NOAA Continuously Operating Reference Stations (CORS) Network

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 NCN data set enables users to attain centimeter-level positioning for points of interest and can be used to measure crustal motion, moisture content for the lower atmosphere, enhance water level observations and total electron content (TEC) in the upper atmosphere.

Use Constraints: Use liability: NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose.

Access Constraints:

Distribution liability: NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, 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.

Data from the NCN is distributed from two sources:

1. NGS itself at an hourly or daily cadence, in accordance with Partner distribution and,

2. NESDIS/NCEI archive via CLASS infrastructure. NCN data is harvested daily, but not distributed until 30 days hence.

The data includes daily GPS or GNSS observables along with computed geometric coordinates (Latitude, Longitude, Ellipsoid Height) for each station.

Information on the details of the data sets is available at: https://geodesy.noaa.gov/CORS/

Use at your own risk

While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA 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. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

https://geodesy.noaa.gov/CORS/

https://geodesy.noaa.gov/corsdata/

https://geodesy.noaa.gov/UFCORS/

https://noaa-cors-pds.s3.amazonaws.com/index.html

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While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA 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. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

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The GPS or GNSS data collected at these stations are made available to the public by NGS in Receiver INdependent EXchange (RINEX) format. The data include observation, meteorological (where available), navigation/ephemeris, station logs and NGS coordinate files for the stations. Most data are available within 1 hour from when they were recorded at the remote site, and the rest have a delay of 24 hours.

Receiver and Antenna is at least dual frequency, receiving L1 and L2 signals.

Receiver tracks at least ten satellites above 0 degrees.

Receiver provides L1 and L2 full wavelength carrier phase.

Receiver must have be accepted as suitable for inclusion into International GNSS Service or IGS network

Antenna code, antenna model + radome, must be permitted by NGS for inclusion into the NCN.

The carrier phase observations are accurate to a few centimeters, once biases have been removed.

For further information, see https://geodesy.noaa.gov/CORS/data.shtml

+/- 2.0 cm

+/- 4.0 cm

The carrier phase observations are accurate to a few centimeters, once biases have been removed.

For further information, see https://geodesy.noaa.gov/CORS/data.shtml

The National Geodetic Survey, or NGS, publishes coordinates for NCN in several reference frames. This includes the current global reference frame from the International GNSS Service, or IGS, and with respect to the National Spatial Reference System, NSRS, realizations of the North American Datum of 1983, NAD 83, as defined by NGS. Reference frames are updated periodically as according to policy: https://geodesy.noaa.gov/INFO/Policy/files/042011_CORS_Coordinate_Policy.pdf

To become part of the NOAA CORS Network (NCN), each station must meet NGS' station criteria standards and maintain its integrity. Data is quality controlled by NGS before it is distributed to the public. In addition, NGS publishes position and velocity values for each CORS in both the global reference frame and in the National Spatial Reference System. More information can be found at https://geodesy.noaa.gov/PUBS_LIB/CORS_guidelines.pdf

NGS defines thresholds during processing.

Data distribution happens from two data centers: NOAA/NGS (operational) and NESDIS/NCEI (archive) at different cadences.

The NCN operational data is harvested by NGS at an hourly or daily cadence, according to how the collaborating Partners distributes data. Data is available at NGS online operations hourly or daily.

The long term archive is distributed by NESDIS/NCEI. This data is made available to the public on the 31st prior to the current day. This 30 day delay is to allow collaborating partners to assure full data integrity and quantity before archive.

NGS makes every effort to archive missing data.

NCN RINEX archive data is held and staged at the National Centers for Environmental Information (NCEI) for 30 days prior to archive. NGS is allowed to make changes to that data holding at NCEI within the 30 day window. NCEI transfers data for archive to NOAA's Comprehensive Large Array-data Stewardship System (CLASS) after the 30 day period. NGS is the authority on the NCN data set, and can replace or remove archived files at its discretion.

NCN data is processed by NGS operations at an hourly or daily cadence, dependent a particular stations' retrieval frequency. Hourly data is deleted from Partners are deleted two days after daily file is created. Hourly data from NGS-owned stations are kept.

NCN data is harvested daily by NESDIS/NCEI, and then archived after a 30-day period, and distributed via the NCEI archive at the Comprehensive Large Array-data Stewardship System (CLASS).