Remote sensing of the amount of water vapor along the slant path using the ground-base GPS
应用地基GPS遥感倾斜路径方向大气水汽总量

Remote sensing of the amount of water vapor along the slant path using the ground-base GPS is the basis of getting the three-dimensional distribution (water vapor tomography) of water vapor in the immediate vicinity of the site. The principle of remote sensing of water vapor along the slant path using GPS is described in this paper. First, the nonisotropic component of water vapor in different azimuth above the GPS receiver is calculated using the wet gradient and the post-fit residuals, and then slant path water vapor is recreated. In order to prove the accuracy of GPS observation, water vapor radiometers (WVR) were used to observe together with GPS. Comparison between WVR and GPS observations at different sites and times shows that root-mean-square error is less than 4 mm. Therefore, the slant path water vapor amount can be accurately retrieved using this method, which is suited for nearly real-time remote sensing and detection of the atmosphere. Ground-base GPS measurements of water vapor have the advantage of all-weather continued observations. It is a supplement to traditional water vapor observations and provides accurate continued water vapor data for climate research. It also can provide good initial conditions for numerical weather prediction if using GPS receiver network and improve the accuracy of forecasting.