拉萨5mm以上降水日数与旱涝的关系

The Correlation Analysis between 5mm and over Precipitation Days and Drought/flood in Lhasa

运用Ｚ指数法对拉萨历年汛期（６～９月）的旱涝等级进行划分；并分析了实际日降水量≥５ｍｍ日数、相当日降水量≥５ｍｍ日数与旱涝等级的关系。结果表明：Ｚ指数法所划分的旱涝等级与实际情况吻合；相当日降水量≥５ｍｍ日数不仅对汛期雨水的丰欠具有决定性的作用，而且与旱涝等级有着极好的相关性。

The severity of drought/flood is divided by Z index in flood season in Lhasa, Tibet. Then the correlation between 5mm and over precipitation equivalent days and the drought/flood severity was studied. Results show that the severity which determined by Z index tally with the facts. The 5mm and over precipitation equivalent days not only indicate the precipitatiion in flood season but also express high correlation with drought/flood severity.