1961—2008年华南区域寒潮变化的气候特征

利用华南三省(广东、广西、海南)192个台站1961年1月1日至2008年12月31日的逐日平均气温、日最低气温资料,分析了华南寒潮频次的气候特征及其变化;定义了一个表征华南寒潮强度的指数,由此分析了华南寒潮活动的强度变化。气候分析结果表明:华南在近48年中出现了221次寒潮过程,主要分布在10月至次年4月,以12月、1月、2月、3月为主,占88.7%;华南区域单站寒潮的年均发生频次和平均降温持续天数从内陆向沿海递减,平均最低气温从内陆到沿海逐渐增加,单站寒潮过程平均最大降温幅度在11.5～16.0℃。近48年来,华南寒潮活动在减少的趋势上还具有频数和强度上的月际、年际和年代际变化。发生特强寒潮和中等寒潮的比率从20世纪80年代以来逐渐减少,而发生弱寒潮比率显著增加,但2008年出现了近48年华南最强的寒潮。

Climatic Characteristics of Cold Waves in South China in the Period 1961-2008

Based on the daily minimum and mean temperature data of 192 stations in South China (Guangdong, Guangxi, and Hainan provinces) from 1 January 1961 to 31 December 2008, climatic characteristics and variations of cold wave frequency in South China were first analyzed. An intensity index of cold wave was defined and intensity changes of cold wave activities in South China were analyzed. The results of climatic analysis show that there were 221 times cold wave processes in South China in the last 48 years. The cold waves might occur in the period from October to April of the next year, and 88.7 % of them concentrated in December, January, February and March. It has been found that the mean annual frequency and mean temperature reduction of cold wave processes of single station gradually reduced but the mean minimum temperature gradually increased from north to south and from inland to coast in South China in the past 48 years. The mean maximum temperature reduction of cold wave processes of single station ranged from 11.5 to 16.0℃. In the last 48 years, cold wave activities in South China showed a generally declining trend, but its frequency and intensity still exhibited monthly, yearly and decadal variabilities. The ratios of strong and medium cold waves have gradually decreased since the 1980s, however the ratio of weak cold waves has significantly increased, and the strongest cold wave in the last 48 years occurred in South China in 2008.