HR: 1340h
AN: SM13B-1317    [Abstracts]
TI: MHD Simulations of the Magnetosphere's Response to Solar Wind Tangential Discontinuities With Dynamic Pressure Changes
AU: * Ober, D M
EM: daniel.ober@hanscom.af.mil
AF: AFRL, VSBXP, 29 Randolf Road, Hanscom AFB, MA 01731,
AU: Burke, W J
EM: william.burke2@hanscom.af.mil
AF: AFRL, VSBXP, 29 Randolf Road, Hanscom AFB, MA 01731,
AU: Burke, W J
EM: william.burke2@hanscom.af.mil
AF: Boston College, 402 St. Clement's Hall, 140 Commonwealth Ave, Chestnut Hill, MA 02467,
AU: Maynard, N C
EM: nelson.maynard@unh.edu
AF: University of New Hampshire, Space Science Center, Durham, NH 03824,
AU: Wilson, G R
EM: gordon.wilson.ctr@hanscom.af.mil
AF: Boston College, 402 St. Clement's Hall, 140 Commonwealth Ave, Chestnut Hill, MA 02467,
AU: Siebert, K D
EM: keith.siebert@sparta.com
AF: Sparta, 39 Simon Street, Nashua, NH 03060,
AB: Global MHD simulations of the coupled solar wind-magnetosphere-ionosphere system are used to examine responses of the magnetosphere to tangential discontinuities (TD) with associated dynamic pressure changes in the solar wind. When a TD carrying an increase in density crosses the earth's bow shock, the transmitted TD convects through the magnetosheath sandwiched between an earthward moving bow shock, and a fast compressional wave. The fast compression wave carries a fraction of the original density change with the remainder at the TD. The arrival of the fast compression wave at the magnetopause initiates enhanced merging, earthward movement of the magnetopause, and a reflected fast wave that propagates upstream through the magnetosheath that brings the bow shock to rest at its new equilibrium position. The bow shock-fast wave interaction generates a second TD that convects through the magnetosheath establishing the final magnetosheath equilibrium state, and returning the merging rate to near its initial value. The transpolar potential increases in response to enhanced merging but then decays slowly towards original values after merging subsides. The reconnection rate in the magnetotail also varies during this process but does not contribute to the strength of the transpolar potential. The magnetosphere's response to a solar wind TD with an associated decrease in density will also be discussed. In this case, the transpolar potential decreases in response to reduced merging and then recovers slowly toward its original value.
DE: 2728 Magnetosheath
DE: 2736 Magnetosphere/ionosphere interactions (2431)
DE: 2752 MHD waves and instabilities (2149, 6050, 7836)
DE: 2753 Numerical modeling
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting