祁连山区北坡降水的时空分布及近期变化

Temporal-spatial Distributions and Recent Changes of Precipitation in the Northern Slopes of the Qilian Mountains

以石羊河、黑河、疏勒河三条流域降水资料,分析祁连山区北坡东、中、西部年降水时空分布特征及山区近40a与平原近50a来的正负距平变化规律。

Analysis of temporal-spatial distributions of annual precipitation in northern slopes of the Qilian Mountains indicates that the annual precipitation has a relationship with altitude expressed by a non-linear equation, that is, Y = A+BIln(X), where X is altitude (m), Y is precipitation (mm), and A and B are constants. It also indicates that the annual precipitation increases with altitude, and the annual precipitation decreases from east to west of the mountains. However, changes of precipitation with altitude are not identical. Two zones, one of which lies at 2 000 m a.s.l. and another is at above 4 000 m a.s.l., have higher increase rates of precipitation. Analysis of recent changes in annual precipitation shows that there are a positive anomaly period and a negative anomaly period in the mountainous areas in recent 40 years, while two positive and two negative anomaly periods in the piedmont plain areas in recent 50 years.