The NOAA Forecast Systems Laboratory in Boulder, Colorado, in collaboration with the National Geodetic Survey, U.S. Department of Transportation, and U.S. Coast Guard, has successfully developed techniques to incorporate GPS receivers installed at Nationwide and Maritime Differential GPS (N/DGPS) sites into the backbone of a demonstration network of ground-based GPS meteorology (GPS-Met) observing systems. These sites provide real-time observations of total atmospheric water vapor to weather forecasters and modelers with high reliability under all weather conditions. Assimilation of these observations into research numerical weather prediction (NWP) models has resulted in continuous improvements in short-range moisture and precipitation forecasts (Benjamin et al., 1998; Smith et al., 1999, 2000, 2002; Gutman et al., 2001). Sub-hourly GPS-Met retrievals are now being provided to NOAA operational entities via the National Weather Service Telecommunications Gateway, and assimilation of these data into operational NWP models at the NOAA National Centers for Environmental Prediction are expected to begin shortly. One of the most important results of GPS-Met assessments conducted at FSL is that the impact on forecast accuracy increases as the network of GPS-Met observing systems expands. In recent years, state and local government agencies have started to operate a large number of continuously operating GPS receivers for high accuracy positioning and navigation applications. The GPS data from these sites can usually be made available in near real-time with little effort or expense incurred by the site owner. Nonetheless, their proliferation provides NOAA with an extraordinary opportunity to quickly and cost-effectively densify the GPS-Met network. In this presentation, we will discuss how GPS observations from State Departments of Transportation such as Michigan, Ohio, North Carolina, Louisiana, and Florida are being integrated with observations from GPS-Met backbone sites to improve NOAA weather forecast accuracy to the benefit of improved multi-modal (surface and air) transportation safety in America.

References

Smith, T.L., S.G. Benjamin, B.E. Schwartz, B.E., and S.I. Gutman, 2002. Impact of GPS water vapor data on RUC severe weather forecasts. 21st Conference on Severe Local Storms, paper J5.3 (joint session with the NWP/WAF conference) San Antonio, TX Aug. 12-16.

Gutman, S.I., S.G. Benjamin, 2001. The Role of Ground-Based GPS Meteorological Observations in Numerical Weather Prediction, GPS Solutions, Volume 4, No. 4, pp. 16-24.

Smith, T.L., S.G. Benjamin, B.E. Schwartz, B.E., and S.I. Gutman, 2000. Using GPS-IPW in a 4-D data assimilation system. Earth, Planets and Space, 52, 921-926.

Smith, T.L., S.G Benjamin, B.E. Schwartz, and S.I. Gutman, 1999. Using GPS-IPW in a 4D Data Assimilation System, The International Symposium on GPS Application to Earth Sciences (GPS'99 in Tsukuba), October 18-22, Tsukuba, Ibaraki, Japan.

Benjamin, S., T. Smith, B. Schwartz, S. Gutman, and D. Kim, 1998: Precipitation forecast sensitivity to GPS precipitable water observations combined with GOES using RUC-2. 2nd Symp. on Int. Obs. Sys., AMS, Phoenix.