Precipitable Water Vapor Estimates in the Australian Region from Ground-Based GPS Observations

Suelynn Choy,Minghai Jia,Yuriy Kuleshov,Ta-Kang Yeh,John Dawson,Chuan-Sheng Wang

doi:10.1155/2015/956481

Abstract

We present a comparison of atmospheric precipitable water vapor (PWV) derived from ground-based global positioning system (GPS) receiver with traditional radiosonde measurement and very long baseline interferometry (VLBI) technique for a five-year period (2008–2012) using Australian GPS stations. These stations were selectively chosen to provide a representative regional distribution of sites while ensuring conventional meteorological observations were available. Good agreement of PWV estimates was found between GPS and VLBI comparison with a mean difference of less than 1 mm and standard deviation of 3.5 mm and a mean difference and standard deviation of 0.1 mm and 4.0 mm, respectively, between GPS and radiosonde measurements. Systematic errors have also been discovered during the course of this study, which highlights the benefit of using GPS as a supplementary atmospheric PWV sensor and calibration system. The selected eight GPS sites sample different climates across Australia covering an area of approximately 30° NS/EW. It has also shown that the magnitude and variation of PWV estimates depend on the amount of moisture in the atmosphere, which is a function of season, topography, and other regional climate conditions.

Highlights

Water vapor is the most abundant greenhouse gas in the atmosphere [1] generating more greenhouse effects on our planet than any other single gas such as carbon dioxide
We present a regional quantitative analysis of precipitable water vapor (PWV) focusing on eight Australian Regional Global satellite navigation systems (GNSS)/global positioning system (GPS) Network (ARGN) stations over a fiveyear period (2008–2012)
In evaluating the intertechnique biases, radiosonde should not in any way be assumed to provide the “truth” as it has been recognized in the literature as having its own systematic bias of about 1.2 mm depending on the types of radiosonde [19, 21, 22, 30, 36, 46]

Summary

Introduction

Water vapor is the most abundant greenhouse gas in the atmosphere [1] generating more greenhouse effects on our planet than any other single gas such as carbon dioxide. Water vapor content makes up only 5% of the air and is highly variable in its distribution; that is, it fluctuates seasonally and regionally. This makes water vapor difficult to measure and observe. Water vapor content is one of the poorest observed atmospheric parameters, both spatially and temporally. Accurate, and consistent observations of the atmospheric water vapor content over extended periods of time are fundamental to provide the initial conditions required for climate models

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Results

Conclusion