A new voxel-based model for the determination of atmospheric-weighted-mean temperature in GPS atmospheric sounding
Other literature type
(issn: 1867-8548, eissn: 1867-8548)
The Global Positioning System (GPS) has been regarded as a powerful atmospheric observing system for determining precipitable water vapour (PWV) nowadays. One of the most critical variables in PWV remote sensing using GPS technique is the zenith tropospheric delay (ZTD). The conversion from ZTD to PWV requires a good knowledge of the atmospheric-weighted-mean temperature (T<sub>m</sub>) over the station. Thus the quality of PWV is affected by the accuracy of both ZTD and T<sub>m</sub>. In this study, an improved voxel-based T<sub>m</sub> model, named GWMT−D, was developed and validated using global reanalysis data from 2010 to 2014 provided by NCEP-DOE Reanalysis 2 data (NCEP2). The performance of GWMT−D, along with other three selected empirical T<sub>m</sub> models, GTm−III, GWMT−IV and GTm_N, was assessed with reference T<sub>m</sub> derived from different sources – the NCEP2, Global Geodetic Observing System (GGOS) data and radiosonde measurements. The results showed that the new GWMT−D model outperformed all the other three models with a root-mean-square error of less than 5.0 K at different altitudes over the globe. The new GWMT−D model can provide an alternative T<sub>m</sub> determination method in real-time/near real-time GPS-PWV remote sensing system.