广西持续性低温雨雪冰冻过程特征和气候成因分析

Analysis on the characteristics and climatic causes of the persistent low temperature and snow freezing process in Guangxi

应用广西境内国家气象站逐日降水量、气温资料,定义了区域持续性低温雨雪冰冻过程。利用NCEP/NCAR逐日再分析等资料,使用合成分析等方法,研究了广西持续性低温雨雪冰冻过程的特征和气候成因。结果表明:(1)广西持续性低温雨雪冰冻过程在1980s之前平均出现次数为4次·10a^(-1),过程平均日数为40d·10a^(-1),而在1990s之后平均出现次数为2次·10a^(-1),过程平均日数为23.7d·10a^(-1)。(2)持续性低温雨雪冰冻过程期间,亚洲大陆中低纬度地区冬季气温整体偏冷,500hPa位势高度距平场在亚洲50oN以北地区为正距平,以南为负距平,有大型稳定的长波斜脊横槽活动,华南上空由低层向高层有暖平流。

The regional persistent processes of low temperature and freezing rain weather is defined by using the daily precipitation and temperature data of the national meteorological station in Guangxi. Using NCEP/NCAR daily reanalysis data and synthetic analysis method,the characteristics and climatic causes of persistent low temperature and snow freezing process in Guangxi were studied.The results show that(1) the persistent processfrequency of low temperature and freezing rain weather in Guangxi were 4 times /10a before 1980s,and the average days of a process was 40d/10a,after 1990s,the frequency was 2 times/10a,and the average days was 23.7d/10a.(2) During the period of persistent low temperature and freezing rain,the winter air temperature in the middle and low latitudes of the Asian continent is generally cold. In the north of 50°N Asia,the 500hPa geopotential height anomaly field is positive while the south is negative. Beside large and stable long-wave oblique ridgesand transverse troughs,from the lower to the upper level,there are warm advections over South China.