Magnetosphere Seminars

October 30, 2012 – “Fast Flow Channels and Ionospheric Joule Heating in the Cusp Region Under Non-Southward IMF”

Speaker:Rick Wilder (LASP)
Date:Tuesday, Oct 30, 2012
Time:4:00 PM
Location:LASP Space Science Building, room N248 upstairs. Map

Seminar Abstract:

We investigate fast plasma flows in the high-latitude cusp region during periods of extreme northward, dawnward, and duskward interplanetary magnetic field (IMF). During such periods, magnetic reconnection occurs near the cusp, leading to extreme energy deposition into the dayside ionosphere-thermosphere system. We use precipitating particle data from the DMSP spacecraft, as well as assimilation of ground magnetometers, SuperDARN radar measurements, and DMSP driftmeter observations to investigate three cases. We examine the magnetic field topology in relation to the high-latitude ionospheric convection pattern to examine the impact of magnetospheric structure on seasonal asymmetries in dayside convection, as well as the magnetospheric source of extreme dayside ionosphere-thermosphere energy deposition. We find that an inter-hemispheric reconnection cycle can explain a large portion of seasonal convection asymmetries under northward IMF. We also find that during dawnward and duskward IMF, extreme energy deposition into the ionosphere-thermosphere lies on fast flow channels that are likely caused by magnetic reconnection on the high latitude flanks near the cusp. Comparisons between observations and the BATS-R-US MHD simulation suggest that the fastest portion of the flow channels maps to reconnection exhaust jets that flow inside the magnetopause.