Pointed water vapor radiometer corrections for accurate global positioning system surveying

Abstract

Delay of the Global Positioning System (GPS) signal due to atmospheric water vapor is a major source of error in GPS surveying. Improved vertical accuracy is important for sea level and polar isostasy measurements, geodesy, normal fault motion, subsidence, earthquake studies, air and ground‐based gravimetry, ice dynamics, and volcanology. We conducted a GPS survey using water vapor radiometers (WVRs) pointed toward GPS satellites to correct for azimuthal variations in water vapor. We report 2.6 mm vertical precision on a 50‐km baseline for 19 solution days. Kalman filter or least‐square corrections to the same data do not account for azimuthal distribution of water vapor and are degraded by 70%.