HAO Colloquium - Dong Lin, HAO

Multiple-Reflection Modification of Auroral Precipitation and its Effects in Magnetosphere-Ionosphere-Thermosphere Coupling

High-latitude ionospheric conductivity is one fundamental physical parameter that has significant impacts on Magnetosphere-Ionosphere-Thermosphere (M-I-T) coupling. It not only regulates field-aligned currents and high-latitude convection pattern in magnetosphere-ionosphere coupling, but also determines where and how energy and momentum dissipate in the upper atmosphere, and thereby affects the global behavior of the upper atmosphere during magnetically active periods. In this study, we include two kinetic processes in a first principles, coupled magnetosphere, inner magnetosphere, thermosphere and ionosphere (LTR) model. These two processes affect dynamically the magnitude and distribution of ionosphere conductivity, but have not been included together in previous M-I-T system simulations. These two processes are: 1) lower ionospheric microscale Farley-Buneman turbulence (AEH), and 2) Super Thermal Electron Transport (STET) correction that describes more accurately the multiple reflections of electrons from magnetically conjugate regions and wave-driven electron energization. Four LTR simulations for the 2013 St. Patrick’s Day storm event have been carried out: 1) base run without FBT and STET; 2) with just AEH; 3) with just STET; and 4) with both AEH and STET. Preliminary model outputs show that AEH and STET change ionospheric conductivity significantly in regions of large electric fields and strong field-aligned currents by altering the mean energy and number flux of auroral precipitation. This then modifies field-aligned currents and high latitude convection pattern. The effects of this ionospheric conductivity change on Joule heating and ion drag, and thus thermosphere circulation and composition, ionosphere electron densities, will also be presented in this talk.

Date and time: 
Wednesday, February 19, 2020 - 2:00pm to 3:00pm
Captain Mary 2139