GPS STORM - GPS SENSING OF ATMOSPHERIC WATER-VAPOR FOR METEOROLOGY/

Atmospheric water vapor was measured with six Global Positioning Syste m (GPS) receivers for 1 month at sites in Colorado, Kansas, and Oklaho ma. During the time of the experiment, from 7 May to 2 June 1993, the area experienced severe weather. The experiment, called ''GPS/STORM,'' used GPS signals to sense water vapor and tested the accuracy of the method for meteorological applications. Zenith wet delay and precipita ble water (PW) were estimated, relative to Platteville, Colorado, ever y 30 min at five sites. At three of these five sites the authors compa red GPS estimates of PW to water vapor radiometer (WVR) measurements. GPS and WVR estimates agree to 1-2 mm rms. For GPS/STORM site spacing of 500-900 km, high-accuracy GPS satellite orbits are required to esti mate 1-2-mm-level PW. Broadcast orbits do not have sufficient accuracy . It is possible, however, to estimate orbit improvements simultaneous ly with PW. Therefore, it is feasible that future meteorological GPS n etworks provide near-real-time high-resolution PW for weather forecast ing.