Analysis of GPS RTK performance using external NOAA tropospheric corrections integrated with a multiple reference station approach

For high-accuracy geodetic applications, time-variable tropospheric propagation delay errors limit global positioning system real-time kinematic positioning accuracy. Potential improvements in positioning accuracy are evaluated by using the National Oceanic and Atmospheric Administration (NOAA) real-time tropospheric corrections (herein called NOAA model) within a multiple reference station network approach. The results are compared with those for modified Hopfield tropospheric model corrections, for six scenarios in three geographical regions in the U.S. National Geodetic Survey network of Continuously Operating Reference Stations, for baseline lengths of 60~150 km. Analyses are conducted at rover locations for relatively humid days, and misclosures for various double difference observations are computed; these observations include each frequency (L1 and L2) and three linear combinations wide lane, ionosphere free (IF), and geometry free]. The effectiveness of the network approach is demonstrated, with overall performance improvements of 15 and 19%, using the modified Hopfield and the NOAA model, respectively. The IF linear combination, a measure of tropospheric and orbital errors, shows a 3% improvement for the NOAA model compared with the modified Hopfield model.