2006, 2012, and 2017 which had long duration and unusually intense precipitation, and which were anomalous even within the longer 1960–2019 time period. Meanwhile, TC‐related EP days contribute less precipitation than they did in the 1980s due to decreased frequency of TCs on EP days and in the Mei‐yu season climatology. Over the 1979–2019 period, the AR‐related and TC‐related trends combine to produce EP increases in western Taiwan and decreases in eastern Taiwan. Mei‐yu season southwesterly integrated vapor transport (IVT), wind speed, and specific humidity have all increased in association with these extreme events. Low‐level winds appear to the primary factor influencing the IVT increase, with increased moisture also contributing. The wind trends are consistent with climatological pressure increases south of Taiwan and decreases over the East Asian landmass, which facilitate a strengthened circulation in a corridor extending from the southern China coastline over Taiwan during this season.
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A detailed synoptic and mesoscale analysis is conducted of an intense convective outbreak which struck much of Israel, Jordan, Lebanon and Syria in early March 1980. Severe winter weather caused considerable personal hardship and economic... more
A detailed synoptic and mesoscale analysis is conducted of an intense convective outbreak which struck much of Israel, Jordan, Lebanon and Syria in early March 1980. Severe winter weather caused considerable personal hardship and economic disruption over a wide area.The planetary‐scale circulation featured a confluent flow pattern across North Africa and southern Europe downstream of a block just west of the Greenwich meridian. A strong subtropical jet stream was maintained across North Africa in the confluent flow regime. Synoptic‐scale disturbances from the Atlantic were diverted northward across Scandinavia from where they plunged south‐eastward toward the Mediterranean to the west of the Black Sea. A series of three disturbances, the last being the most powerful, swept through the eastern Mediterranean as the vortex settled south‐eastward toward the Middle East.Our analysis of the available evidence has established that three physical mechanisms contributed primarily to the extreme nature of the event. First, the steady south‐eastward movement of mobile short wave troughs resulted in the progressive cooling of the lower and middle troposphere over the eastern Mediterranean Sea and the Middle East. Second, sea surface heat and moisture fluxes contributed to destabilization and the generation of extreme instability where the cold air from higher latitudes had a long overwater fetch. Third, exceptionally heavy precipitation fell where a strong low‐level moist, unstable westerly air stream impinged on the coastal mountains. The strong westerly flow was generated to the south of an intense subsynoptic‐scale vortex that formed in the lower and mid troposphere as the updraught region of a powerful short‐wave‐trough/ jet‐streak system aloft ingested air that had been destabilized below.
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The wind industry in the United States has experienced a remarkably rapid expansion of capacity in recent years and this fast growth is expected to continue in the future 1-3. While converting wind's kinetic energy into electricity, wind... more
The wind industry in the United States has experienced a remarkably rapid expansion of capacity in recent years and this fast growth is expected to continue in the future 1-3. While converting wind's kinetic energy into electricity, wind turbines modify surface-atmosphere exchanges and the transfer of energy, momentum, mass and moisture within the atmosphere 4-6. These changes, if spatially large enough, may have noticeable impacts on local to regional weather and climate. Here we present observational evidence for such impacts based on analyses of satellite data for the period of 2003-2011 over a region in west-central Texas, where four of the world's largest wind farms are located 7. Our results show a significant warming trend of up to 0.72 • C per decade, particularly at night-time, over wind farms relative to nearby non-wind-farm regions. We attribute this warming primarily to wind farms as its spatial pattern and magnitude couples very well with the geographic distribution of wind turbines. Despite debates regarding the possible impacts of wind farms on regional to global scale weather and climate 8-12 , modelling studies agree that they can significantly affect local scale meteorology 6,13-16 by increasing surface roughness, changing the stability of the atmospheric boundary layer (ABL) and enhancing turbulence in the rotor wakes 4-6. However, these studies are based primarily on numerical simulations of regional and global models, which owing to lack of observations only crudely represent the effects of wind turbines by explicitly increasing either surface roughness length or turbulence kinetic energy. Evidently, more realistic model parameterizations should be developed and modelling results should be validated against the observations. Although observed data on wind speed and turbulence in and around operational wind farms are readily available, information on other meteorological variables does not exist in the public domain. A recent study using the only available observed temperature data from an operational wind farm shows a warming effect at night and a cooling effect during the day 6. However, the observed data are from only two meteorological towers for a period of 1.5 months. Hence more observational evidence, particularly on larger scales and for longer periods, is needed. Satellites provide information on global spatial sampling at regular temporal intervals and thus have the potential to accurately monitor and detect the impacts of large wind farms with spatial detail. This study aims to search for observational evidence of such impacts from land surface temperature (LST) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) with spatial resolutions finer than most wind farms and temporal resolutions covering both days and nights. LST is the radiometric