Space Science Institute

Geomagnetic Perturbations Related to a Variety of Phenomena in the Near-earth Space Environment Induce Electric Fields at the Earth S Surface. These "geoelectric" Fields in Turn Drive Potentially Damaging Geomagnetically Induced Currents (GIC) in Technological Infrastructure Such as Railroads Pipelines Submarine Cables and Power Grids. the Spatio-temporal Specification of Geoelectric Fields Is Needed to Improve Forecasts of Gic and the Combination of Ground Conductivity Measurements and the Time Rate of Change of the Magnetic Field (DB/DT) Can Be Used to Estimate the Geoelectric Field. Pulsations or Waves at the Lower End of the Ultra Low Frequency (ULF) Band in the Coupled Magnetosphere-ionosphere (m-i) Generate Periodic Ground Magnetic Perturbations and DB/DT That Have Been Linked to Geoelectric Fields and Gic. a Better Understanding of the Role of Ulf Waves in Generating Geoelectric Fields Is Thus Needed to Improve Gic Models and Forecasting Capabilities. ..we Propose a Coordinated Investigation Using Satellite Measurements Coherent Scatter Radars (superdarn) Ground Magnetometers Magneto-telluric Surveys and Geoelectric Field Measurements to Address the Over-arching Science Question "how Do Ulf Waves in the M-i System Couple to Geoelectric Field Variations Relevant to Gic?" With Sub-questions "what Are the Spatial/temporal Scales of DB/DT and Geoelectric Fields Associated With Different Ulf Wave Modes? What Combinations of Ulf Wave Properties Driving Conditions and Local Ground Conductivities Are Associated With the Largest DB/DT and Geoelectric Fields?" by Examining How Ulf Waves Couple Through the M-i System to Ground DB/DT This Study Addresses the High-level Decadal Survey Goal 2 "determine the Dynamics and Coupling of Earth S Magnetosphere Ionosphere and Atmosphere and Their Response to Solar and Terrestrial Inputs " Is Consistent With the Nasa Heliophysics Division Strategic Objective to "understand the Sun and Its Interactions With the Earth and the Solar System Including Space Weather" (nasa Heliophysics Roadmap) and Complements Efforts by the Nasa LWS Institute Gic Group. ..we Will Address the Science Questions Through a Combination of (1) Estimates of Ulf Geolectric Fields Obtained From a Meta-analysis of Previous Ulf Wave Studies and Magneto-telluric Impedance Measurements (2) Global Measurements of Ulf Wave Properties Used to Obtain Geoelectric Fields in Detailed Case Studies (3) Statistical Analysis of Co-located Ground Magnetic and Geoelectric Field Measurements. the Pi Is Qualified for This Study Due to (1) Research Contributions That Demonstrate Ulf Wave Expertise and Ability to Explore New Scientific Ideas That Will Impact the Ulf Wave and Gic Research Fields and (2) Current Leadership Activities That Demonstrate Ability to Develop Ulf Wave Themes Lead Community in New Directions and Mentor Junior Researchers. ..this Investigation Is Timely as It Uses Several Recently Available Datasets to Provide New Constraints on Ulf Wave Impacts on Geoelectric Fields/gic. Through Ulf Wave Expertise and Current Leadership Activities (e.g. Gem Ulf Wave Focus Group) the Pi Is Well-positioned to Communicate New Results to Both the Ulf Wave and Gic Modeling Research Groups Fostering Cross-discussion Between These Communities and Focusing Future Modeling/observation Efforts on Ulf Wave Modes Most Likely to Generate Significant Gic. .