International Journal of Geomagnetism and Aeronomy
Vol 2, No. 3, January 2001
Effects of geomagnetic storms on the ionosphere and atmosphere
A. D. Danilov and J. Lastovicka
Abstract
A geomagnetic storm is a complex process:
its various
features act at different heights. In the
F2 layer the
midlatitude effect is basically an ionospheric response to
storm-induced changes in the neutral atmosphere, which are
primarily a consequence of a strong Joule heating in the
auroral thermosphere. At lower heights the role of ionization and
photochemical processes increases due to shorter electron lifetimes.
At the base of the
F1 layer (160-170 km) the storm effect is
almost absent. At
E -region maximum a complex action of several
factors results in a slight decrease of
foF2, even though below and
above, the electron density increases. Farther down, in the lower
ionosphere, a strong increase of the electron density is observed
as a consequence of a very strong enhancement of particle
precipitation. In the neutral upper middle atmosphere, the effects
of enhanced precipitation weaken with decreasing altitude and
become insignificant and/or absent in the stratosphere. The effect
of geomagnetic storms reappear in the lower atmosphere but as an
effect of different morphology and origin.