Abstract
Neutral thermospheric wind patterns at high latitudes obtained
from cross-track acceleration measurements of the CHAMP satellite
above both polar regions are used to deduce statistical neutral
wind vorticity distributions and were analyzed in their dependence on
the Interplanetary Magnetic Field (IMF).
The average pattern confirms the large duskside anticyclonic vortex seen
in the average wind pattern and reveals a positive (cyclonic) vorticity on the
dawnside, which is almost equal in magnitude to the duskside negative one.
The IMF dependence of the vorticity pattern resembles the characteristic
field-aligned current (FAC) and ionospheric plasma drift pattern known
from various statistical studies obtained under the same sorting conditions
as, e.g., the EDI Cluster statistical drift pattern.
There is evidence for hemispheric differences in the average magnitudes
of the statistical patterns both for plasma drift and even more for the
neutral wind vorticity.
The paper aims at a better understanding of the globally interconnected complex
plasma physical and electrodynamic processes of Earth's upper atmosphere by means
of first-principle numerical modeling using the Upper Atmosphere Model (UAM).
The simulations of, e.g., thermospheric neutral wind and mass density at high
latitudes are compared with CHAMP observations for varying IMF conditions.
They show an immediate response of the upper atmosphere and its high
sensitivity to IMF changes in strength and orientation.
Citation
ID:
245861
Ref Key:
frster2012advancesnumerical