HR: 16:45h
AN: SM52E-04    [PDF]
TI: Plasmaspheric Loss Estimates
AU: * Spasojevi\'c, M
EM: mssm@nova.stanford.edu
AF: Space, Telecommunications and Radioscience Laboratory, Stanford University, Stanford, CA 94305-9515 United States
AU: Carpenter, D L
EM: dlc@nova.stanford.edu
AF: Space, Telecommunications and Radioscience Laboratory, Stanford University, Stanford, CA 94305-9515 United States
AU: Sandel, B R
EM: sandel@arizona.edu
AF: Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 87521
AU: Inan, U S
EM: inan@nova.stanford.edu
AF: Space, Telecommunications and Radioscience Laboratory, Stanford University, Stanford, CA 94305-9515 United States
AU: Parks, G K
EM: parks@ssl.berkeley.edu
AF: Space Science Laboratory, University of California, Berkeley, CA 94720
AB: A significant amount of material can be removed from the plasmasphere during periods of enhanced geomagnetic activity. Magnetospheric convection acts to strip away the outer layers of the plasmasphere, and flux tubes in the inner plasmasphere may be significantly depleted as well. Using global images of the ${\rm He^+}$ distribution in the inner magnetosphere, we calculate the amount of ${\rm He^+}$ removed from a volume extending from 1.5 to 5.5 $\rm{R_E}$ during a set of five moderate disturbance periods. For each of the events, approximately 1 to $3 \times 10^{30}$ ${\rm He^+}$ ions were removed, which constituted between 20 and $42\,%$ of the initial ${\rm He^+}$ distribution, in a period of 15 hours or less. The loss percentage is correlated with the number of hours of strongly southward IMF ($B_z < -5$ nT). Between 25 and $40\,%$ of the ${\rm He^+}$ loss appears to occur from within the newly established plasmapause boundary. The total mass removed for each of the events is estimated to be in the range of 50 to 100 metric tons with variations on the order of tens of metric tons depending on the assumed value of the ${\rm He^+}$ to ${\rm H^+}$ density ratio.
DE: 2736 Magnetosphere/ionosphere interactions
DE: 2760 Plasma convection
DE: 2768 Plasmasphere
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting