DescriptionGlobal Positioning System Meteorology (GPS-Met) is a ground-based water vapor observing system involving the measurement of integrated (total column) precipitable water vapor in the atmosphere. The technique, called GPS-IPW, uses GPS radio signal delay measurements to derive Integrated Precipitable Water (IPW) and has several advantages over conventional water vapor observing systems including low cost, high measurement accuracy, all weather operability, and long-term measurement stability. GPS-IPW measurements are compatible with retrievals made by satellites and provide an independent method for calibrating and validating global satellite observations.
GPS-Met was developed and operated by the Earth System Research Laboratory (ESRL)/Global Systems Division (GSD). GSD established the world's first GPS network dedicated to atmospheric remote sensing in 1994 and has produced these data in a pseudo-operational role since 2002. These data have been available in MADIS since June 2001 and the NWS began using the data operationally in 2005.
The GPS-IPW network currently consists of 688 sites, grouped into three categories: NOAA Wind Profilers (4 sites), Other NOAA Sites (67 sites), and Other Agency Sites (617 sites).
Since September 1, 2016, GPS-Met data has been provided by Earth Networks Inc (ENI) and will not be distributed beyond NOAA or be publicly available on the Global Telecommunications System (GTS). Under this contract, the number of sites have been reduced.
Data ScheduleData arrive on a continuous, asynchronous schedule, and the current and previous hour's data are processed every 5 minutes. Data from this feed are stored in hourly MADIS files with observations starting at the top of the hour and ending at 59 minutes into the hour (e.g., the 0000 file covers 0000 - 0059).
Data that arrive after 2 hours following the time of the observation are processed in a "data recovery" mode, where once a day batch processing is performed to reprocess data that are 35 days, 7 days, and 1 day old. These data are available with all communications methods supported by MADIS except for ldm.
VolumeTypical daily volume for all MADIS datasets can be seen here.
RestrictionsData is restricted to NOAA Only access.
Last updated 10 January 2018