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Transionospheric Radiolink - Near real-time TEC maps

Near real-time vertical Total Electron Content (TEC) map for, provided by Ionosphere Monitoring and Prediction Center (IMPC), DLR.

The service "Transionospheric Radiolink - Near real-time TEC maps" aims to provide maps of the Total Electron Content (TEC) no more than 5 minutes after observation (near real-time). Supplementary materials are measurements from ionosondes (URSI parameters), height of maximum electron density in the F2 layer (hmF2). The Smoothed Sunspot Number (SSN) and the solar flux density from the entire solar disk at 10.7 cm (F10.7) are solar parameters contributing to this service. They are proportional to the level of ionisation in the ionosphere and therefore commonly used for TEC models.

This service addresses the needs of trans-ionospheric radio links users. This includes primarily Global Navigation Satellite System (GNSS) users and service providers, using GNSS single frequency services (e.g. EGNOS users and typical GNSS mass market users), GNSS multi-frequency services (e.g. aeronautical systems, geodetic users, Real Time Kinematik) and users of satellite data communications (e.g. Search and Rescue, Air Traffic, etc.) and other space-based services affected by the ionosphere (e.g. radars, altimetry, radioastronomy, etc.).

The URSI parameters include hmF2 and ITEC derived from true-height analysis of ionosonde data. This data is valuable for the comparison and validation against GPS TEC measurements.

This service is implemented through a combination of products, tools and alerts which can be found through the following tabs along with expert support provided by the teams constituting the SWE Network. Should you require further guidance in the use of this service, or have specific questions about any aspects of the service presented here, don't hesitate to contact the Helpdesk.

The service is implemented through the following set of assets:

  • Ionosphere Monitoring and Prediction Center (IMPC) provided by the German Aerospace Center (DLR);
  • Real-Time Ionosphere Monitor (RTIM) provided by the Norwegian Mapping Authority (NMA);
  • European Ionosonde Service (EIS) provided by National Observatory of Athens (NOA);
  • Service Supporting Resource Exploitation System Operators (RESOSS) provided by he Tromsø Geophysical Observatory (UiT) and the Norwegian Mapping Authority (NMA);
  • Ionospheric Scintillation Monitoring (ISM) developed by Collecte Localisation Satellites (CLS) and IEEA;
  • Swarm Utilisation Analysis (SUA) provided by GFZ German Research Centre for Geosciences;
  • ESA/ESOC Ionosphere Monitoring Facility, IONMON.

This service page is curated by the ESC Ionospheric Weather.  For further information, please contact SSCC Help-desk


The Total Electron Content (TEC) is defined as the integral of the electron density along the ray path between satellite and receiver. Thus, TEC provides the number of electrons per square metre. The most frequently used unit is 1TECU = 1x1016 electrons / m2.

TEC measurements are available since the middle of the 1950s. Various techniques have been applied. The basic three methods using radio techniques for deriving TEC are:

  • Faraday rotation,
  • Group delay and
  • differential carrier phase.
Commonly, radio signal transmission from various satellites is used to derive TEC. TEC data can be derived from satellite radio beacon operations, but the data base is limited due to its geographic coverage. Today, GNSS measurements provide an excellent data coverage for the generation of TEC maps. But also measurements from ionospheric sounders (e.g. ionosondes), making routine measurements of the bottom side ionosphere, can be used to derive TEC and generate maps. In this case, models are required to consider the top side ionosphere (cf. EIS - Near Real Time TEC, below).


TEC measurements can be used by system designers or operators to make a correction for the time delay effects of the ionosphere on their system. Continuous measurements of carefully calibrated TEC are today required for many applications, e.g.

  • users of satellites for precise time transfer
  • advanced ranging systems
  • radio astronomers, who require a knowledge of the effects of the ionosphere on their measurement accuracy
Furthermore, TEC measurements essentially contribute to the investigation of the physics in the upper atmosphere and ionosphere.

Key Products

Near Real Time TEC maps

TEC maps present the vertical integral of the electron density. Near real-time TEC maps are very soon after completion of the measurements. This services provides different types of TEC maps:

  • IMPC - Near Real Time TEC maps are provided with global coverage and for the European region. They are provided with 5 minutes latency and 15 minutes temporal resolution. Both products differ in the applied background model. A dedicated European TEC background model allows a higher quality TEC product for the European region. Each TEC map is provided along with a TEC error map.
  • RTIM - Near Real Time TEC maps are high resolution TEC maps for the high-latitude region around the Scandinavian countries (50°N – 80°N, 10°W – 40°E). Since the data coverage is high, no TEC background model is necessary. The temporal resolution is 5 minutes and the spatial resolution is 1° x 1° in latitude and longitude. The quality of the RTIM - TEC maps is presented by the Grid Ionospheric Vertical Error (GIVE) values. The GIVE is an upper bound on 99% of the TEC error.
  • ISM - Near Real Time TEC maps have a global coverage. Their temporal resolution is 1 hour.
  • EIS - Near Real Time TEC maps are derived from ionosonde measurements. Four different maps are produced for the European region each 15 min of the hour: the map of the integrated electron density from 90km to hmF2 (bottomside TEC), the map of the integrated electron density from hmF2 to the transition height (topside TEC), the map of the integrated electron density from the transition height to 20,000km (Plasmaspheric TEC) and the map of the integrated electron density from 90km to20,000 km (TEC). The mapped area extends from -10 °W to 40 °E in longitude and from 34 °N to 60 °N in latitude, and the spatial resolution of the maps is 1°x1°. The product is based on the 3D electron density grids that are calculated using TaD model (Belehaki et al., 2012; Kutiev et al., 2012) in DIAS system. The maps are made available with a latency of 30 min in both ASCII and PNG formats.

URSI parameters

URSI parameters are derived from ionosonde observations. They help interpreting the ionospheric conditions. This service provides URSI parameters, which are currently provided by the EIS service.

Ionospheric Disturbances

For most users, the degree of perturbation of the ionosphere is of high interest. Currently, this service provides Rate Of change of TEC Index (ROTI) observations. ROTI is related to scintillations. Key products are

  • ROTI maps are provided by IMPC for Europe and by RTIM for FennoScandinavia.
  • Within the RESOSS application, ROTI at the ground is provided. This product shows ROTI for a specified ground receiver location, which is easier to apply for users.
  • Additionally, the SUA activity provides ROT along the flight paths' of the three Swarm satellites.


For further information, please contact SSCC Help-desk

The following products are associated with this service:

Total Electron Content Maps, Nowcast

Vertical Total Electron Content Map
  • TEC map (Europe), current
  • TEC map (Global), current
  • VTEC maps (northern Europe)
  • IONMON TEC maps
  • TEC and Err(TEC) nowcast modelled maps
  • TEC and Err(TEC) nowcast modelled values at a given location
  • Near real-time TEC maps for the European region
  • Swarm Total Electron Content (TEC)
3D Electron Density Grids
  • Swarm electron density (Ne)

URSI ionospheric parameter values, Nowcast

URSI Ionospheric Parameters
  • Nowcast European maps of foF2

Scintillation, Nowcast

Scintillation Indices and Parameters
  • S4 maps (northern Europe)
  • σφ maps (northern Europe)
  • Local scintillation indices S4 & σφ Kiruna
  • Local scintillation indices S4 & σφ Neustrelitz
  • Local scintillation indices S4 & σφ Svalbard
  • Local scintillation indices S4 & σφ Tenerife
  • Local scintillation indices S4 & σφ Toulouse
  • S4 and Err(S4) nowcast modelled maps
  • SigmaPhi and Err(SigmaPhi) nowcast modelled maps
  • S4 and Err(S4) nowcast modelled values at a given location
  • SigmaPhi and Err(SigmaPhi) nowcast modelled values at a given location

Riometer, Nowcast

Riometer Data

    Solar Data, Nowcast

    Smoothed Sunspot Number (SSN, R12)
      Solar Microwave Index (F10.7)
        Solar Flares
        • UGraz/KSO Latest Solar flare detections
        • SIDC Latest daily space weather bulletin
        Solar X-ray Flux
        • Proba2/LYRA Rescaled latest data
        Solar EUV Integrated Flux
          Solar UV Flux

            Geomagnetic Storm Indices, Nowcast

            Local External Magnetic Field on Ground
            • Magnetogrammes from North(west) Europe and Greenland
            • Real-time and historic geomagnetic activity plots and data files for geomagnetic surveying (total field)
            • Real-time and historic geomagnetic activity plots and data files for directional drilling (total field, declination and inclination)
            Local Geomagnetic Induced Geoelectric Field
            • Maps for power and pipeline operators
            • Table of modelled GIC
            • Pipe-to-soil voltage (PSV)

            Tools associated with this service:

            The AMDA system provides an archive of planetary, solar wind, Earth magnetosphere and ionosphere mission and ground based products. In addition it supports a range of standard models such as magnetic footprints, magnetic fields, solar wind propagation to planets and probes as well as access to external databases of observations and simulations. A key functionality of the system is its embedded plotting, data mining and cataloguing functionalities which are extremely useful in relation to posteriori analysis.

            SWE Data is a web application that provides access to a wide range of Space Weather related data sources covering the areas of the spacecraft, ionospheric, and ground effects. SWE Data allows the user to access all data contained in the repository providing analysis and visualisation tools from these disparate sources.

            Alerts associated with this service:

            Ionospheric Disturbance Detection

            Alerts for ionospheric disturbances in the European sector


            This section provides links to web pages or resources that are not part of the SSA Space Weather Network or esa.int domain. These sites are not under ESA control and therefore ESA is not responsible for any of the information or links that you may find there.

            Other European Ionosphere Services

            Reference documents