1961—2013年青海湖南部地区降水变化特征分析

为了全面认识青海湖流域气候变化时空特征，深化了解近几十年青藏高原地区气候显著变化背景，青海湖南部地区降水量时间分布与量级变化的特征，弥补对青海湖流域及其周边区域气候变化动态过程认识不足的现状，针对该区域降水量变化问题展开研究。主要利用1961—2013年青海湖南部地区5个气象站逐日及月降水量历史资料，通过线性回归、滑动平均法，分析了青海湖南部地区近53年季、年降水量变化特征及不同降水等级降水日数，并用Mann-Kendall检验降水突变特征。结果表明：青海湖南部地区年降水总体呈微弱增加趋势，增长率为4.42 mm/10 a，主要来自于春、夏、冬季降水量增加的贡献。青海湖南部地区降水除秋季减小趋势外，春、夏、冬季降水均呈增加趋势，夏季降水增加较为明显，降水量的四季变幅表现为夏季>秋季>春季>冬季。夏半年雨量和雨强呈增大趋势，且小雨雨日减小，中雨雨日和雨量增加；而冬半年小雪雪日减小，小雪强度增大。不同量级降水中，中雨雨日与雨量增多、小雨雨日、雨量与雨强均有减少。降水突变检验表明，青海湖南部地区年平均降水出现2次突变，分别为1976年和2004年，1976年突变前后年平均降水相差158.4 mm，由多雨期转为少雨期；而2004年突变则表现为从少雨期到多雨期，突变前后年平均值相差95.5 mm。

Precipitation Patterns During 1961-2013 in the Area of Southern Qinghai Lake.

The study aims to fully understand the spatial-temporal pattern of climate change around of Qinghai Lake, furthermore, to reduce the deficiency in understanding the dynamic process of climate change in the area of Qinghai Lake basin and its surrounding areas under the condition of warming in Qinghai-Tibet Plateau. Daily and monthly rainfall data from 1961 to 2013 at five weather stations in the south region of Qinghai Lake were used in this paper, annual and seasonal precipitation data, as well as the precipitation days in different levels were analyzed by linear regression and moving average method. We also tested the mutation of precipitation by Mann-Kendall method. The results showed that the annual rainfall had a weak increasing trend with a growth rate of 4.42 mm per decade in the studied area in 1961-2013, it was mainly contributed by the precipitation trend in summer, spring and autumn. The tendency of precipitation showed a clear increase in spring, summer and winter except autumn, and precipitation increase in summer was more obvious. The most wide rainfall amplitude appeared in summer, and then in autumn, spring and winter as a sequence. The amount and intensity of rainfall tended to increase in the summer half year, with a decrease trend of light rain days and an increase trend of both days and amount of moderate rain. However, in the winter half year, snow days of light snow declined but the intensity increased. Our analysis indicated that among the different levels of precipitation, there was an increased trend of days and amount of moderate rain, while there was a decreased trend of light rain days, amount and intensity. Precipitation mutation test indicated that two mutations occurred in 1976 and 2004 for average annual rainfall, it experienced an obvious change from rainy period into dry period in 1976 with a difference of average annual rainfall of 158.4 mm, in contrast, the precipitation showed a change from dry to rainy after 2004 mutation with a difference of 95.5 mm.