疏勒河上游高寒草地生长季降水特征

Precipitation characteristics in alpine grassland in the upper reaches of Shule River during growing season

基于2009—2014年疏勒河上游高寒山区(3400~4200 m)的实测资料,本文以距平百分率、降水集中度(PCD)与集中期(PCP)为主要方法,对高寒草地生长季(5—9月)的降水特征进行了分析。结果表明:生长季降水量为139.3~401.6 mm,距平百分率普遍处于-12.9%~18.8%,降水梯度达21.7 mm·100 m^(-1)(2013—2014年);降水最大月多为6月或7月,二者之和约占生长季降水量的55.7%~60.1%;降水集中度为0.21~0.49,集中期分布在6月下旬至7月;次降水以量级<10 mm、历时<24 h、雨强<0.5 mm·h^(-1)为主;疏勒河上游高寒草地的生长季降水具有年际变率小、垂直变化明显、分配较为集中、小降水事件多的主要特征。

Based on field observation data from alpine region （3400-4200 m） in the upper reaches of Shule River between 2009 and 2014, the precipitation characteristics in alpine grassland during growing season （May-September） were evaluated by the methods of anomaly percentage, precipitation concentration degree （PCD） and precipitation concentration period （PCP） in this paper. The results showed that precipitation during growing season was between 139.3 and 401.6 mm, with the anomaly percentage generally ranging from -12.9% to 18.8%, and the precipitation gradient up to 21.7 mm·100 m^-1 （2013-2014）. The maximum monthly precipitation was mainly concentrated in July or June, and their sum amounted to 55.7%-60.1% of growing season precipitation. The PCD ranged from 0.21 to 0.49 and the PCP occurred in the late June to July. The majority of single precipitation events were characterized by magnitude 〈10 mm, duration 〈24 h, intensity 〈0.5 mm·h^-1. Growing season precipitation in alpine grassland in the upper reaches of Shule River had the characteristics of small interannual variability, obvious vertical variation as well as uneven distribution, and was composed mainly of smallprecipitation events.