Department of Physics and Astronomy Zoom:
Meeting ID: 962 6907 1707
Thursday, April 15, 4:00 pm
Diffuse electron precipitation in
Dr. Dong Lin
High Altitude Observatory, National Center for Atmospheric Research
Auroral precipitation plays an important role in magnetosphere-ionosphere-thermosphere (MIT) coupling by enhancing ionospheric ionization and conductivity at high latitudes. Diffuse electron precipitation refers to scattered electrons from the plasma sheet that are lost in the ionosphere. Diffuse precipitation makes the largest contribution to the total precipitation energy flux and is expected to have substantial impacts on the ionospheric conductance and affect the electrodynamic coupling between the magnetosphere and ionosphere-thermosphere. Kinetic theory and observational analysis also demonstrate that diffuse precipitation is subject to multiple reflection effects, i.e., secondary electrons produced by the primary precipitation are reflected between the north and south hemispheres multiple times before they are fully lost in the atmosphere. In this presentation, I will show simulation results of the newly developed Multiscale Atmosphere-Geospace Environment (MAGE) model developed at the NASA DRIVE Science Center for Geospace Storms (CGS) to understand the role of diffuse electron precipitation in MIT coupling. With controlled numerical experiments, we demonstrate that diffuse electron precipitation plays a critical role in determining the meso-scale location and structure of subauroral polarization streams (SAPS). The multiple reflection effects make diffuse precipitation number flux and energy flux a few times higher than the unmodified precipitation, resulting in a greatly enhanced auroral ionospheric conductance, lower cross polar cap potential, higher total field-aligned currents, and changes in global thermospheric winds and temperature. Therefore, diffuse electron precipitation has both local and global impacts on MIT coupling.
Bio: Dr. Dong Lin is an ASP postdoc working at the High Altitude Observatory of National Center for Atmospheric Research with Dr. Wenbin Wang. His current research interests primarily focus on characterizing the magnetospheric precipitation and its effects in magnetosphere-ionosphere-thermosphere coupling with geospace models. He obtained his PhD Degree from Virginia Tech in 2019, supervised by Professor Wayne Scales. He spent one year in the Physics Department of UNH from 2014 to 2015 as a PhD student.
Meeting ID: 962 6907 1707
Thursday, April 15, 2021 at 4:00pm to 5:00pmVirtual Event