2012年春节期间广东罕见低温阴雨天气特点及成因

利用常规气象观测资料、NCEP/NCAR分析资料,以及国家气候中心的海温监测资料等,初步分析了2012年春节前后广东极端低温阴雨天气过程的特点和成因。结果表明,此次过程具有极端温度低、低温范围广、阴雨时间长的特征;此次罕见天气过程是在＂北极涛动＂负位相活动和显著＂拉尼娜＂事件背景下发生,与欧亚地区持续大气环流异常密切相关。乌拉尔山阻塞高压建立后,中高纬稳定的＂两脊一槽＂形势下,有利于短波槽东南移影响华南;同时,高原南侧的南支西风槽加深增强了低纬水汽往华南地区输送,冷暖空气在华南长时间交绥,造成了持续的低温阴雨过程。过程期间,粤北近地层极端气温低,但中层暖层无论从强度、厚度及持续时间均未有2008年明显,因此过程主要以＂低温＂和＂阴雨＂为主,并未发生类似2008年初的粤北持续大范围＂低温雨雪冰冻＂天气。

Causality Analysis of the Unusual Cold and Rainy Weather in Guangdong during the Spring Festival of 2012

Guangdong suffered sustained cold and rainy weather during the Spring Festival of 2012.Based on the meteorological observation data and NCEP reanalysis data,the characteristics and the possible causes of the cold and rainy weather are analyzed.The results show that this case is associated with the Arctic Oscillation(AO),La Nina Event and anomalous atmospheric circulation.The "two-ridges and one-trough" circulation pattern in mid-high latitudes with the blocking high located over Urals Mts.was favorable for the south-eastward propagation of short wave troughs.The cold air associated with the short wave troughs moving southward from mid-high latitudes and butting up against moist southerly from the Bay of Bengal and the South China Sea produced a quasi-stationary front at Southern China,which caused the continuous cold and rainy weather.