Accuracy and reliability of tropospheric wet refractivity tomography with GPS, BDS, and GLONASS observations

Tropospheric tomography has been developed as a promising tool with which to model the three-dimensional (3-d) spatio-temporal distribution of water vapour field using Global Positioning System (GPS) observations. With the development of multi-GNSS, the accuracy and reliability of tomography using multi-GNSS observations remains to be verified. The observed multi-GNSS (GPS, GLONASS, and BDS) data, are first used to validate the tomographic results derived from various multi-GNSS combined strategies and compared with radiosonde data. In addition, the top boundary of the tomography area is determined based on the variations of water vapour with altitude derived from the COSMIC RO profiles for the period from 2006 to 2016. Tomography experiments were carried out with the 7-day data from six stations in the CORS Network at Guiyang, China. Numerical results reveal that the use of multi-GNSS data can increase the number of satellite rays used and consequently improve the coverage rate of voxels crossed by rays. Tomographic results also show that multi-GNSS observations can increase the accuracy of 3-d wet refractivity reconstruction but not as well as was expected when using currently available techniques. (C) 2018 COSPAR. Published by Elsevier Ltd. All rights reserved.