不同定义指标下的乌鲁木齐寒潮过程气候特征对比分析

Analysis on the Climatic Characteristics of Cold Wave Processes with Different Indices in Urumqi

利用乌鲁木齐市1951—2015年逐日最低气温(TD)、日平均气温(TT)资料,依据《寒潮等级》国家标准,以TD、TT为定义指标来普查寒潮降温过程,采用数理统计方法对2种指标统计的寒潮降温气候变化特征进行对比分析。结果表明:2种指标方法统计的降温频数存在显著性差异,在年际、季节时间尺度上均呈不显著减少趋势,TT法统计的年降温频数减少趋势显著强于TD法;90%的降温过程持续时间在1~3 d,TD、TT法统计的最长降温持续日数均出现在11月,且不同降温幅度的频数最大值亦在秋季;以TD、TT法统计的全年95.5%和94.6%的降温过程达不到寒潮的标准,2种方法统计的寒潮等级频数均表现为一般寒潮>强寒潮>特强寒潮;2种方法统计的寒潮频数在年际、季节尺度上均呈现减少趋势,峰值期分别为4月和10月,20世纪50年代为多发期,2001—2015年为相对少发期;TT法统计寒潮频数未来持续性强度弱于TD法;相关性分析发现,寒潮频数与年均TD、TT呈极显著的负相关关系,且年均TD的相关性强于年均TT,表明TD是影响寒潮频数变化的一个重要指标参数。

Based on the data of daily minimum temperature （TD）and daily mean temperature（TT）of Urumqi from 1951 to 2015,TD and TT were taken as the defining indexes to survey theprocesses of cold wave according to the GB of “Grades of clod wave” ,and the climaticcharacteristics of cold wave was analyzed by mathematical statistics. The results showed that therewere significant differences in the frequency of cooling by both methods,and no significant decreasein the annual and seasonal time scales,the decreasing tendency of the TT method was significantlystronger than that of the TD method. 90% of the cooling process was maintained with 1~3d,and thelongest days in the fall of November. 95.5% and 94.6% of the cooling process by two methodscouldn’ t reach to standard of clod wave,the grades frequency of cold wave with two methodsmanifestations included：cold wave〉strong cold wave〉super strong. The frequency of cold wave weredecreased in the annual and seasonal time scales,the peak period was appeared in April and inOctober and the frequent period of cold wave was appeared in the 1950s,the relatively lessOctober and the frequent period of cold wave was appeared in the 1950s the relatively lessoccurred period over the last 15 years. The development intensity of cold wave with TT method wasweaker than TD method; The correlation analysis indicated that there was a negative correlationbetween frequency of cold wave and TD、 TT. The analysis showed that TD was important parametersof the variation of cold wave frequency.