CLUSTER measurements of space plasmas in the context of global modeling and 
observations: the telescope-microscope connection

D.N. Baker (1), S.R. Elkington (1), M.J. Wiltberger (2)

(1) Laboratory for Atmospheric and Space Physics, University of Colorado, 1234
Innovation Drive, Boulder, CO 80303-7814
(2) NCAR/HAO, 3450 Mitchell Lane, Boulder, CO


The magnetospheric research community has long sought the capability to view the
Sun-Earth system in a global way and concurrently to probe the microphysical
details of key physical regions. This objective has now been substantially
realized with the combination of the CLUSTER constellation and global imaging
missions. With the addition of SOHO, ACE, FAST, SAMPEX, POLAR, and various
geostationary orbit spacecraft, there is an ability to apply both telescopic and
microscopic principles. Many recent examples serve to illustrate the observational
power of these new tools. Using events from 2001 and 2003, we have observed strong
geomagnetic storms and have studied powerful compression of the magnetosphere and
concomitant particle injection events. Using tail crossing events in 2001-2002,
CLUSTER observed clear substorm sequences of events in the mid-magnetotail region
(X "< 19RE). In these cases, CLUSTER data reveal microphysical details while other
spacecraft show the global, macroscopic context. We have used the
Lyon-Fedder-Mobarry MHD simulation code to numerically model several of these
specific events. The new observations and model comparisons are leading to new
understandings of magnetospheric processes. Several of the cases to be presented
show global features consistent with present-day models of substorm and storm
dynamics, but the specific details reveal heretofore unappreciated aspects of
processes such as magnetic reconnection and particle acceleration.

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Presented at the 35th COSPAR Scientific Assembly, Paris, France, July 18-25, 2004.