Analysis on Characteristics of Atmospheric Circulation and Low Temperature Disturbance of Long-Term Catastrophic Freezing Weather in Guangxi
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Abstract:
Using conventional observation and NCEP reanalysis data, the catastrophic freezing weather process (low-temperature process for short) in Guangxi during 2008-2019 are analyzed. The results show that the low-temperature process in Guangxi was divided into stable blocking, weakened blocking, trough-ridge, and fluctuation. The stable blocking process lasted 8 to 15 days, and the rest type was 6 days or less. The cold air constantly supplied from high latitudes and the water vapour transported from low latitudes were two essential factors for continuing the low-temperature process in Guangxi. Water vapour and heat provided by southwest wind at 700 hPa were conducive to melting layer formation and freezing rain. The wide temperature front area and high value of average frontogenetic function were favourable for the long time low-temperature process. There was freezing rain temperature stratification with cloud top temperature of -10 to 0 ℃, low layer cold pad ≤-7 ℃, middle layer melting layer ≥8 ℃ in stable blocking and pure snow temperature stratification with cloud top temperature of -20 to -10 ℃, no melting layer, and low layer cold pad temperature of -10 ℃ in trough-ridge. Path of Low-temperature disturbance (LTD) in stable blocking was “east+west” path, and those of other types were east path. The previous strong LTD had instructive significance. LTD first moved southward from Lake Baikal to the north of Guangxi, then eastward from Lake Balkhash along the plateau’s north in the “east+west” path process. The continuous supplement of LTD in the area of 75°E near Lake Balkhash played an important role. Based on the location of the previous LTD and the circulation, the path and duration of the low-temperature process could be judged preliminarily.
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.