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Regional Geoelectric 3D (Empirical EMTF) 
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Regional Geoelectric 1D (Fernberg 2012) 
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NOTE: As of 6/21/2023, this page, the Geoelectric 3D-1D Comparison, which covered only the continental US, has been superseded by a new page, Geoelectric Field Models (US and Canada 1D & 3D EMTF CONUS). The new page presents 1D data for the US and Canada while continuing the 3D EMTF data for CONUS.
This web page enables a side-by-side comparison of geoelectric field maps based on different specifications of the earth conductivity. The maps are synchronized in time so that users can easily compare the models at any time step. Further details of this analysis can be found at https://www.swpc.noaa.gov/products/regional-geoelectric-validation.
The geoelectric field at the surface of the earth indicates how much current will be induced in artificial conductors such as power lines, communication cables, pipelines, and railway lines.
The geoelectric field at the surface of the earth indicates how much current will be induced in artificial conductors such as power lines, communication cables, pipelines, and railway lines. The calculation of the geoelectric field is accomplished by convolving geomagnetic field time series with an Earth conductivity description. In the initial model development, a relatively simple conductivity description was used (Fernberg 2012) and this is shown in the map on the right. More recently, an upgrade of the conductivity description has been possible by using Electromagnetic Transfer Functions published as a data service by the Incorporated Research Institutions for Seismology (IRIS), and results using the EMTF's are shown on the left. The maps are synchronized in time so that users can easily compare the models at any time step. Detailed statistical comparisons will be published soon.
Since EMTF results are not available in all locations, there are some portions of the map on the left that are not modeled with the newer method. Survey work is ongoing and the coverage using the newer method is expected to improve over the next 2-3 years.
The full web page for the EMTF version may be viewed here:
https://www.swpc.noaa.gov/products/geoelectric-field-1-minute-empirical-emtf-3d-model.
The full web page for the original 1D (Fernberg 2012) maps is operational and may be viewed here:
https://www.swpc.noaa.gov/products/geoelectric-field-1-minute
The operational version of the 1D (Fernberg 2012) maps became operational in September 2017.
The experimental version of the 3D (Empirical EMTF) maps were deployed in June 2020 and went operational in September 2020. Incremental improvements are anticipated over the next 2-3 years as more survey data are collected and published.
Please refer to the full web page for the respective models for information about the archive.
https://www.swpc.noaa.gov/products/geoelectric-field-1-minute-empirical-emtf-3d-model.
https://www.swpc.noaa.gov/products/geoelectric-field-1-minute