MLT Asymmetries in the Magnetospheric Wave Distribution and Their Effect on Ionospheric Conductivity and Global Transport

Friday, 19 December 2014: 2:28 PM
Richard M Thorne1, Wen Li2, Jacob Bortnik3, Binbin Ni3, Vania Jordanova4, Craig Kletzing5, William S Kurth5, George B Hospodarsky6 and Vassilis Angelopoulos3, (1)UCLA, Atmospheric and Oceanic Sciences, Los Angeles, CA, United States, (2)UCLA, Los Angeles, CA, United States, (3)University of California Los Angeles, Los Angeles, CA, United States, (4)Los Alamos National Laboratory, Los Alamos, NM, United States, (5)Univ. of Iowa, Iowa City, IA, United States, (6)Univ Iowa, Iowa City, IA, United States
Diffuse auroral precipitation is the major source of ionospheric conductivity at high latitudes, and the resulting global distribution of enhanced conductivity affects the penetration of magnetospheric electric fields and plasma transport into the inner magnetosphere. Recent work has demonstrated that diffuse auroral precipitation is caused by resonant scattering of plasma sheet electrons due to a combination of both electrostatic electron cyclotron harmonic waves and electromagnetic whistler mode chorus emissions. Each class of wave is excited, predominantly on the dawn side of the magnetosphere, following the convective injection and gradient drifting of plasma sheet electrons into the inner magnetosphere. During geomagnetically active periods, the resultant electron scattering can approach the limit of strong diffusion, and the timescale for scattering loss into the atmosphere becomes shorter than the time for transport of plasma to the dayside. This leads to a pronounced day/night asymmetry in the diffuse auroral precipitation and a localized enhancement in conductivity in the post midnight sector. Quantifying the rate of diffuse auroral scattering by each class of wave is therefore imperative for understanding the global distribution of enhanced ionospheric conductivity and its non-linear feedback on plasma transport in the inner magnetosphere. Recent attempts to model the observed global distribution of waves and the associated pattern of electron precipitation will be discussed.