Articles | Volume 10, issue 6
https://doi.org/10.5194/amt-10-2045-2017
https://doi.org/10.5194/amt-10-2045-2017
Research article
 | 
07 Jun 2017
Research article |  | 07 Jun 2017

A new voxel-based model for the determination of atmospheric weighted mean temperature in GPS atmospheric sounding

Changyong He, Suqin Wu, Xiaoming Wang, Andong Hu, Qianxin Wang, and Kefei Zhang

Abstract. The Global Positioning System (GPS) is a powerful atmospheric observing system for determining precipitable water vapour (PWV). In the detection of PWV using GPS, the atmospheric weighted mean temperature (Tm) is a crucial parameter for the conversion of zenith tropospheric delay (ZTD) to PWV since the quality of PWV is affected by the accuracy of Tm. In this study, an improved voxel-based Tm model, named GWMT-D, was developed using global reanalysis data over a 4-year period from 2010 to 2013 provided by the United States National Centers for Environmental Prediction (NCEP). The performance of GWMT-D was assessed against three existing empirical Tm models – GTm-III, GWMT-IV, and GTm_N – using different data sources in 2014 – the NCEP reanalysis data, surface Tm data provided by Global Geodetic Observing System and radiosonde measurements. The results show that the new GWMT-D model outperforms 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 a practical alternative Tm determination method in real-time GPS-PWV remote sensing systems.

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Short summary
Atmospheric weighted mean temperature (Tm) is a key parameter in precipitable water vapour (PWV) detection using GPS technique. This paper develops a new voxel-based empirical Tm model, which takes into consideration the lapse rate and diurnal variations of Tm. The theoretical RMS error of PWV resulting from the new model is generally less than 0.8 m over the globe. Therefore, it can be used as an alternative Tm determination method in the real-time GPS-based water vapour detection system.