Real-Time Sensing Atmospheric Water Vapor Using Precise GPS Orbit and Clock Products

Y. Gao, S. Skone, K. Chen, N. A. Nicholson, R. Muellerschoen

Abstract:	The use of ground-based GPS observations to estimate the amount of Precipitable Water Vapor (PWV) in the troposphere has been extensively investigated. The estimation so far, however, is feasible only in postmission or near real-time (30-minute delay) because of the time required in receiving raw data from all network stations and the complexity of the estimation process. Due to the importance of high temporal resolution in severe weather forecast and operational numerical weather prediction, the key issue of ground-based GPS meteorology is how to derive high-precision Zenith Wet Delay (ZWD) estimate, which is nearly proportional to the vertically integrated water vapor overlying the GPS receiver, from GPS observations with latency as short as possible. This paper describes the concept of absolute zenith troposheric delay (ZTD) estimation and the method of ZTD estimation using real-time precise satellite orbit and clock products. The observation equations and estimation models as well as error mitigation will be presented. Key factors that would affect troposphere estimation will also be addressed including horizontal gradients, mapping function selection, antenna phase center variation, elevation cutoff angle etc. Experiments have been conducted to assess the obtainable accuracy via a comparison with the measurements from a water vapor radiometer. The test results have demonstrated millimeter-accurate PWV estimates which are obtainable in real-time. The potential applications of such real-time ZWD estimation system and aspects that require further attention will also be addressed.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	2343 - 2352
Cite this article:	Gao, Y., Skone, S., Chen, K., Nicholson, N. A., Muellerschoen, R., "Real-Time Sensing Atmospheric Water Vapor Using Precise GPS Orbit and Clock Products," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 2343-2352.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In