A new strategy for real-time integrated water vapor determination in WADGPS networks

A major issue in many applications of CPS is the real-time estimation of th e Zenith Tropospheric Delays (ZTD). Several authors have developed strategi es that estimate ZTD, with a latency of one hour or more in order to comput e Integrated Water Vapor (IWV), using local measurements of surface pressur e, or to assimilate ZTD into Numerical Weather Predicition. (NWP) models. T hese strategies require that data from a regional CPS network be processed in near real-time, using precise IGS orbits and partial orbit relaxation. R ecently it has been shown that in Wide Area Differential CPS (WADGPS) netwo rks of several hundred kilometers across, double-differenced carrier phase ambiguities can be computed on-the-fly, using a real-time tomographic model of the ionosphere obtained from the same CPS data. In this work we show ho w ambiguity resolution can help determine in real-time the ZTD for a WADGPS network user, only 10-20% worse than those of the postprocessed solutions.