黄土高原区不同降水相态的时空变化

以1960~2013年黄土高原区及周边58个气象站的地面逐日降水数据为基础,对黄土高原区不同降水相态的时空分布特征进行了分析,研究表明：黄土高原区雨、雪分界线在35°N附近,以北区域以降雪为主,以南且110°E以西的区域以降雨形态为主。该分界线附近是雨夹雪的多发区。黄土高原区降雨有明显的年际波动,而降雪的波动不是很明显,雨夹雪和雾（露、霜）这几种降水相态年际波动较小且趋势一致。液态降水、降雪呈减少趋势,雪、雨夹雪、雾（露、霜）呈增加趋势。雪、雨夹雪、雾（露、霜）均存在显著的准30 a的振荡周期,此外,这4种降水相态还存在15 a、10~12 a、5 a中小尺度的周期。

Spatial and Temporal Variation of Different Precipitation Type in the Loess Plateau Area

Base on the data of daily precipitation of 58 meteorological stations in Loess Plateau Region, the temporal and spatial variations of different precipitation phases were analyzed in Loess Plateau Region. The results show that line of 35°N is the delimitation boundary of main snow region and rain region; the region to the north of 35°N is the snow region, the region to the south of 35°N and to the east of 110°E is main rain region. Besides, along the 35°N and 110°E, the sleet occurs frequently. The rains in Loess Plateau Area have obvious and different inter-annual fluctuations, but the snow is not very obvious. Except rain and snow, the fluctuation frequencies of sleet, fog (dew, frost) were weak and tend to the same. The station-days of all these recipitation phases (rain sleet fog dew frost) have remarkable 30 a periods. Besides, there were also 5 a, 10 a and quasi 15 a periods to different precipitation phases.