1981—2013年6—7月江淮地区切变线及暴雨统计分析

Statistical analysis of the shear lines and torrential rains over the Yangtze-Huaihe river region during June-July in 1981-2013

中文关键词:  江淮地区  切变线  暴雨  切变线暴雨  统计

英文关键词:Yangtze-Huaihe river region  Shear line  Torrential rain  Shear line torrential rain  Statistics

中文摘要:

      为了研究20世纪80年代以来的江淮切变线及暴雨的气候态特征,从而为未来的江淮切变线暴雨的业务预报和科研提供参考,利用欧洲中心风场再分析资料和地面气象站基本气象要素日值数据集(V3.0)的降水资料,通过纬向风的经向切变、相对涡度和纬向0风速线3个客观判据,统计了1981—2013年6—7月江淮地区暴雨、切变线以及切变线暴雨。结果表明:1981—2013年6—7月,江淮地区有30.2 d出现暴雨,有33.2 d出现切变线,22.0 d出现切变线暴雨,切变线暴雨日数占切变线日数的近2/3,占暴雨日数的近3/4;6—7月江淮地区出现切变线和暴雨的日数有不显著的年际增长趋势,增长率比江淮切变线暴雨大一个量级,而后者的日数在近33年基本维持不变。江淮地区的切变线日数、暴雨日数和切变线暴雨日数2000年前年际波动较大,2000年后年际波动较小。6—7月江淮地区的暴雨日数、切变线日数和切变线暴雨日数均存在一定的年代际变化特征,且三者的年代际变化特征较为一致,在1981—2007年,江淮地区降水量的年代际变化与暴雨日数、切变线日数和切变线暴雨日数的年代际变化较为一致。1995年前,6—7月江淮切变线暴雨日数存在2—3年的周期,1995年后没有显著的周期。在6月上中旬和7月中下旬,江淮切变线暴雨日数存在2—4 d的周期,在6月下旬到7月上旬,江淮切变线暴雨日数不存在明显周期,切变线暴雨日数在梅雨期内稳定维持,且江淮切变线暴雨最集中发生在6月下旬到7月上旬的梅雨期内,说明梅雨期降水以切变线引发的降水为主。

英文摘要:

      Using the ERA-Interim wind data and China's 756 meteorological station daily precipitation data, the shear line days, torrential rain days and shear line torrential rain days during June-July over the Yangtze-Huaihe river region in 1981-2013 have been selected by the 3 criteria of the meridional shear of zonal wind, relative vorticity, zero line of zonal wind. It is shown that during June and July from 1981 to 2013, 30.2 days (nearly 1 month) are torrential rain days, 33.2 days are shear line days, and 22.0 days are shear line torrential rain days. The shear line torrential rain days has accounted for nearly 2/3 of the shear line days and nearly 3/4 of the torrential rain days. The numbers of the shear line days, as well as the torrential rain days during June-July are on insignificant annual increase, and its increase rate is one order of magnitude larger than that of the shear line torrential rain days which is basically unchanged in the past 33 years. Earlier than 2000, there are more frequency fluctuations of shear line day, torrential rain day and shear line torrential rain day compared with that after 2000.There are some similar decadal variances in torrential rain days, shear line days and shear line torrential rain days over the Yangtze-Huaihe river region, and those decadal variances of the 3 series are also similar with the decadal variance of precipitation amount over the Yangtze-Huaihe river region in the period of 1981-2007.The shear line torrential rain mostly occur between late June and early July, the meiyu period. The number of shear line torrential rain days during June-July shows 2-3 year period prior to 1995 and no significant period later than 1995.Climatologically, the numbers of shear line torrential day show a 2-4 day period in early-middle June and middle-late July, while it shows no significant period from late June to early July, indicating that shear line torrential rain days maintain a stable frequency during that period, and the precipitation caused by shear line makes up most of the Meiyu precipitation.