GPM IMERG卫星降水数据在青海的适用性评价

Applicability evaluation of GPM IMERG satellite precipitation data in Qinghai

为了探究GPM IMERG卫星降水数据在青海的适用性,本文基于青海31个气象站点2001—2017年获取的降水观测数据,应用相关系数(CC)、均方根误差(RMSE)和相对偏差(RB)对GPM IMERG卫星降水数据在青海的适用性进行了评价。结果表明:(1)在年、月尺度上,GPM IMERG卫星降水数据与实测降水数据拥有较高的一致性(CC_(年)=0.741,CC_(月)=0.768),月尺度的RMSE为30.878 mm,且GPM IMERG降水量总体呈低估现象(RB=-17.77%)。(2)在空间尺度上,GPM IMERG卫星降水数据与单一站点降水数据的精度验证具有明显的空间差异性,GPM IMERG卫星降水数据在青海南部地区的精度明显高于北部地区,但大部分气象站点的GPM IMERG降水量呈低估现象,高估现象主要集中在柴达木盆地。(3)随着海拔高度和局部地势起伏的变化,GPM IMERG卫星降水数据和实测降水数据具有相同的变化趋势;随着海拔梯度的增加,GPM IMERG对降水的监测逐渐由偏低转向偏高。(4)基于K9ppen气候分区进行精度评价的结果表明,GPM IMERG在Bwk(干旱荒漠-寒冷气候)和ET(寒冷苔原气候)气候类型区的精度最高,在Dwc(冬冷干-夏冷气候)气候类型区的精度次之,在Bsk(干旱草原-寒冷气候)和Dwb(冬冷干-夏暖气候)气候类型区的精度最低。

In order to explore the applicability of GPM IMERG satellite precipitation data in Qinghai,the applicability is evaluated by using correlation coefficient(CC),root mean square error(RMSE)and relative bias(RB)based on the precipitation observation data from 31 meteorological stations in the area from 2001 to 2017.The results are as follows:(1)At annual and monthly scales,GPM IMERG satellite precipitation data has high consistency with ground station precipitation data measured from station(CC_(year)=0.741,CC_(month)=0.768).The monthly RMSE is 30.878 mm.GPM IMERG precipitation is generally underestimated(RB=-17.77%).(2)At spatial scale,there is a significant spatial difference in accuracy verification between GPM IMERG satellite precipitation data and pre cipitation data from a single station.The accuracy of GPM IMERG satellite precipitation data in the southern Qinghai is significantly higher than that in the northern region.However,the precipitation of GPM IMERG at most stations is underestimated,while overestimation mainly concentrated in the Qaidam Basin.(3)As the altitude and precipitation data measured by terrain fluctuation change,GPM IMERG satellite precipitation data and precipitation data measured by meteorological stations have the same variation trend.As the altitude gradient increases,the monitoring of precipitation by GPM IMERG gradually shifts from low to high.(4)Based on the Köppen climate classification,the accuracy evaluation results show that GPM IMERG has the highest accuracy in the Bwk(arid desert-cold climate)and ET(cold tundra climate)climate type areas,followed by the Dwc(dry winter-cold summer climate)climate type areas,and the lowest accuracy in the Bsk(dry grassland-cold climate)and Dwb(dry winter-warm summer climate)climate.