Based on daily mean temperature and minimum temperature of 122 meteorological observation stations in Yunnan,the temporal and spatial variation characteristics of the number of occurrences of three types of cold air in winter half year from 1961 to 2014 over Yunnan are analyzed.The results show:① With climate warming,the overall trend of occurrences of the three types of cold air in Yunnan during the recent 54 years has been decreased uniformly,and general cold air decreased the most remarkably.Spatially,this reduction trend is consistent across the whole province.For the abrupt change point of reduction,general cold air appears near 2002,strong cold air appears near 1994 and cold wave near 1978.② The spatial distribution of occurrences of three types of cold air is not the same.General cold air decreases from northwest to south;strong cold air decreases from north and east to south and west;cold wave decreases from east to west.③ The three types of cold air mainly concentrate in December,January and February,of which the most is in January.In winter the number of cold air of low temperature form is more than dropping temperature form,while in spring and autumn the number of dropping temperature form is more than low temperature form.④ There are obvious interannual variations in three types of cold air,while evident interdecadal variations for general cold air and strong cold air.⑤ The overall features of spatial distribution of the earliest commencement date of three types of cold air delay from northwest and east to south and west.The latest dates of cold air in different area have a larger span and shows the general feature of delaying from south and west to north and east.The lasting days of three types of cold air differ greatly.⑥ There is a obvious inverse correlation relationship between the number of occurrence of three types of cold air and temperature,that is,the higher(lower) the temperature,the less(more) of the frequency of the cold air.%利用云南122个测站的日平均气温和最低气温资料,统计分析了1961-2014年间冬半年影响云南的三类冷空气的时空变化特征.结果表明:①随着气候变暖,影响云南的三类冷空气近54年的总趋势为一致性减少,减少最显著的是一般冷空气.从空间上看,这种减少趋势为全省一致性的.减少突变点一般冷空气发生在2002年附近,强冷空气出现在1994年附近,寒潮在1978年附近.②三类冷空气的空间分布不尽相同.一般冷空气从西北向南减少;强冷空从北向南,自东向西减少;寒潮自东向西减少.③三类冷空气主要集中在12月、1月和2月,其中1月最多.冬季低温型多于降温型,春季和秋季降温型多于低温型.④云南三类冷空气发生频次皆有明显的年际变化,一般冷空气和强冷空气还有明显的年代际变化.⑤三类冷空气最早初日总体皆呈由西北部和东部向南和向西逐步延迟的分布特征,最晚终日跨度较大,总体呈由南向北、由西向东逐步推后.三类冷空气维持时间相差较大.⑥三类冷空气与气温变化均呈反相关关系,即气温偏高(低),则三类冷空气频次偏少(多).
展开▼
