The Effect of Strong (Dst < -100) Disturbances on Plasmasphere Composition

Abstract:

The aim of the ISES program (Integrating the Earth-Sun System) at NRL is to model the coupled solar wind-magnetosphere-plasmasphere-ionosphere-thermosphere system. In this investigation, the NRL SAMI3 ionosphere/plasmasphere code[1], coupled to the solar wind via the Weimer05 magnetospheric potential, is used to simulate H+ and He+ populations in the plasmasphere during strongly-disturbed (Dst < -100), moderate (-100 < Dst < -9) and quiet (-9 < Dst <-3) geomagnetic conditions. The SAMI3 ionosphere code includes 7 ion species (H+, He+, O+, N+, O2+, N2+, NO+), each treated as a separate fluid, with temperature equations being solved for H+, He+, O+ and e-. Model results from two different time periods in 2001 are compared to statistical results for number density and mass density versus L shell, based on measurements during 1999-2001[2]. Preliminary results suggest that the heavy ion torus, a configuration where the average ion mass increases with L, may be largely a dayside phenomenon. We will discuss ISES, the SAMI3 results, and the comparison to data.

[1] Huba, J. and J. Krall, 2013, ``Modeling the plasmasphere with SAMI3,'' Geophys. Res. Lett. 40, 6--10, doi:10.1029/2012GL054300

[2] Berube, D., M. B. Moldwin, S. F. Fung and J. L. Green, 2005, ``A plasmaspheric mass density model and its constraints on heavy ion concentration,'' J. Geophys. Res., 110, A04212, doi:10.1029/2004JA010684

Research supported by NRL base funds and NASA.