The Total Electron Content product was designed to specify vertical and slant TEC in near real time. This product has evolved over time. Originally an experimental US-TEC product with a spatial extent as the Continental United States (CONUS), to an operational product covering North America, and after Feb 2025, a global operational GloTEC product.
The Space Weather Prediction Center (SWPC) provides real-time total electron content as part of its mandate to provide real-time monitoring and forecasting of solar and geophysical events (see also SWPC model page). NCEI is the U.S. National Archive for the US-TEC (2004-2023) and GloTEC (2025-present) products output.
NCEI provides online access to the TEC data products between Jan 2016 and Nov 2023 (US-TEC) and after Feb 2025 (GloTEC). For earlier dates, data request should be submitted to ncei.spaceweather@noaa.gov.
Files and Documentation
- US-TEC Product Format Readme
- USTEC Product - 2003 Halloween Storm Event (historic notable event from before the established archive)
- USTEC Products Oct 2004-Dec 2015 (data available on request via email to ncei.spaceweather@noaa.gov )
- USTEC Products 2016
- USTEC Products 2017
- USTEC Products 2018
- USTEC Products 2019
- USTEC Products 2020
- USTEC Products 2021
- USTEC Products 2022
- USTEC Products 2023
- GloTEC Products 2025
US-TEC Product Details
The US-TEC product was designed to specify vertical and slant TEC over the Continental US (CONUS) in near real time. The slant path data files specify the line-of-sight electron content to the GPS satellites in view at the time. The product uses a Kalman Filter data assimilation model, that is driven by data from ground-based Global Positioning System (GPS) dual frequency receivers. The primary data stream comes from the Maritime and Nationwide Differential GPS (M/NDGPS) real-time network of stations operated by the US Coast Guard (USCG), and is provided to the Space Weather Prediction Center by the National Geodetic Survey’s (NGS) Continuously Operating Reference Stations (CORS) network. Secondary data streams are provided by the GPS/Met network (meteorological application of GPS data) and the Real Time IGS (International GNSS Service) network. In 2023, there were about 80 CORS, 30 GPS/Met, and 15 IGS stations ingested into the model.
Note that TEC values in regions outside of the CONUS have no data and should be treated with caution.
GloTEC Product Details
The Global Total Electron Content (GloTEC) model is a global 3D data assimilation system that uses a Gauss-Markov Kalman Filter to optimally estimate electron density in the ionosphere. The system ingests slant Total Electron Content (sTEC) from the ground-based GNSS receivers as well as space-based Radio Occultation (RO) sTEC from the COSMIC-2/FORMOSAT-7 constellation. International Reference Ionosphere 2016 (IRI-2016) driven by the real-time F10.7 index is used as a background model both as an a-prior state and to propagate the state forward between assimilation. Ground-based GNSS observations used in GloTEC come from several data providers. The default GloTEC horizontal grid resolution is 2.5° in latitude and 5° in longitude with a variable vertical grid resolution (20km from 80-450km, and then an increasing grid spacing from 450km to 8500km). The default GloTEC horizontal grid resolution is 2.5° in latitude and 5° in longitude with a variable vertical grid resolution (20km from 80-450km, and then an increasing grid spacing from 450km to 8500km).
Partners
US-TEC evolved through a collaboration between the Space Weather Prediction Center (SWPC), the National Geodetic Survey (NGS), NCEI, and the Global Systems Division (GSD).
