Dartmouth Events

Physics & Astronomy Space Plasma Seminar - Prof Mary Hudson, Dartmouth College

Title: "Modeling the Radiation Belt Electron Response to CME-Driven Storms: The First Three Years of the Van Allen Probes"

Tuesday, September 22, 2015
4:00pm – 5:00pm
Wilder 111
Intended Audience(s): Public
Categories: Lectures & Seminars

Abstract: Recent geomagnetic storms at solar maximum have produced dynamic variations in outer zone radiation belt electron flux measured in detail by the Van Allen Probes twin spacecraft, launched August 30, 2013. Both enhanced flux and sudden dropouts have been observed, which characterize Coronal Mass Ejection (CME)-driven storms dominating variability around solar maximum. High time resolution measurements of waves which modulate that variability are also made by the Van Allen Probes. In addition to strong evidence of prompt magnetopause loss provided by the Van Allen Probes, observations of prompt radial transport as well as local acceleration have been reported. Results will be shown from modeling flux enhancements due to plasmasheet electron injection during four ‘equinoctal storms’ in October 2012 and 2013; and March 2013 and 2015. The latter was the largest geomagnetic storm of the past decade. The technique described follows electron test particles in global MHD fields using the Lyon-Fedder-Mobarry MHD code driven by upstream solar wind measurements coupled to the Rice Convection Model of the ring current. Test particle electrons are followed in 3D and weighted to provide fluxes which can be compared directly with in situ measurements. Plasmasheet electrons can be transported inside geosynchronous orbit, acquiring energies ~ 1 MeV, after loss to the magnetopause and to the atmosphere depletes the outer zone immediately following the arrival of CME shocks. The cycle of flux dropout and enhancement during storm intervals has also been compared with radial diffusion over relatively quiet periods, which are well-modeled by a diffusion code.

For more information, contact:
Tressena Manning
603-646-2854

Events are free and open to the public unless otherwise noted.