Abstract
We use estimates of zenith tropospheric delay from terrestrial Global Positioning System (GPS) stations to validate the wet path-delay measurements from the Jason-2/Ocean Surface Topography Mission (OSTM) Advanced Microwave Radiometer (AMR). We validate the AMR wet path-delay measurements provided in the version “T” Geophysical Data Records (GDRs) and those generated using a recently developed coastal algorithm that will be applied to the version “C” GDRs. The new coastal algorithm reduces the variance of the GPS-AMR differences by as much as 28% within 25 km of land. This algorithm also facilitates open-ocean measurement accuracies as close to land as 15 km (as opposed to 25 km). We perform AMR/GPS comparisons with three different troposphere-mapping functions for the GPS-based estimates: Niell, Global, and Vienna. The choice of mapping function has minimal impact on our results, although the Vienna mapping function provided the smallest variance in the AMR–GPS differences.
Acknowledgements
The research was carried out at the Jet Propulsion Laboratory (JPL), California Institute of Technology, under a contract with the National Aeronautics and Space Administration. We thank Rob deCarvalho for various insightful discussions and the three anonymous reviewers for their input, which improved this manuscript.