基于MSWEP的祁连山地区降水空间分布特性解析

综合评价了全球性降水数据MSWEP(Multi-Source Weighted-Ensemble Precipitation)在祁连山区的适用性,解析了其在不同时空尺度上的误差特征,采用结合地面雨量资料GSOD(Global Surface Summary of the Day)订正后的MSWEP(Corrected MSWEP, COMSWEP),重点探讨了祁连山地区降水的垂直分布特性。结果表明:(1)MSWEP在日、月、年等尺度上总体低估了研究区域地表降水,对暴雨及以上日降水事件存在比较严重的漏报,在雨季的精度要明显高于旱季;(2)相对于MSWEP,COMSWEP在各种时间尺度上与地表降水更为吻合,对雨季降水和年降水具有较好估计效果,但在旱季仍存在较明显系统偏差;(3)MSWEP和COMSWEP均表明祁连山区多年平均降水量在空间上呈由东至西递减、北坡略高于南坡的总体格局,而在时程上雨季降水主导了全年降水,但在不同分区和时间尺度上,COMSWEP降水量均明显高于MSWEP;(4)MSWEP和COMSWEP均反映祁连山地区东段最大降水高度带在3000 m左右,超过此高度带多年平均降水量变化甚小,而中段和西段多年平均降水量随海拔呈现先增加后降低的趋势,最大降水高度带分别位于4100 m和4500 m左右。

Analysis of spatial distribution characteristics of precipitation in Qilian Mountains Based on MSWEP

The accuracy and performance of MSWEP (Multi-Source Weighted-Ensemble Precipitation) data in the Qilian Mountains is evaluated comprehensively at first in this paper. Then the error characteristics on different spatial and temporal scales are analyzed. Finally, the vertical distribution of precipitation in Qilian Mountains is mainly discussed by COMSWEP (Corrected MSWEP) based on precipitation in Global Surface Summary of the Day(GSOD). The results show that:(1) The precipitations in the study area on daily,monthly,and annual scales are generally underestimated by MSWEP,and there is a serious missed detection of rainstorm events on daily scale,while the accuracy in the rainy season is significantly higher than it in the dry season. (2) COMSWEP performs better than MSWEP does on different time scales,and estimated precipitation pretty well on wet season and on annual scale. But the systematic deviation is still significant in the dry season. (3) Both MSWEP and COMSWEP indicate that overall pattern of multi-year average precipitation in the Qilian Mountains shows a decreasing trend from east to west,while it is slightly higher in the northern slope than it in the southern slope. What''s more,precipitation in the wet season dominates the annual precipitation,and COMSWEP is significantly higher than MSWEP in different subareas and time scales. (4) Both MSWEP and COMSWEP show that maximum precipitation height in the eastern Qilian Mountains is around the elevation of 3000m,and the maximum multi-year precipitation has little change when the altitude exceeds 3000m. The multi-year average precipitation in the central and western Qilian Mountains both show a trend of increasing first and decreasing next when the altitude increases. The maximum precipitation height in central and western Qilian Mountains is located at the elevation of 4100m and 4500m,respectively.