Comparison of Causes of Two Low Temperature Rain and Snow Weathers in Southern China
A wide-range low temperature rain and snow occurred in southern China at the end of 2018 and 2021 respectively,which made a severe damage to the life and production.As a result,it is of great significance to compare the formation factors of the two low temperature rain and snow weathers.The results show that:the northerly airflow in front of high pressure ridge lying the west side of the Lake Baikal accumulates at the rear of the downstream transverse trough which makes the Siberian high become stronger.The Rossby wave originating from the North Atlantic has energy dispersion in the blocking high regions,which is conducive to the weakening and collapse of blocking high.The cold air sweeps across China after the transverse trough turns to a meridional trough,resulting in strong cooling of the ground.At this time,the related strong cooling on the east and south sides of the Siberian high is controlled by the cold advection by low-frequency wind.The south branch trough in the low latitude is active,and the warm and wet air northward merges with the cold air from mid-high latitude,causing a wide range of rain,snow and freezing rain in southern China.However,compared with the process in 2018,the process in 2021 has shorter duration,smaller precipitation range and greater cooling amplitude in key regions.The reason is that Rossby wave energy disperses faster and the blocking high weakens more quickly which makes the cold air directly intrude China from mid-high latitude.While the cold air accumulates and transports westward near Lake Baikal,and then becomes weak when it penetrates southward in the 2018 process.
low temperature rain and snowblocking highSiberian highRossby wave
国家科技期刊平台
NSTL
万方数据
维普
