近35 年青藏高原雨量和雨日的变化特征

利用青藏高原1971-2005年49个气象台站逐日雨量和雨日资料，分析了青藏高原年、季雨量和雨日变化趋势。结果表明，近35年西藏大部分地区年雨量、雨日呈现显著增加趋势，而青海省大部分地区雨量、雨日却呈减少趋势。夏半年，高原上雨日减少，雨量增加，说明降水越来越集中，降水强度在增加。冬半年。高原上雨日、雨量均在增加。高原夏半年小雨（0．1～4．9mm）雨日减少，雨量增加；小雨（5．0～9．9mm）和中雨的雨日和雨量均呈增加趋势，大雨以上的雨日和雨量均减少。冬半年，青藏高原小雪、中雪、大雪不同量级日数和雪日的平均雪量均呈增加趋势：暴雪日和雪量变化均不明显。

Climatic Characteristics of Rainfall and Rainy Days during the Last 35 Year s over the Qinghai- Xizang Plateau

By using the daily rainy days and rainfall data of 49 stations in 1971-2005 over the Qinghai-Xizang Plateau,the trends of the annual and seasonal rainfall and rainy days are analyzed.The result shows that the trend of the annual rainfall and rainy days increases remarkably in most parts of Tibet,but the trend decreases in most parts of Qinghai.The rainy days are decreasing and the rainfall is increasing in summer half year over the Qinghai-Xizang Plateau,which indicates that the rainfall is centralizing more and more and the rainy intensity has increased.In winter half year,the rainy days and rainfall increase.In summer half year,the spit(0.1-4.9 mm) rainy days decrease,but the rainfall increases.And the rainy days and rainfall of spit and moderate rain(5.0-9.9 mm) increase,the rainy days and rainfall of heavy rain decrease.In winter half year,the rainy days and rainfall of light snow,moderate snow and heavy snow have an increasing trend,while the trend of storm is not obvious.