Accuracy Assessment of Applying ERA-Interim Reanalysis Data toCalculate Ground-based GPS/PWV over China

Objective Meteorological parameters are needed when ground-based GPS is used for the detection ofPWV(precipitable water vapor).However,a large amount of GPS data has not been sufficiently usedbecause of the lack of related meteorological data.In this paper,the methods and feasibility of deri-ving meteorological parameters from ERA-Interim reanalysis data and calculating GPS/PWV with theextracted parameters in China are assessed.The atmospheric pressure,temperature and relative hu-midity derived from ERA-Interim are compared with meteorological observation data at 24meteoro-logical stations from 2006to 2007,and the GPS/PWV calculated from the two data sets are also con-trasted.Results are as follows:① Atmospheric pressure derived from upper-air reanalysis data,tem-perature and relative humidity derived from surface reanalysis data,has relatively high precision.② The reanalysis parameters and meteorological observation data comparisons at 24stations show amean bias of 0.08hpa and a RMSD of 0.85hpa with atmospheric pressure,a mean bias of 0.05Kanda RMSD of 2.45Kwith temperature,a mean bias of 2.82%and a RMSD of 14.75% with relative hu-midity.③ The ERA-Interim reanalysis data is more reliable in the east of China than in the west.Theprecision of temperature and relative humidity data show seasonal variation.④ As compared withGPS/PWV calculated by the meteorological observation data,the GPS/PWV calculated by the ERA-Interim data give a mean difference of less than 0.5mm and a RMSD of less than 1mm.