摘要
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 trop- osphere （Tin）. AS a critical parameter in Global Positioning System （GPS） meteorology, Tm 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 Tm. 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 Tm 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 Tm in other regions.
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.
基金
supported by the National Natural Science Foundation of China (Grant Nos. 41174012, 41274022)
the National High Technology Research and Development Program of China (Grant No. 2013AA122502)
the Open Foundation of Key Laboratory of Precise Engineering and Industry Surveying of National Administration of Surveying, Mapping and Geoinformation (Grant Nos. PF2012-14, PF2013-12)
