A Novel Approach for Geoelectric Field Response Scaling Factors Used in Geomagnetic Storm Hazard Assessments

In this work, we describe an approach to characterize the ground response to geomagnetic storm drivers and recalculate the scaling factors that are used in the North American Reliability Corporation (NERC) TPL‐007 geomagnetic disturbance (GMD) standard based on magnetotelluric (MT) survey measurements. The new ground response scaling factors indicate a significantly wider range of ground responses from the one‐dimensional model responses used in the original NERC GMD standards framework. Further, the region Mid‐West area west of the great lakes and North‐East around New England and areas along the Appalachian Mountains appear to be particularly exposed to the geoelectric field hazard under extreme space weather conditions. A more complete validation of MT data in geomagnetically induced currents applications is warranted before usage of the presented results as a basis for possible updates to the NERC GMD standard.