Overview of CISM Magnetosphere Research

1. Overview of CISM Magnetosphere Research Mary Hudson1, Anthony Chan2, Scot Elkington3, Brian Kress1, William Lotko1, Paul Melanson1, David Murr1, John Lyon1, Hans Mueller1, Jeremy Ouellette1,Barrett Rogers1, Simon Shepherd1,Frank Toffoletto2 1 Dartmouth College, 2 Rice University, 3 University of Colorado ?   MI Coupling – Ionospheric Outflow 3D Radiation Belt Electron Modeling________ Introduction/Motivation • Two important extensions of the LFM model with new diagnostic capabilities: • We have developed a multi-fluid version of the LFM code, MF-LFM. • Oxygen outflow, below, appears to have a profound effect on tail reconnection. During single fluid simulations with similar solar wind conditions, the reconnection site is always farther down tail by about 10 RE. The earthward motion of the x-line appears to be related to mass addition in the tail; momentum balance (amount of mass that has to be accelerated) is more favorable if the x-line lies earthward of the single fluid result. See Lyon poster. A 3D full-Lorentz test particle code with first invariant conservation and guiding center switch has been developed using MHD fields calculated with the LFM code, driven by L1 plasma parameters. Pitch angle results, available for the first time with 3D test particle simulations in MHD fields, explain delayed appearance at SAMPEX altitude (2 months) for drift time scale injection events, strongly peaked at 90 deg. The magnetosphere responds as a coupled system to solar wind input provided by MAS-ENLIL or L1 data. The LFM code provides the single fluid MHD description for the magnetospheric system, coupled with the TING/TIEGM ionosphere in the Coupled Magnetosphere-Ionosphere-Thermosphere (CMIT) model. Output from the LFM Model, which has been fully parallelized to provide greater resolution in the inner magnetosphere, is being coupled with the Rice Convection Model to incorporate drift physics. The complete three-way coupled LTR code will be used to specify the time dependent fields which affect SEP and radiation belt particle dynamics. A plasmasphere boundary can be specified by the RCM or inclusion of ionospheric dynamics. Mass outflow, which is important to describing the ionospheric source of magnetospheric plasma, is being approached with development of a multi-fluid version of LFM. Reconnection controls the solar wind coupling, with plans underway to include a Hall-term in the Ohm’s Law solved by the global MHD code. >10 MeV SAMPEX flux post Halloween 2003 Simulated oxygen plume in the magnetosphere, left; closeup of x-line, right. CMIT Study of SEP Access 2. One-fluid LFM simulations using CISM ‘Long Run’(1996) output compare effects of H+ outflow vs. no outflow on transpolar potential pc, hemispherically integrated field-aligned current I||, precipitating electron number flux Fe|| and energy flux Pe||, all at the ionosphere, and the hemispherically averaged Pedersen conductivity p and energy of precipitating electrons e. See below, and Lotko poster. LFM-RCM Coupling: Improved Region 2 Currents and Tail Pressure Initial orbit: 605 -- 31 March 1991 Final Orbit: 756 -- 31 May 1991 =10^3.93 The CMIT model is used to investigate SEP and GCR access to the magnetosphere. The SEP-cutoff model approximates primary SEP fluxes at the Earth using cutoff rigidities. Reverse particle trajectories originating at the Earth's surface are computed in static CMIT field snapshots to locate SEP cutoffs. Cutoff rigidities calculated in a simulation of the 14 May 1997 storm shown, with IGRF field embedded. Time-dependent SEP fluxes are also calculated by isotropically launching a SEP distribution in the solar wind (see Luhmann poster), and following forward Lorentz trajectories (Kress et al. 2005; Hudson et al. 2005), see Kress poster. LFM-RCM Grid Comparison Plots the LFM pressure and field lines for: (a) just before the RCM is called; (b) after 3 hours with only the LFM; (c) the same time as (b) with the effects of the RCM included Significant progress in LFM-RCM coupling this year with density floor in RCM and increased interpolation resolution. a) Shown is comparison of Region 1 & 2 currents with LFM alone and RCM-coupled (top). b) Empirical and model tail pressure (bottom). See Lyon poster.