SENSING INTEGRATED WATER-VAPOR ALONG GPS RAY PATHS

We demonstrate sensing of integrated slant-path water vapor (SWV) alon g ray paths between Global Positioning System (GPS) satellites and rec eivers. We use double differencing to remove GPS receiver and satellit e clock errors and 85-cm diameter choke ring antennas to reduce ground -reflected multipath. We compare more than 17,000 GPS and pointed radi ometer double difference observations above 20 degrees elevation and f ind 1.3 mm rms agreement. Potential applications for SWV data include local and regional weather modeling and prediction, correction for sla nt wet delay effects in GPS surveying and orbit determination, and syn thetic aperture radar (SAR) imaging. The method is viable during all w eather conditions.