长江源区和黄河源区降水量变化分析

利用长江源区和黄河源区22个气象站1961—2010年的逐日降水量资料,基于正态分布和Gamma分布,从概率角度讨论了两个源区的年、季节和日降水量的变化特征。结果表明：黄河源区年平均降水量和标准差均大于长江源区,近年来长江源区降水量明显增多,两者之间差异减小。两个源区年内降水量分布很不均匀,长江源区降水量大多集中于夏季,年际间丰枯差异显著;黄河源区降水量集中于夏季,年际变率随时间变化减小,降水稳定性增加;两个源区的日降水量以小雨为主,极端日降水量可达暴雨程度,近年来,随着形状参数和尺度参数的增大,日降水量概率分布有偏度和陡峭度减小的趋势,导致日降水量有所增大,进而影响到极端日降水量,使其有增大趋势。

Analysis of precipitation variation in source regions of Yangtze River and Yellow River

Daily precipitation data from 22 meteorological stations in the source regions of the Yangtze River and the Yellow River from 1961 to 2010 were used to investigate the characteristics of annual,seasonal,and daily variations of precipitation over these regions from the perspective of probability,based on normal and gamma distributions.The results show that both the annual average precipitation and the standard deviation in the source region of the Yellow River were greater than those in the source region of the Yangtze River.Precipitation in the source region of the Yangtze River has increased significantly in recent years,resulting in the reduction of the difference between the two source regions.Intra-annual precipitation distribution was very uneven in the two source regions.Precipitation in the source region of the Yangtze River was mostly concentrated in the summer,and there was an obvious wet and dry difference in inter-annual precipitation.Precipitation in the source region of the Yellow River was concentrated in the summer,and the inter-annual variability decreased while the precipitation stability increased over time.Daily precipitation in the two source regions was mainly drizzle.However,the extreme daily precipitation could reach the level of storm rain.In recent years,with the increase of the shape and scale parameters,there has been a decreasing trend in the skewness and steepness of the probability distribution of daily precipitation,resulting in an increase in daily precipitation and an increasing trend of extreme daily precipitation.