
The Space Weather Prediction Center is pleased to announce the operational release of improved geoelectric field maps, which use an improved description of Earth conductivity based on empirical magnetotelluric transfer functions (EMTF’s). The EMTF’s are a data product from magnetotelluric surveys and provide a way to represent the effects of 3D Earth conductivity. The new maps will provide a more accurate estimate of the geoelectric field which is the space weather driver of geomagnetically induced currents in the power grid. Note that the coverage area for the maps is limited to locations where MT surveys have been completed, therefore SWPC will continue to provide the previous version of the product based on 1D conductivities until the surveys are completed for all of the CONUS. Please see https://www.swpc.noaa.gov/products/geoelectric-field-1-minute-empirical-emtf-3d-model for the latest maps and additional information.