1960—2017年黄土高原昼夜降水变化特征

为了探究黄土高原气候暖干化背景下的昼夜降水变化规律,利用黄土高原55个气象观测站1960—2017年逐日降水数据,使用线性拟合和空间分析法研究了年际及雨季(5—10月)降水量、降水日数、降水强度及夜雨率等降水指标的变化特征。结果表明:(1)黄土高原历年和雨季的昼夜降水量、降水日数均呈下降趋势,降水强度则呈上升趋势。历年降水量和降水日数下降幅度高于雨季,降水强度上升幅度低于雨季。(2)黄土高原地区雨季昼夜降水指标的空间格局差异明显。雨季降水量和降水强度自东南向西北递减,昼降水日数呈西南和东北偏多、西北偏少,夜降水日数呈西南偏多、西北偏少的空间特征。(3)黄土高原历年及雨季的平均夜降水率分别为50.44%,50.34%。晋豫交界及六盘山以西区域夜雨率高于50%; 陕西西部及中北部、内蒙包头至呼和浩特、祁连山以东等区域夜雨率呈上升趋势,山西中部及东北部、宁夏银川至内蒙鄂托克旗等区域下降趋势明显。综上,黄土高原地区未有明显的夜雨现象。

Characteristics of Change in Diurnal Precipitation in the Loess Plateau During 1960-2017

In order to explore the diurnal precipitation variation in the Loess Plateau under the background of climate warming and drying,we used the daily precipitation data of 55 meteorological stations from 1960 to 2017 to analyze the variation characteristics of inter-annual and rainy season(May-October)precipitation,precipitation days,precipitation intensity and night rain rate by using linear fitting and spatial analysis method.The results show that the precipitation and precipitation days of diurnal precipitation over the annual and rainy season decreased in the Loess Plateau,while the precipitation intensity showed an upward trend;the decrease range of precipitation and precipitation days over the years were higher than those in rainy season,and higher at night than those in daytime;the increase range of precipitation intensity over the years was lower than that in rainy season,and higher at night than that in daytime;the spatial pattern of diurnal precipitation indices in rainy season in Loess Plateau were obviously different;in rainy season,precipitation and precipitation intensity decreased from southeast to northwest;the number of precipitation days was more in southwest and northeast,less in northwest,and the number of night precipitation days was more in southwest and less in northwest;the average night precipitation rate over the years and in the rainy season were 50.44%and 50.34%,respectively;the rate of night rain was higher than 50%in the area of Shanxi-Henan border and the west of Liupan Mountain;it was rising in the west and the north central part of Shaanxi,Baotou to Hohhot and the east of Qilianshan Mountain,and declining in the middle and northeast of Shanxi,Yinchuan to Etuoke Banner of Inner Mongolia.In conclusion,there is no obvious night rain phenomenon in the Loess Plateau.