青海地区ERA5大气可降水量分布特征及性能分析

Analysis of the Distribution Characteristics and Performance of ERA5 Atmospheric Precipitable Water in Qinghai

文章利用2010-2020年ERA5再分析资料比湿和地表气压数据计算得到青海地区大气可降水量及其时空分布特征,并将其与西宁站实测气压、露点温度数据计算得到的西宁大气可降水量进行对比分析。结果表明:青海省水汽分布呈现“南湿北干,东湿西干”特征,在垂直分布中水汽主要分布在500 hPa以下,大气可降水量在青海东部河谷地区存在高值区,西南部唐古拉山区和北部高海拔山区存在低值中心。各季节大气可降水量分布中,夏季大气可降水量最高,冬季最小。大气可降水量年变化和日变化中差别不大,月变化中呈现单峰型分布,7月大气可降水量最大,1月和12月最小。ERA5再分析资料对夏季大气可降水量是低估的,而对冬季大气可降水量则是高估的。通过相关性分析发现,ERA5再分析资料和实测资料分别计算得到的西宁大气可降水量相关系数达0.977,相关性较高,具有较好的一致性特征。

Using the specific humidity and surface pressure data of the ERA5 reanalysis data from 2010 to 2020,this paper calculated the atmospheric precipitable water and its spatiotemporal distribution characteristics in Qinghai Province,and compared it with the atmospheric precipitable water of Xining calculated by the measured pressure and dew point temperature data of Xining Station.The results showed that the distribution of water vapor in Qinghai Province showed a characteristic of“wet in the south and dry in the north,wet in the east and dry in the west”.In the vertical distribution,water vapor was mainly distributed below 500 hPa,and there were high value areas of atmospheric precipitable water in the eastern valley area of Qinghai.There were low value centers in the Tanggula Mountains and in the high-altitude mountains of the north part of Qinghai.In the distribution of atmospheric precipitable water in various seasons,there were the highest precipitable water in summer and the lowest precipitable water in winter.It showed little difference between the annual and daily variations of atmospheric precipitable water,with a single peak distribution in monthly variations.The maximum atmospheric precipitable water is in July,and the minimum is in January and December.ERA5 reanalysis data underestimates atmospheric precipitable water in summer,while overestimates atmospheric precipitable water in winter.The correlation analysis of the atmospheric precipitable water at Xining Station was conducted using ERA5 reanalysis data and measured data,respectively.The correlation coefficient reached 0.977,indicating a high correlation and good consistency.