1981—2018年内蒙古不同等级降水时空变化特征

基于1981—2018年内蒙古地区103个地面气象观测站的逐日降水资料,运用趋势分析方法,分析近38 a内蒙古降水量、降水日数和降水强度的时空变化特征。结果表明,不同等级降水量和降水日数呈现弱减少趋势,不同等级降水强度年际变化趋势不明显,但是湿润区的各等级降水年际波动最大,干旱区的中雨强度年际波动明显大于其他气候区。各等级降水对总降水的贡献率从大到小依次为小雨、中雨和大雨,但地区分布不均。各气候区小雨日数贡献率均在80%~90%,并且小雨量占比从内蒙古东北部湿润区到西北部的干旱区逐渐上升。内蒙古各等级降水均呈现自东向西递减的空间分布特征,其中降水量和降水日数的高值区主要分布在东北部地区,降水强度的高值区主要分布在东南部地区。2010年以来,内蒙古东北部和中部偏西地区的小雨等级的降水量和小雨日数减少,小雨等级的降水强度增加;在内蒙古西北部各等级降水量和降水强度均增加,大雨等级的降水量、降水日数和降水强度的增加趋势尤为显著。

Spatiotemporal variations of different precipitation grades in Inner Mongolia from 1981 to 2018

Based on the daily surface precipitation data of 103 meteorological observation stations in Inner Mongolia from 1981 to 2018, the linear trend analysis method was used to analyze spatial and temporal climate characteristics of precipitation, precipitation days and precipitation intensities in Inner Mongolia. Results show that:the precipitation and number of precipitation days of all grades show weak decreasing trends, and the interannual variations of precipitation intensity of each grade was not significant. However, the interannual fluctuations of precipitation of each grade in the humid region is obvious, and the interannual fluctuations of moderate-rain intensity in arid region are significantly greater than that in other climatic areas. The average contribution of each grade of precipitation was light rain > moderate rain > heavy rain, but the regional distribution is uneven. The contribution of light rain days in each climatic area is about 80%-90%, and the proportion of light rain is gradually increased from the humid area in Northeast Inner Mongolia to the arid area in Northwest Inner Mongolia. The spatial distributions of all precipitation grades show a spatial distribution characteristic of decreasing from east to west in Inner Mongolia. The high-value areas of precipitation and precipitation days are mainly distributed in the northeast region, and the high-value areasof precipitation intensity are mainly distributed in the southeast region.Since 2010, the light rain amount and number of light rain days in the northeastern and central west of Inner Mongolia have decreased, while the light rain intensity showed an opposite pattern.In the northwest of Inner Mongolia, the precipitation and intensity of all grades have increased, and the increaseing in precipitation, precipitation days and precipitation intensity of heavy rain were particularly significant.