Global positioning system as a passive integrated atmospheric water vapor sensing device

Abstract

Since the conception of the Global Positioning System (GPS) its applications have grown to provide not only a navigation, but also a geodetic, and more recently a meteorological tool. This latter application has become termed GPS Meteorology. Atmospheric research in GPS initially centered around the premise that the atmosphere was a nuisance parameter (NP). To obtain the highest precisions (particularly in height) this NP has to be modeled, or estimated, in addition to the geodetic parameters. One of the most successful techniques for dealing with this NP has been to stochastically estimate the NP using a Kalman filter. As a by-product to the precise geodetic parameters obtained, tropospheric wet delays (the NP) can also be output. These tropospheric wet delays (TWD) can be related to integrated precipitable water vapor (IPWV) through the simplified equation: TWD equals k(DOT)IPWV. The dimensionless value of k is dependent on the weighted mean temperature of the atmosphere and can be predicted from surface temperature alone (but typically ranges from 6.0 to 6.5). The expansion of the International GPS Geodynamics Service (IGS) network provides the possibility of near-continuous measurements of IPWV anywhere on the Earth by using GPS as a passive remote sensing tool. Such a possibility provides applications for numerical weather prediction (NWP) models and climate and global change research. This paper outlines the current status of atmospheric research in GPS. A project aimed at validating the use of GPS for meteorology at Nottingham is discussed using observations from ground-based water vapor radiometers (WVRs) for validation.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.