4D tropospheric tomography using GPS estimated delays

Retrieval of 4D fields of the tropospheric distribution of water vapor using GPS measurements is an additional and attractive use of the Global Positioning System. Stochastic GPS tomography has successfully been used in ionospheric studies and the authors describe a similar approach for tropospheric studies. They present initial results, comparisons with other sources of data and some insight on the system requirements and its resolution capabilities. GPS data were processed using the GIPSY-OASIS II (GOA II) software to extract the slant extra delays due to the wet troposphere. The inverse problem is then solved using the in-house software LOTTOS, which has been developed to yield the 4D refractivity field. Data were tracked at the local permanent network in Kilauea, Hawaii, during February 1997. This technique can potentially be used to monitor in a near real time basis the status of the troposphere using a dense local network of receivers