Physics
Scientific paper
Dec 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufmsa14a..07a&link_type=abstract
American Geophysical Union, Fall Meeting 2009, abstract #SA14A-07
Physics
[2407] Ionosphere / Auroral Ionosphere, [2409] Ionosphere / Current Systems, [2431] Ionosphere / Ionosphere/Magnetosphere Interactions
Scientific paper
Analysis of plasma drifts relative to field aligned currents reveal a persistent enhancement of sunward flows at dusk relative to those at dawn. We use Iridium and DMSP magnetometer data to determine the global distribution of Birkeland currents and place the DMSP drift meter observations in the context of the currents. In general, the Birkeland currents at dawn and dusk are comparable, whereas the flows are not. At dawn, the flows display a single maximum located between the Region 1 and Region 2 currents whereas at dusk the flow has two peaks, one between the Region 1 and Region 2 currents and a second local maximum within the Region 2 currents but equatorward of the maximum current. This secondary dusk enhancement corresponds to the sub-auroral polarization stream (SAPS) but is present for strong and moderate convection suggesting that it is a persistent feature of the coupled magnetosphere-ionosphere system. It has been suggested that the equatorward dusk flow enhancement may be the magnetospheric response to the conductance distribution that minimizes energy ionospheric energy dissipation. In this view, the key difference between dusk and dawn is the sense of the Region 2 currents, downward at dusk and upward at dawn. Because upward currents are highly correlated with discrete electron aurora and enhanced ionospheric conductance, the Region 2 latitude conductance is consistently higher at dawn than at dusk, and the energy dissipated per unit flow is higher at dawn that at dusk. The convection return flows then preferentially occur at dusk. We present MHD simulations in which the return flow distribution is assessed for various ad-hoc ionospheric conductance distributions. Three different ionospheric conductance distributions are used: uniform, higher at dusk than at dawn and higher at dawn than at dusk. Differences in the dawn-dusk distribution of convection flows are then used to determine whether the magnetospheric flow distribution is redistributed in response to the ionospheric conductance distribution. Simulations both with and without the ring current simulation module (Rice Convection Model) are used to assess whether the distribution in flows depend on the presence of ion drift physics.
Anderson Benjamin J.
Dyrud Lars
Korth Haje
No associations
LandOfFree
ENHANCED DUSK-SIDE IONOSPHERIC CONVECTION: MAGNETOSPHERIC RESPONSE TO IONOSPHERIC CONDUCTIVITY DISTRIBUTION does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with ENHANCED DUSK-SIDE IONOSPHERIC CONVECTION: MAGNETOSPHERIC RESPONSE TO IONOSPHERIC CONDUCTIVITY DISTRIBUTION, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and ENHANCED DUSK-SIDE IONOSPHERIC CONVECTION: MAGNETOSPHERIC RESPONSE TO IONOSPHERIC CONDUCTIVITY DISTRIBUTION will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1778035