[IGPP Everyone] TODAY: Space Physics Seminar, 10/9, 3:30pm: Impact of the azimuthal component of the IMF on Magnetosphere-Ionosphere coupling (P. Tenfjord, Univ. Bergen, Norway)

[Emmanuel V. Masongsong]

SPACE PHYSICS SEMINAR 

DEPARTMENT OF EARTH, PLANETARY, AND SPACE SCIENCES 

DEPARTMENT OF ATMOSPHERIC AND OCEANIC SCIENCES 

UNIVERSITY OF CALIFORNIA, LOS ANGELES 

(EPSS M288A, AOS M275A ) 







Paul Tenfjord 


University of Bergen, Birkeland Centre for Space Science, Norway 



Impact of the azimuthal component (By) of the Interplanetary Magnetic Field (IMF) on Magnetosphere-Ionosphere coupling 




The solar wind’s IMF By component is believed to be the cause of a number of asymmetric features in both the magnetosphere and ionosphere. We investigate it's role in the generation of Birkeland currents, comparing observations from AMPERE and MHD simulations. When the IMF reconnects with the terrestrial magnetic field with a non-vanishing By flux transport is asymmetrically distributed between the two hemispheres. The magnetosphere then imposes asymmetric forces on the ionosphere, and the effects on ionospheric flow is characterized by distorted convection cell patterns, often referred to as "banana" and "orange" cell patterns. The flux asymmetrically added to the lobes results in a non-uniform induced By in the closed magnetosphere. By including the dynamics of the system we introduce a mechanism that predicts asymmetric Birkeland currents at conjugate footpoints. We argue that the induced By produces asymmetrical Birkeland currents as a consequence of asymmetric stress balance between the hemispheres. Associated with these currents we expect fast localized ionospheric azimuthal flows present in one hemisphere, but not necessarily in the other. 




In part two I present an ongoing study where we estimate the timescales of the above processes. The estimates of the timescales on which this process occurs are highly divergent in the literature. We perform a multi-spacecraft and MHD analysis to study the response in different regions of the magnetosphere (on closed field lines) for a single event with out of plane IMF Bz < 0 and varying By conditions. We also show a a superposed analysis of IMF By reversals looking at the GOES dataset. The high-latitude ionospheric response is also analysed using AMPERE. We show that the response time and reconfiguration time occurs on timescales in the order of tens of minutes. 




Friday, October 9, 2015 

Room 6704 Geology 

3:30 - 5:00 PM 



Refreshments served after the seminar in Room 6850. 



In-Charge 
M. Velli 


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