GPS Water Vapor Estimation Using Surface Meteorological Data from Australian Automatic Weather Stations

Z. Bai, Y. Feng

Abstract:	To estimate atmospheric water vapor from GPS data, surface meteorological observations collected at the GPS sites are required. Ideally a dedicated meteorological sensor is installed together with the GPS antenna. However, this involves additional cost at the level of one-third of the geodetic GPS receiver. To take advantage of the existing GPS tracking networks which are established primarily for surveying, geodesy and navigation applications, it is worthwhile to seek alternative solutions, which either bypasses the needs for surface meteorological data, or uses surface meteorological data from other sources instead. This paper presents a case study of using surface temperature and pressure (T & P) hourly observations from the Australian Automatic Weather Stations (AWS) network for GPS Precipitable Water Vapour (PWV) estimation. The question is whether the AWS surface meteorological data is accurate enough. Therefore, the case study focuses on two issues: first the agreement between the interpolated and observed T and P values, and agreement between the GPS-PWV estimates using the surface meteorological data and the radiosonde PWV results. Different Ordinary Kriging methods have been selected for interpolation of meteorological data. Data analysis with 36 data points from the Victoria region in Australia has demonstrated that the Ordinary Kriging method with Linear Variogram is preferable to pressure interpolation, resulting in an overall standard deviation of 0.40 mbar in pressure or 0.15mm in PWV estimation. The paper also presents the GPS-PWV estimation results against radiosonde PWV results for some stations in order to understand the consistence of GPS-PWV estimates from the closest AWS pressures and temperature. Results have shown that GPS-PWV estimates agree with the Rad-PWV solutions at an average mean difference of 0.66 mm and RMS of 1.92mm for the tested stations. This agreement level is considered very reasonable. The experimental study shows a possible way to develop GPS meteorology and applications with the existing meteorological data network. This could save significant costs in installation of GPS-Met sensors.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	1742 - 1749
Cite this article:	Bai, Z., Feng, Y., "GPS Water Vapor Estimation Using Surface Meteorological Data from Australian Automatic Weather Stations," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 1742-1749.
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