The National Geodetic Survey (NGS), an office of NOAA's National Ocean Service, manages a network of Continuously Operating Reference Stations (CORS) that provide Global Navigation Satellite System (GNSS) data consisting of carrier phase and code range measurements in support of three dimensional positioning, meteorology, space weather, and geophysical applications throughout the United States, its territories, and a few foreign countries. This is called the NOAA CORS Network (NCN) Surveyors, GIS users, engineers, scientists, and the public at large that collect GPS or GNSS data can use NOAA's CORS data to improve the precision of their positions. CORS enhanced post-processed coordinates approach a few centimeters relative to the National Spatial Reference System, both horizontally and vertically. The NCN network is a multi-purpose cooperative endeavor involving government, academic, and private organizations. The sites are independently owned and operated. Each agency shares their data with NGS, and NGS in turn analyzes and distributes the data free of charge. As of February 2025, the NCN provides data from approximately 2,000 active sites. NCN data holdings to include decommissioned stations, comes to a total of 2,908 sites. These sites are contributed by over 230 different organizations, and the network continues to expand. The DOI referenced is for the archived NCN data holdings.

The National Geodetic Survey (NGS), an office of NOAA's National Ocean Service, manages a network of Continuously Operating Reference Stations (CORS) that provide Global Navigation Satellite System (GNSS) data consisting of carrier phase and code range measurements in support of three dimensional positioning, meteorology, space weather, and geophysical applications throughout the United States, its territories, and a few foreign countries. Surveyors, GIS users, engineers, scientists, and the public at large that collect GPS or GNSS data can use CORS data to improve the precision of their positions. CORS enhanced post-processed coordinates approach a few centimeters relative to the National Spatial Reference System, both horizontally and vertically. The CORS network is a multi-purpose cooperative endeavor involving government, academic, and private organizations. The sites are independently owned and operated. Each agency shares their data with NGS, and NGS in turn analyzes and distributes the data free of charge. As of August 2016, the CORS network provides data from more than 1,950 active sites. CORS data holdings to include decommissioned stations, comes to a total of 2,674 sites. These sites are contributed by over 230 different organizations, and the network continues to expand.

The data set consists of an Excel file containing the supporting data for the following publication:

Lambert, A., Huang, J., Courtier, N., & Pavlic, G. (2020). Constraints on secular geocenter velocity from absolute gravity observations in central North America: Implications for global melting rates. J. Geophys. Res., in prep.

The Excel data file comprises four sheets:

Sheet 1: Annual absolute gravity observations at six sites (1995-2010) and two sites (2002-2010) showing site names, observation time in decimal years, gravity values and standard errors in microGal (1 microGal = 10 nm/s2), site reference gravity values, instruments used, observers names and site co-ordinates.

Sheet 2: Daily GPS heights at five sites (1996/7-2010) and one site (2003-2010) showing site names, observation time in decimal years, heights and standard deviations in meters, and site co-ordinates.

Sheet 3: Daily GPS heights at ten sites (2002-2010) used with data from two sites in sheet 2 to calculate vertical velocities at two absolute gravity sites (sheet 4) where no continuous GPS was available. Site co-ordinates are given in sheet 4.

Sheet 4: Long-term height trends (vertical velocities) are estimated for the two sites lacking continuous GPS by using a 2-D adaptive Gaussian interpolation function, with a half-width defined as the distance to the nearest GPS site. The absolute gravity drop data were processed using the Micro-g LaCoste "g8" software.

The GPS data were processed with the NRCan Precise Point Positioning PPP 1.05 software (Héroux and Kouba, 2001). For each site, daily positions were computed using ionosphere-free combinations of un-differenced pseudo-range and phase observations, with satellite orbits and clocks fixed to the International GNSS Service (IGS) precise products, absolute phase-center calibrations for the GPS and satellite antennas (Schmid et al., 2007), gridded Vienna Mapping Functions (VMF1, Boehm et al., 2006) for the troposphere model, and solid earth and ocean tide corrections. The GPS post-processing was originally carried out in support of Mazzotti et al. (2011).References:

Boehm, J., Werl, B., & Schuh, H. (2006). Troposphere mapping functions for GPS and very long baseline interferometry from European Centre for Median-Range Weather Forecast operational analysis data. J. Geophys. Res., 111, B02406. https://doi.org/10.1029/2005JB003629

Héroux, P., & Kouba, J. (2001). GPS Precise Point Positioning using IGS orbit products. Phys. Chem. Earth (A), 26, 573-578. https://doi.org/10.1016/S1464-1895(01)00103-X

Mazzotti, S., Lambert, A., Henton, J., James, T.S., & Courtier, N. (2011). Absolute gravity calibration of GPS velocities and glacial isostatic adjustment in mid-continent North America. Geophys. Res. Lett., 38, L24311. https://doi.org/10.1029/2011GL049846

Schmid, R., Steigenberger, P., Gendt, G., Ge, M., & Rothacher, M. (2007). Generation of a consistent absolute phase center correction model for GPS receiver and satellite antennas. J. Geod., 81 (12) 781-798. https://doi.org/10.1007/s00190-007-0148-yData Sources and Open Data Policy

Absolute gravity data source: Geological Survey of Canada.

GPS data sources: Canadian Active Control System (CACS) data from Canadian Geodetic Survey’s Geodetic Data Products web site, NASA Crustal Dynamics Data Information System (CDDIS), and U.S. National Geodetic Survey, Continually Operating Reference Stations (CORS) data download site.

Use of Canadian Geodetic Survey products and data is subject to the

Open Government Licence - Canada

© Her Majesty the Queen in Right of Canada, as represented by the Minister of Natural Resources, 2020

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.

This dataset consists of Level II weather radar data collected from Next-Generation Radar (NEXRAD) stations located in the contiguous United States, Alaska, Hawaii, U.S. territories and at military base sites. NEXRAD is a network of 160 high-resolution Doppler weather radars operated by the NOAA National Weather Service (NWS), the Federal Aviation Administration (FAA), and the U.S. Air Force (USAF). Doppler radars detect atmospheric precipitation and winds, which allow scientists to track and anticipate weather events, such as rain, ice pellets, snow, hail, and tornadoes, as well as some non-weather objects like birds and insects. NEXRAD stations use the Weather Surveillance Radar - 1988, Doppler (WSR-88D) system. This is a 10 cm wavelength (S-Band) radar that operates at a frequency between 2,700 and 3,000 MHz. The radar system operates in two basic modes: a slow-scanning Clear Air Mode (Mode B) for analyzing air movements when there is little or no precipitation activity in the area, and a Precipitation Mode (Mode A) with a faster scan for tracking active weather. The two modes employ nine Volume Coverage Patterns (VCPs) to adequately sample the atmosphere based on weather conditions. A VCP is a series of 360 degree sweeps of the antenna at pre-determined elevation angles and pulse repetition frequencies completed in a specified period of time. The radar scan times 4.5, 5, 6 or 10 minutes depending on the selected VCP. The NEXRAD products are divided into multiple data processing levels. The lower Level II data contain the three meteorological base data quantities at original resolution: reflectivity, mean radial velocity, and spectrum width. With the advent of dual polarization beginning in 2011, additional base products of differential reflectivity, correlation coefficient and differential phase are available. Level II data are recorded at all NWS and most USAF and FAA WSR-88D sites. From the Level II quantities, computer processing generates numerous meteorological analysis Level 3 products. NEXRAD data are acquired by the NOAA National Centers for Environmental Information (NCEI) for archiving and dissemination to users. Data coverage varies by station and ranges from June 1991 to 1 day from present. Most stations began observing in the mid-1990s, and most period of records are continuous.