Station-based water vapor estimation using sparse national GPS network

GPS data processing for water vapor estimation has been to date based on a baseline approach in which data acquired from different stations are processed at a data processing centre using differential GPS techniques. This approach however is limited by the requirement of short distances between GPS tracking stations. This paper is to describe a station-based approach which processes GPS data at different stations independently, taking advantage of widely available high precision GPS orbit and clock data. The method can provide improved flexibility and efficiency for water vapor estimation and is particularly efficient to implement using sparse national GPS network. The paper will describe the methodology of station-based water vapor determination and the obtainable accuracy of the water vapor estimates using data from a geodetic network of continuously operating GPS reference stations in Canada.