2022 CAN Awards

PROJECT: Response of Coupled Magnetosphere-Ionosphere-Thermosphere (MIT) System to Changing Levels of Geomagnetic Activity

Science PI: Amani Reddy, Assistant Professor, UAF

During space weather events, called geomagnetic storms here on Earth, the energy deposited at high latitudes into the Earth’s upper atmosphere can increase by 10- to 20-fold, leading to thermospheric heating and expansion and neutral composition changes. Heating and expansion of the thermosphere drives high-velocity disturbed neutral winds from the polar regions toward the equator. Within minutes of storm commencement, high-latitude electric fields penetrate to low latitudes. The plasmasphere, an inner part of Earth’s magnetosphere, erodes. All of these processes catalyze plasma flows along geomagnetic field lines, coupling the nearly collision-less magnetosphere to the highly collisional ionosphere and thermosphere.

Knowledge of the electron and ion number densities (Ne and Ni) along geomagnetic field lines is required to understand processes such as plasmasphere erosion and refilling, ionospheric outflows, magnetospheric particle precipitation, wave-particle interactions that regulate the response of the coupled magnetosphere-ionosphere-thermosphere (MIT) system and plasmasphere dynamics. Whistler mode waves propagate close to geomagnetic field lines (B0). Therefore, unlike other space- and ground-based methods, the WM radio-sounding method permits electron and ion densities (Ne and Ni) measurements along B0 [Sonwalkar et al., 2011a; 2011b]. These measurements, combined with advanced physics-based model simulations, provide a powerful new approach [Reddy et al., 2018] to determine the underlying processes that play a role in the storm-time dynamics of the highly-coupled MIT system.

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