Ground-Based Global Positioning System (GPS) Meteorology Integrated Precipitable Water Vapor (IPW)

The Ground-Based Global Positioning System (GPS) Meteorology Integrated Precipitable Water Vapor (IPW) data set measures atmospheric water vapor using ground-based GPS receivers. The data contain observations from several hundred locations around the globe every 30 minutes from 2002-05-01 to 2016-11-28. However, most locations lie within the continental United States. The data set was formed in response to the need for improved moisture observations to support weather forecasting, climate monitoring, and research. The data set contains total precipitable water estimates, GPS total signal delay, GPS hydrostatic signal delay, GPS wet signal delay, surface temperature, surface pressure, mean-weighted surface temperature, and the wet delay mapping function. The GPS-IPW network processes data from both NOAA and other agency CORS (Continuously Operating Reference Sites) sites. All sites are equipped with a GPS receiver and many are equipped with a surface meteorological instrumentation package. GPS satellite observation are combined with GPS satellite orbit and earth orientation parameters to estimate GPS signal delay (Zenith Total Delay -- ZTD). Signal delays are then combined with surface meteorological information are used to estimate total precipitable water. For sites without surface meteorology sensors, data from nearby ASOS (Automated Surface Observing System) systems were used. Data set variables and their resolution: total precipitable water; 0.001 m, GPS total signal delay; 0.001m, GPS hydrostatic signal delay; 0.001m, GPS wet signal delay; 0.001m, surface temperature; 0.1 K, surface pressure; 0.1 hpa, mean-weighted surface temperature; 0.1 K, wet delay mapping function; 0.1 (dimensionless). Late updated in November 2016 with no plans for updating at this time due to funding.