基于最优分割法的年降水阶段划分--以合肥站降水为例

Division of Precipitation Stage Based on Optimal Dissection Method:A Case Study in Hefei Station

基于合肥站1953—2019年的日降水量资料,采用最优分割法对合肥站多年平均日降水量序列进行阶段初步划分,结合降水阶段的大气环流背景分析,识别了合肥的降水阶段。结果表明:合肥全年降水有6个阶段,分别是冬季少雨阶段(11月29日至次年2月12日),早春雨阶段(2月13日至4月4日),春夏雨阶段(4月5日至6月19日),梅雨季(6月20日至7月12日),盛夏雨季(7月13日至9月4日)和秋雨阶段(9月5日至11月28日)。梅雨季和盛夏雨季是其主雨季,日降水量均值分别为6.9、4.3 mm,对应夏季风盛行期和夏季风极盛期;冬季少雨阶段和秋雨阶段降水最少,日降水量均值分别为1.1、2.0 mm,对应冬季风极盛期和夏冬季风转换交替期;早春雨阶段和春夏雨阶段的日降水量均值分别为2.3、3.2 mm,对应冬夏季风转换交替期和夏季风影响期。合肥降水受季风气候影响显著,各降水阶段对应着相对稳定的天气气候背景。

Based on daily precipitation data of Hefei station from 1953 to 2019,this paper divides stages of precipitation in Hefei preliminarily by the optimal dissection method,and identifies the precipitation stages ultimately according to the general atmospheric circulation of precipitation stages.The results show that six stages can be identified in Hefei,including the stage of dry season in winter(November 29 to February 12 next year),the stage of rainy season in early spring(February 13 to April 4),the stage of rainy season in spring and early summer(April 5 to June 19),the stage of plum rainy season(June 20 to July 12),the stage of rainy season in midsummer(July 13 to September 4)and the stage of rainy season in autumn(September 5 to November 28).The plum rainy season and the rainy season in midsummer are the two main rainy seasons,of which the average daily precipitation is 6.9 mm and 4.3 mm respectively,and the corresponding atmospheric circulation is predominant and flourishing periods of summer monsoon respectively;the stage of dry season in winter and the stage of rainy season in autumn are periods with rare precipitation,of which average daily precipitation is 1.1 mm and 2.0 mm respectively,and the corresponding atmospheric circulation is flourishing periods of winter monsoon and transition period of summer to winter monsoon respectively;and the remaining two periods are the stage of rainy season in early spring and the stage of rainy season in spring&early summer,of which the average daily precipitation is 2.3 mm and 3.2 mm respectively,and the corresponding atmospheric circulation is transition period of winter to summer monsoon and initial period of summer monsoon respectively.Precipitation in Hefei is strongly affected by the monsoon,and the atmospheric circulation of each stage is relatively stable.