GPS estimation of atmospheric water vapour from a moving platform

Measuring water vapour content, and its variability, in the atmosphere is important for meteorological and climatological research. Recently, a technique for the remote sensing of water vapour in the atmosphere using ground-based GPS has been rapidly developed. An estimation accuracy for integrated water vapour content of 1-2 kg/m2has been routinely available from such ground-based GPS networks (Dodson and Baker, Proceedings of the ION National Technical Meeting, Navigation 2000, California, January 21-23). Extending this technique into the sea on a moving platform would be greatly beneficial for meteorological research, such as the calibration of satellite data and the investigation of the sea/air interface as well as forecasting and climate studies. However, whether the water vapour can be separated from the motion of the GPS receiver in the estimation process itself, is still an open question. In this paper, a new method, based on a Kalman filter, has been developed to deal with this problem. The initial experiment shows that the accuracy of estimated tropospheric delay from a moving platform is comparable to that from (static) land based receivers.