Geoscience Reference
In-Depth Information
Fig. 4.2
Average North Hemisphere thermospheric wind pattern given in polar geomagnetic
coordinates (>60
ı
magnetic latitude) at F-layer heights (
400 km) using cross-track CHAMP
accelerometer data of the full year 2003 as obtained from a recent European Space Agency (ESA)
study (Doornbos et al.
2010
). The sun's position of the dial is at top of the figure, with dawn side
at
right
and dusk to the
left
. The wind direction is shown by small vectors with the origin in the
dots at the bin's position; their length and color coding indicates the wind vector magnitude with
the scale given on
top
As already shown by earlier theoretical work and numerical modeling (e.g.,
Killeen and Roble
1984
; Killeen et al.
1995
; Rees et al.
1986
; Thayer and Killeen
1993
), the dusk side vorticity as driven by the plasma component is preferably
sustained by a favorable action of the Coriolis force. Any detailed analysis of
high-latitude dynamics and energetics requires numerical methods and modelings
because of the complexity of these processes (thermodynamic, electrodynamic, gas
kinetic, etc.).
To obtain information about the external driving forces from IMF and solar
wind interactions with the magnetosphere, we consider patterns of magnetospheric
convection drift velocities, which map into the upper ionosphere at high latitudes,
provided the characteristic time scales are large enough to be considered as quasi-
static. There are numerous measurement methods, both ground based (e.g., radars
