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Ann. Geophys., 14, 1356-1361, 1996
www.ann-geophys.net/14/1356/1996/
© European Geosciences Union 1996
Models of field-aligned currents needful to simulate the substorm variations of the electric field and other parameters observed by EISCAT
M. A. Volkov1 and A. A. Namgaladze1,2
1Polar Geophysical Institute, 15 Halturina St., Murmansk, 183010, Russia
2Murmansk State Technical University, 2 Sportivnaya St., Murmansk, 183010, Russia
Abstract. We have used the global numerical model of
the coupled ionosphere-thermosphere-protonosphere system to simulate the
electric-field, ion- and electron-temperature and -concentration variations
observed by EISCAT during the substorm event of 25 March 1987. In our previous
studies we adopted the model input data for field-aligned currents and
precipitating electron fluxes to obtain an agreement between observed and
modelled ionospheric variations. Now, we have calculated the field-aligned
currents needful to simulate the substrom variations of the electric field and
other parameters observed by EISCAT. The calculations of the field-aligned
currents have been performed by means of numerical integration of the
time-dependent continuity equation for the cold magnetospheric electrons. This
equation was added to the system of the modelling equations including the
equation for the electric-field potential to be solved jointly. In this case the
inputs of the model are the spatial and time variations of the electric-field
potential at the polar-cap boundaries and those of the cold magnetospheric
electron concentration which have been adopted to obtain the agreement between
the observed and modelled ionospheric variations for the substorm event of 25
March 1987. By this means it has been found that during the active phase of the
substorm the current wedge is formed. It is connected with the region of the
decreased cold magnetospheric electron content travelling westwards with a
velocity of about 1 km s–1 at ionospheric levels.
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