HR: 09:30h
AN: SM51A-07    [PDF]
TI: Maps of Precipitation by Source Region, Binned by IMF, with Convection Streamlines
AU: * Newell, P T
EM: Patrick.Newell@jhuapl.edu
AF: Johns Hopkins Univ. Appl. Phys. Lab., 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AU: Ruohoniemi, J M
EM: Michael.Ruohoniemi@jhuapl.edu
AF: Johns Hopkins Univ. Appl. Phys. Lab., 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AU: Meng, C -
EM: Ching.Meng@jhuapl.edu
AF: Johns Hopkins Univ. Appl. Phys. Lab., 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AB: Eleven years ago we presented the first map of dayside particle precipitation according to the source of the precipitation (cusp, mantle, polar rain, etc). Here we present a modernization of the effort with several enhancements. The maps are created in a fully automated fashion, with, for example, the cusp centered at its centroid latitude for each half hour bin of MLT, with a width equal to the statistical difference between the poleward and equatorward edges. The data is binned according to the sign of the IMF clock-angle in the By-Bz plane. SuperDARN convection patterns compiled under the identical conditions are overlayed. The results include at least one "surpise" that likely should have been predicted years ago. Specifically the mantle is asymmetric about noon. The pre-noon mantle is appreciably thicker than the postnoon mantle, especially for By$>0$. This asymmetry matches well an asymmetry in convection flows, in which most of the conversion of closed field lines to open occurs prenoon - and where the flow patterns are also more perpendicular to the open-closed boundary. Only a minority of the open-closed field line conversion on the dayside occurs near the cusp. The matching of the convection patterns with the particle data shows clearly that field lines are converted from closed regions to open away from noon. Merging is thus active throughout the frontside magnetosphere, and not just near the subsolar region. Field lines which merge well away from noon do not experience enough particle inflow against the solar wind direction to produce anything more than a weak, de-energerized (mantle) precipitation in the ionosphere.
DE: 2463 Plasma convection
DE: 2720 Energetic particles, trapped
DE: 2724 Magnetopause, cusp, and boundary layers
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting