汉江上游汉中区域不同等级降水日数的气候变化特征分析

Climatic Variation Characteristics of Precipitation Days of Different Classes in Hanzhong Region Over the Upper Hanjiang River

利用1981~2020年汉江上游汉中区域11个气象观测站逐日降水资料,采用相关系数、线性趋势及Mann-Kendall检验等方法,分析了近40 a汉江上游汉中区域不同等级降水日数气候变化特征及其与总降水量关系。结果表明:汉中区域总雨日数与小雨日数、中雨日数的均呈现出从中部平川县区向南、北部山区递增的空间分布特征;大雨日数及暴雨数日基本呈现从北向南递增的空间分布规律;总雨日数、小雨日数表现出明显减少趋势,中雨日数、大雨日数和暴雨日数也表现出减少趋势,但是未能通过显著性检验。小雨日数与总雨日数均表现为20世纪80年代初到1991年为偏多时段,90年代初到2017年为偏少时段,之后逐渐增加,大雨日数与中雨日数变化趋势相似,80年代偏多,90年代初期之后偏少,后期又缓慢上升,暴雨日数呈现波动性变化趋势;总雨日数1989年发生了突变,小雨日数的突变年份为1992年,中雨日数、大雨日数和暴雨日数在研究时段内没有发生突变。小雨日数对总雨日数影响最大,总降水量贡献率最主要来源于大雨日数和暴雨日数。

Based on the daily precipitation data of 11 meteorological stations of Hanzhong region over the upper Hanjiang River from 1981 to 2020,the climatic variation characteristics of precipitation days of different classes in Hanzhong region over the upper Hanjiang River in recent 40 years and their relationship with the total precipitation are analyzed by using the methods of correlation coefficient,linear trend and Mann-Kendall test and so on.The results show that the total number of rainy days,the number of light rainy days and the number of moderate rainy days in Hanzhong region all show the spatial distribution characteristics of increasing from Pingchuan County in the central part to the south and north mountain areas;The number of heavy rainy days and storm rainy days basically show the spatial distribution law of increasing from north to south;The total number of rainy days and light rainy days showed an obvious decreasing trend,and the number of moderate rainy days,heavy rainy days and storm rainy days also showed a decreasing trend,but failed to pass the significance test.The number of light rainy days and the total number of rainy days are both more in the period from the early 1980 s to 1991,and less in the period from the early 1990 s to 2017,and then gradually increased.The change trend of the number of heavy rainy days is similar to that of the number of moderate rainy days,which is more in the 1980 s,less in the early 1990 s,and slowly rising in the later period.The number of storm rainy days shows a fluctuating trend;The total number of rainy days had a sudden change in 1989;the light rainy days had a sudden change in 1992,and the number of moderate rainy days,heavy rainy days and storm rainy days had no sudden change in the study period.The number of light rain days has the greatest impact on the total number of rain days,and the contribution rate of total precipitation mainly comes from the number of heavy rain days and storm rainy days.