A new strategy for real‐time integrated water vapor determination in WADGPS Networks

A major issue in many applications of GPS is the real-time estimation of the Zenith Tropospheric Delays (ZTD). Several authors have developed strategies that es- timate ZTD, with a latency of one hour or more in or- der to compute Integrated Water Vapor (IWV), using lo- cal measurements of surface pressure, or to assimilate ZTD into Numerical Weather Predicition (NWP) models. These strategies require that data from a regional GPS network be processed in near real-time, using precise IGS orbits and partial orbit relaxation. Recently it has been shown that in WideAreaDierentialGPS(WADGPS)networksofseveral hundred kilometers across, double-dierenced carrier phase ambiguitiescanbecomputedon-the-fly,usingareal-timeto- mographic model of the ionosphere obtained from the same GPS data. In this work we show how ambiguity resolution can help determine in real-time the ZTD for a WADGPS network user, only 10-20% worse than those of the post- processed solutions.

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