Monitoring Precipitable Water Vapor in Real-Time using Kinematic GPS Precise Point Positioning in Thailand

Abstract

The Global Navigation Satellite System (GNSS) in meteorology known as GNSS-Meteorology is an alternative way to estimate the PWV values, which is fewer data processing load and cost-effective. In the last two decades, several studies have shown that the estimated PWV values derived from ground-based GNSS receivers are nearly proportional to the amount of PWV from the meteorological instruments. Moreover, it has the advantages in high spatio-temporal resolution. In this study, Precise Point Positioning (PPP) technique was used to process the GNSS observation data. The CLK91 real-time orbit and clock products generated to the broadcast ephemeris based on the International GNSS Service (IGS) network were adopted in the data processing step. In order to accurately transform the zenith tropospheric delay (ZTD) into the PWV, the meteorological data and the local mean tropospheric temperature model (Tm) were evaluated for this study. The results showed that the different ZTD values of most stations, about 80% of the real-time epoch solution, were within 20 mm.