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

gpsmet

browse graphicA 30 day time series of integrated precipitable water vapor (IPW) estimated at Boulder, CO and Blacksburg, VA
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 present. 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.
  • Cite this dataset when used as a source: Holub, Kirk L. and Gutman, Seth I. (2016):Ground-Based Global Positioning System (GPS) Meteorology, Version 1.0. NOAA National Centers for Environmental Information (NCEI). doi:10.7289/V5DR2SHD [access date].
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Distribution Formats
  • netCDF-3
Distributor Customer Engagement Branch
DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
1-828-271-4800
ncei.orders@noaa.gov
Dataset Point of Contact Customer Engagement Branch
DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
1-828-271-4800
ncei.orders@noaa.gov
Dataset Point of Contact Kirk Holub
Physical Scientist
DOC/NOAA/OAR/ESRL/GSD/ > Global Systems Division, Earth System Research Laboratory, OAR, NOAA, U.S. Department of Commerce
+1-303-497-6642
Kirk.L.Holub@noaa.gov
Time Period 2002-04-01 to 2016-11-29 (time interval: 30-minute)
Spatial Reference System urn:ogc:def:crs:EPSG::4326
Spatial Bounding Box Coordinates
N: 90.0
S: -90.0
E: 180.0
W: -180.0
Spatial Coverage Map
General Documentation
Processing Documents
Associated Resources
Publication Dates
  • publication: 2002-04-01
  • creation: 2002-04-01
  • lastUpdate: 2016-11-29
Edition 1.0
Data Presentation Form Digital document - digital representation of a primarily textual item (can contain illustrations also)
Dataset Progress Status Complete - production of the data has been completed
Data Update Frequency Not planned
Supplemental Information
The near real-time estimates of IPW have a resolution is 30 minutes. They are based on GPS signal delay estimates and surface pressure and temperature observations.
Purpose The primary uses for the data set are to demonstrate the major aspects of an operational GPS integrated precipitable water vapor (IPW) monitoring system, facilitate assessments of the impact of these data on weather forecasts, assist in the transition of these techniques to operational use, and encourage the use of GPS meteorology for atmospheric research and other applications.
Use Limitations
  • There are no known limitations to the dataset's usability. The system is all-weather; limited only by power at and communications with the CORS sites.
Dataset Citation
  • Cite this dataset when used as a source: Holub, Kirk L. and Gutman, Seth I. (2016):Ground-Based Global Positioning System (GPS) Meteorology, Version 1.0. NOAA National Centers for Environmental Information (NCEI). doi:10.7289/V5DR2SHD [access date].
Cited Authors
  • Holub, Kirk
    DOC/NOAA/OAR/ESRL/GSD/ > Global Systems Division, Earth System Research Laboratory, OAR, NOAA, U.S. Department of Commerce
  • Gutman, Seth
    DOC/NOAA/OAR/ESRL/GSD/ > Global Systems Division, Earth System Research Laboratory, OAR, NOAA, U.S. Department of Commerce
Originators
  • Holub, Kirk
    DOC/NOAA/OAR/ESRL/GSD/ > Global Systems Division, Earth System Research Laboratory, OAR, NOAA, U.S. Department of Commerce
Principal Investigators
  • Gutman, Seth
    DOC/NOAA/OAR/ESRL/GSD/ > Global Systems Division, Earth System Research Laboratory, OAR, NOAA, U.S. Department of Commerce
Publishers
  • DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
Theme keywords Global Change Master Directory (GCMD) Science Keywords
  • Earth Science
  • Atmosphere
  • Atmospheric Water Vapor
  • Precipitable Water
Global Climate Observing System (GCOS) Essential Climate Variables (ECVs)
  • Air Temperature
  • Water Vapour
  • Air Pressure
Data Center keywords Global Change Master Directory (GCMD) Data Center Keywords
  • DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
  • DOC/NOAA/OAR/ESRL/GSD/ > Global Systems Division, Earth System Research Laboratory, OAR, NOAA, U.S. Department of Commerce
Platform keywords Global Change Master Directory (GCMD) Platform Keywords
  • In Situ Land-based Platforms
Instrument keywords Global Change Master Directory (GCMD) Instrument Keywords
  • GPS
  • GNSS RECEIVER
Place keywords Global Change Master Directory (GCMD) Location Keywords
  • Vertical Location
Project keywords Global Change Master Directory (GCMD) Project Keywords
  • GPS/MET > Global Positioning System Meteorology Experiment
Data Resolution keywords Global Change Master Directory (GCMD) Vertical Data Resolution Keywords
  • Point Resolution
Stratum keywords Global Change Master Directory (GCMD) Location Keywords
  • Vertical Location > Troposphere
Use Constraints
  • Cite this dataset when used as a source: Holub, Kirk L. and Gutman, Seth I. (2016):Ground-Based Global Positioning System (GPS) Meteorology, Version 1.0. NOAA National Centers for Environmental Information (NCEI). doi:10.7289/V5DR2SHD [access date].
  • NCEI cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NCEI makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty. NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives.
Fees
  • In most cases, electronic downloads of the data are free, however fees may apply for data certifications, copies of analog materials, and data distribution on physical media.
Lineage information for: dataset
Lineage Statement The purpose of the National Oceanic and Atmospheric Administration's (NOAA) Ground-Based GPS-IPW project (gpsmet) was to: Evaluate the engineering and scientific bases of surface-based GPS meteorology; demonstrate the feasibility and utility of using surface-based GPS observations for improved weather forecasting, climate monitoring, and satellite sensor calibration/validation; transfer this observing system technology to operational use. The Global Systems Division (GSD) Demonstration Branch (DB) (now Global Systems Division [GSD]) established the world's first GPS network dedicated to atmospheric remote sensing in 1994. This project was a collaboration between NOAA Research and several organizations and institutions including: NOAA's National Geodetic Survey (NGS) which manages the network of Continuously Operating Reference Stations (CORS); including some of the GSD/DB GPS-IPW network sites, NOAA's National Data Buoy Center (NDBC), The U.S. Department of Transportation Federal Highway Administration (DOT), The U.S. Coast Guard (USCG) International GPS Service (IGS) which maintains global network of tracking sites; including some of the GSD/DB GPS-IPW network sites, Scripps Institution of Oceanography (SIO) University of Hawaii at Manoa (UHhttp://lumahai.soest.hawaii.edu/Dept/meteorology/index.html), UNAVCO (UNAVCO) The Department of Energy Atmospheric Radiation Measurement (ARM) Program. All processing software and products used or created by the gpsmet processing system reside on GSD systems or at NCEI archives.
Processor
  • DOC/NOAA/OAR/ESRL/GSD/ > Global Systems Division, Earth System Research Laboratory, OAR, NOAA, U.S. Department of Commerce
Processing Steps
  • Estimation of IPW required two components; an estimate of ZTD and observations of the surface pressure and temperature. Estimation of ZTD began the acquiring GPS observation data from a collection of GPS CORS sites. These observations were used as inputs, along with earth orientation parameters (OEP) and internal terrestrial reference frame (ITRF) parameters, by GAMIT to estimate ZTD. Once ZTD had been estimated it separated into two components, wet and dry, using surface meteorological data. In the final step IPW was estimated by applying an empirical mapping parameter to the the estimated wet component.
    Rationale: Estimation of IPW required two components; an estimate of ZTD and observations of the surface pressure and temperature. ZTD cannot be directly observed by the GPS receivers. It must be obtained by processing the GPS observations.
Processing Environment The network is controlled by a software system developed by ESRL/GSD in conjunction with the Scripps Institution of Oceanography (SIO) and the University of Hawaii at Manoa (UH). GPS precise predicted orbits from Scripps Orbit and Permanent Array Center (SOPAC) and data from individual sites (GPS and MET) are continuously downloaded by a server. At the beginning of a processing cycle, several processing nodes download the GPS data and predicted orbits for selected sites from the server. The GAMIT (GPS at MIT [http://www-gpsg.mit.edu/~simon/gtgk]) software package provided by the Massachusetts Institute of Technology (MIT) processes this data and produces Tropospheric Signal Delay (ZTD) values (illustrated below.) These values are then processed with Meteorology data from the sites to produce and Integrated Precipitable Water Values (IPW) which are then distributed to interested parties and made available online. The processing system incorporates an 8 hour sliding window technique, with two processing cycles for each hour starting at 02 and 32 minutes after the hour. Each cycle produces 16 individual IPW for each half hour within the sliding window. As the 8 hour sliding window progresses throughout the day, more IPW are produced for each half hour until that particular half hour is no longer within the sliding window. This produces a possibility of 16 values for each half hour. Within each half hour, two IPW are available, a first guess and median value. The first guess IPW is the first value for the half hour meeting the quality control criteria. The median IPW is the median of all results for that particular half hour. This result can be the median of 1 to 16 values depending upon quality control criteria.
Processing Documents
Source Datasets
  • GPS carrier phase observation
    • GPS carrier phase observation
      GPS observation data
    • Description of Source: GPS carrier phase observations
    • Temporal extent used: 2002-04-01 to 2016-11-29
    • Spatial extent used: N:90 S:90 E:180 W:180
  • surface meteorological observations
    • surface meteorological observations
      surface meteorological observation from ASOS sites
    • Description of Source: Meteorological observations
    • Temporal extent used: gco:nilReason="missing"/ to 2016-11-29
    • Spatial extent used: N:90 S:90 E:180 W:180
Lineage information for: repository
Processing Steps
  • 2015-04-22T00:00:00 - NOAA created the National Centers for Environmental Information (NCEI) by merging NOAA's National Climatic Data Center (NCDC), National Geophysical Data Center (NGDC), and National Oceanographic Data Center (NODC), including the National Coastal Data Development Center (NCDDC), per the Consolidated and Further Continuing Appropriations Act, 2015, Public Law 113-235. NCEI launched publicly on April 22, 2015.
Last Modified: 2018-05-04
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