Regional PWV Estimation Using GPS and NCEP CFSv2

Site-specific surface meteorological data are essential to derive the precipitable water vapor (PWV) using ground-based GPS. However, many GPS networks lack co-located sensors which can be used to obtain these meteorological variables. This paper proposes a method, which involves the interpolation of surface pressure and temperature fields obtained from the National Centers for Environmental Prediction (NCEP) Climate Forecast System Version 2 (CFSv2) 6-hourly products to derive these site-specific meteorological data. In addition, the significance of ellipsoid-MSL height bias correction on the meteorological data was tested by considering mean sea surface height (MSSH) in our estimation. Based on Hong Kong Satellite Positioning Reference Station Network (SatRef), the method is tested and the results indicate that, the MSSH has a significant influence on the interpolated surface pressure, while less influence on the interpolated surface temperature. The average RMSE of the interpolated surface pressure and temperature are 1.61hPa and 1.93K after the MSSH correction, respectively. The estimated PWV yields an RMSE of 2.76mm, demonstrating the effectiveness of the proposed method.