天水市近30年第1场透雨的时空变化特征

为探索天水市春季第1场透雨变化特征，运用1981—2010年天水市境内7个气象站3—5月逐日降水观测资料，对春季第1场透雨的时空变化特征进行分析。结果表明，天水市春季第1场透雨出现时间有着从东南到西北推迟的特征，最早出现时间在3月7日，最迟出现时间在 5月31日。3月出现的第1场透雨大多在15 mm以下，15~20 mm及≥20 mm的第1场透雨均出现在4—5月。近30年第1场透雨出现时间呈偏早趋势，透雨量级呈递减趋势。

Spatial and Temporal Variation Characteristics of the First Saturating Rain of Spring in Recent 30 Years in Tianshui

In order to explore the variation characteristics of the first saturating rain of spring, its spatial and temporal variation was analyzed with the precipitation data during March to May of 7 meteorological stations located in Tianshui from 1981 to 2010. The results showed that the date of the first saturating rain delayed from southeast to northwest in Tianshui. The earliest time was on 7^th March and the latest time was on 31^th May. The precipitation of the first saturating rain in March was below 15 mm, and the saturating rain with the precipitation of 15-20 mm and ≥20 mm appeared during April to May. The trend of the first saturating rain is turning to be earlier and its precipitation amount is decreasing in recent 30 years.