Validation of GPS derived integrated water vapor (IWV) of the atmosphere on the Georgia’s territory

Abstract

The delay in radio signals from the Global Navigation Satellite System (GNSS) is proportional to the integrated water vapor (IWV) in the atmosphere above the GNSS site. In this paper some peculiarities of atmospheric water vapor distribution derived from 7 GPS located on Georgia’s territory are presented. We calculate ZPD data these GPS and converted into IWV using observed surf-ace pressure and mean atmospheric column temperature obtained from the surface meteorological stations of Georgia’s NHMS. The same variables have been obtained from the ECMWF ERA interim reanalyzes – for two years 2014-2015 period and compared with station obse-rvations. As radiosonde data for Georgia’s stations are not available GPS derived IWV values were compared to the IWV from the ECMWF ERA interim reanalyses with a special focus on the monthly averaged difference (bias) and the standard deviation of daily differences. This comparison shows that the GPS derived IWV values are well suited for the vali-dation of ERA interim reanalyzes of IWV. For most GPS stations, the IWV data agree quite well with the analyzed data indicating that they are both correct at these locations. Larger differences were mainly found in less humid areas during warm periods of year.