Identifying Solar Wind Parameters That Affect Plasmapause Location and Radial 
Velocity

B.A. Larsen, D.M. Klumpar, and C.A. Gurgiolo


Plasmapause location is known to be a function of the convection present in the
magnetosphere.  We focus here on determining which solar wind parameters affect
the plasmapause and its radial velocity. Using a plasmapause location database
we have generated from inverted IMAGE/EUV data we have a statistical sample of
plasmapause position and radial velocity for a wide range of solar wind
configurations taken from ACE MAG and SWEPAM data.  IMF Bz in the solar wind is,
of course, a strong contributor. Using principal component analysis we have
determined combinations of solar wind parameters that have a stronger affect on
both plasmapause position and velocity than IMF Bz alone. Creating a new
parameter involving a linear combination of IMF Bz, solar wind proton
temperature, proton velocity, x-component of proton velocity, and RTN longitude
makes for a stronger fit than Bz alone. Using these principal components we have
calculated delay times between the solar wind arrival at the magnetosphere and
the plasmapause location and velocity. The effect is seen first at o hours MLT
and is on the order of 45 minutes for the position. The affect on position then
propagates sunward at the rate of 25 minutes per MLT.

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Global Aspects of Magnetosphere-Ionosphere Coupling, 2006 Yosemite Workshop, 
Yosemite National Park, CA, USA, 7-10 February 2006