Strategies for estimating tropospheric delays with GPS

Until recently, the tropospheric zenith delay (TZD) was considered a nuisance parameter of the GPS observation model. However, as the requirements of the weather forecasting community have become better understood, the possible use of TZDs in weather forecasting has been recognized. There are a number of strategies available to process GPS data and produce TZDs. The complexity of some of these strategies can be significant and may even be prohibitive for non-GPS specialists. With suitable infrastructure and precise GPS products however, the complex strategies can be simplified for efficient production of TZDs. The Geodetic Survey Division (GSD) of Natural Resources Canada (NRCan) supports a GPS tracking station and communication infrastructure and computes GPS satellite products suitable for TZD estimation. This paper describes the GPS products, and different approaches, for TZD recovery and compares them in terms of accuracy, availability and operational merits.