Precision test and analysis of MERRA-2 vapor products in Qinghai-tibet plateau
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摘要: MERRA-2是当前最新发布的大气再分析资料,其提供的格网水汽产品具有较高的时空分辨率,但尚无文献对MERRA-2水汽产品在青藏高原地区的适用性予以评价. 因此,亟需开展青藏高原地区MERRA-2水汽产品的适用性分析. 根据MERRA-2格网水汽数据和格网点位势数据,建立了青藏高原地区的水汽垂直剖面函数,并利用水汽垂直剖面函数将格网点水汽值插值计算到临近探空站点或全球卫星导航系统(GNSS)站点上,再利用双线性插值法进行水平方向上的水汽插值计算,进行精度分析. 研究表明:高原地区测站间日均偏差(bias)多数分布在2 mm以内,月均偏差均小于1 mm,MERRA-2水汽产品在高原中部和北部精度较高,南部精度较低.Abstract: MERRA-2 is the latest atmospheric reanalysis data, and the grid water vapor products provided by it have high temporal and spatial resolution, but there is still no literature to evaluate the applicability of MERRA-2 water vapor products in Qinghai-Tibet Plateau. It is urgent to carry out the applicability analysis of MERRA-2 water vapor products in this region. In this paper, the water vapor vertical profile function of Qinghai-Tibet Plateau is established by using MERRA-2 grid water vapor data and lattice dot height data, and the water vapor value of lattice dot is calculated to nearby sounding station or the Global Navigation Satellite System (GNSS) station by using water vapor vertical profile function, and then the bilinear interpolation method is used to calculate the water vapor interpolation in horizontal direction. Finally, the accuracy analysis is carried out. The results show that the daily average deviation between stations in the plateau area is mostly within 2 mm, and the monthly average deviation is less than 1 mm. While the accuracy of MERRA-2 water vapor products is higher in the middle and north of the plateau and lower in the south.
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表 1 四个季度的负指数拟合情况
季度 $a$ $b$ 拟合优度R2 RMSE 春季(3~5月) 24.71 0.000 396 9 0.837 7 2.575 夏季(6~8月) 52.27 0.000 376 9 0.898 1 4.063 秋季(9~11月) 26.79 0.000 369 2 0.887 6 3.110 冬季(12~2月) 13.74 0.000 448 5 0.840 8 1.441 表 2 四个并址站GNSS反演可降水量情况
站点 相关系数K 拟合优度R2 RMSE 玉树 0.907 7 0.929 8 1.244 拉萨 0.994 5 0.853 6 3.503 和田 0.983 7 0.939 0 1.812 昌都 0.901 6 0.901 6 1.770 -
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