广西寒潮天气统计特征及环流形势分析

根据修订后的寒潮标准,对广西近46a的寒潮天气进行统计,并对典型寒潮年进行环流形势分析。结果表明:广西近46a出现了61次寒潮天气过程,其中全区性21次,桂北区域29次,桂南区域22次;广西寒潮最早出现在11月份,最迟出现在3月份,1月是寒潮出现的高峰月;出现寒潮频率的地域分布为东高西低;历年出现寒潮的总站数略呈下降趋势,并具有2年及11年左右的明显周期振荡特征。典型寒潮年环流分析表明当极涡南掉,东亚大槽加深,乌拉尔山脊维持,冬季风的加强及中纬度西风气流是导致冷空气堆积并爆发寒潮的主要环流形势。

Statistical Characteristics of Cold Wave Weather in Guangxi and Analysis of Circumfluence Situation

A statistic is made on cold wave weathers in the recent 46 years according to the revised standard for cold wave, and analyzes the circumfluence situation of typical cold wave years. The results indicate 61 cold wave weathers in Guangdxi in the recent 46 years, with 21 in the whole Guangxi range, 29 in the north part and 22 in the south part; the earliest cold wave weather occurs in November of the year and the latest one in March of the following year, with its peak in January; frequency distribution of cold wave is featured with a high rate in the east part and a low one in the west part; total numbers of observatory stations where cold wave happens decreases a little, and it is featured with an obvious 2-year and 11-year cycle fluctuation. Circumfluence analysis of the typical cold wave years makes clear the causes for stacking of cold air and the consequent breakout of cold wave are the southwards moving of pole eddy, deepening of the Eastern-Asian big trough, maintaining of Ural ridge, strengthening of winter monsoon and the westerly air current in the mid-latitude area.