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Ann. Geophys., 26, 639-652, 2008
www.ann-geophys.net/26/639/2008/
© European Geosciences Union 2008
Specification of multiple geomagnetic responses to variable solar wind and IMF input
Shing F. Fung1 and Xi Shao2
1Heliospheric Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt MD 20771, USA
2Department of Astronomy, University of Maryland College Park, MD, 20742, USA
Abstract. This paper shows that the state of the
magnetosphere, resulting from continuous but variable forcing of the solar
wind and the interplanetary magnetic field (IMF), can be empirically specified by a
magnetospheric state vector Ψ, consisting of a set of hourly-averaged
magnetospheric driver and response parameters. It is demonstrated that there
exists a correspondence between the magnetospheric driver and multiple
geomagnetic response parameters. This parameter correspondence allows
different magnetopsheric states to be specified by means of a look-up table,
provided that the relative time lags between various driver (e.g.
Vsw, IMF) and response parameters (e.g. Kp, Dst, and AE) are taken
into account. Using the magnetospheric state specifications, multi-scale
geomagnetic responses can then be simultaneously prescribed statistically
from their corresponding driver parameters. Magnetospheric state
specifications have been determined by using magnetospheric state parameter
data taken in 1970–2000. Their validities have been tested by specifying the
multi-geomagnetic responses over three representative intervals: (1) a
magnetic cloud event, (2) a period of multiple storms, and (3) the years of
2001 and 2002. For all the intervals, we have found good correlation (with r>0.75)
between the prescribed and observed geomagnetic indices at hourly
resolution, and the magnetospheric state specifications are thus validated.
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