IMAGE EUV Observations of Plasmaspheric Drainage Plumes

M.L. Adrian and D.L. Gallagher


Plasmaspheric drainage plumes appear in the aftermath of periods of enhanced
convection/erosion and are interpreted as a near-equatorial signature of the
redistribution of thermal plasma along streamlines.  Analysis of IMAGE/EUV
observations from ÒFirst LightÓ through the end of calendar year 2002 reveals
that for Kp ³ 3, there is an 84% probability of observing a plasmaspheric plume
in EUV data.  We present a statistical analysis of the geomagnetic conditions
[Kp, Dst, and solar wind-induced electric field] associated with EUV plume
observations.  This analysis yields a peak in observational probability when Kp
= 4 and Dst = Ð50 nT.  Additionally, EUV plume observations are associated with
a solar wind-induced convection electric field at Earth [EY,SM] characterized by
bi-modal behavior with a positive node peaked at ~4 mV mÐ1 and a negative node
that peaks at Ð2 mV mÐ1.  Analysis of the time rate of change of the
plume-associated EY,SM indicates that once the mechanism for plume formation is
initiated, a slowly changing convection environment is required to allow for
sufficient plume development prior to EUV detection.

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