Determination and assessment of GNSS-derived precipitable water vapor in Indonesia using Ina-CORS

Abstract

This work is the first attempt to investigate the accuracy and reliability of the Ina-CORS (Indonesian Continuously Operating Reference Stations) for meteorological applications. We used the standard procedures to determine and assess the precipitable water vapor (PWV) obtained from the Global Navigation Satellite System (GNSS) measurements. The GNSS-derived zenith tropospheric delay (ZTD) was estimated using the GAMIT software, and it was then converted to PWV using surface pressure measurements and the water vapor weighted mean temperature. The results were compared against those derived from the fifth generation of the European Centre for Medium-Range Weather Forecasts (ECMWF ERA5) data.Comparisons against the ECMWF ERA5 data reveal the following findings. Values for the mean bias and root mean square deviation (RMSD) of the GNSS-derived ZTD over the period 2011–2020 are −6.6 mm and 14.1 mm, respectively, representing the total percentage error of about 0.4%. The total errors from the surface pressure measurements and the calculations of water vapor weighted mean temperature introduce errors to the PWV values with the magnitude less than 1 mm. The GNSS-derived PWV values over Indonesia are comparable with those derived from the ECMWF ERA5 data. The mean bias and RMSD of PWV values are −0.60 mm and 2.59 mm, respectively. In addition, spatio-temporal variations of the GNSS-derived PWV can capture the main atmospheric features that are consistent with the other results deduced from long-term rainfall data. One of the features is the annual and semiannual cycles of PWV that largely correspond to the annual migration of the Asian-Australian monsoon system. Based on these results, we can conclude that the Ina-CORS is capable enough for accurate monitoring of the Indonesian weather and climate variations.