A global empirical model for mapping zenith wet delays onto precipitable water vapor using GGOS Atmosphere data

Abstract

The importance of water vapor in research of global climate change and weather forecast cannot be over emphasized; therefore substantial efforts have been made in exploring the optimal methods to measure water vapor. It is well-established that with a conversion factor, zenith wet delays can be mapped onto precipitable water vapor (PWV). However, the determination of the exact conversion factor depends heavily on the accurate calculation of a key variable, weighted mean temperature of the troposphere (T _m). As a critical parameter in Global Positioning System (GPS) meteorology, T _m has recently been modeled into a global grid known as GWMT. The GWMT model only requires the location and the day of year to calculate T _m. Despite the advantages that the GWMT model offers, anomalies still exist in oceanic areas due to low sampling resolution. In this study, we refine the GWMT model by incorporating the global T _m grid from Global Geodetic Observing System (GGOS) and obtain an improved model, GWMT-G. The results indicate that the GWMT-G model successfully addresses the anomaly in oceanic areas in the GWMT model and significantly improves the accuracy of T _m in other regions.