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Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 32, 1293-1302, 2014
https://doi.org/10.5194/angeo-32-1293-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Regular paper
22 Oct 2014
Analysis of double-step response to an interplanetary shock in the dayside magnetosphere
K. Andréeová1, L. Juusola2, E. K. J. Kilpua1, and H. E. J. Koskinen1,2 1Department of Physics, P.O. Box 64, University of Helsinki, Helsinki, Finland
2Finnish Meteorological Institute, P.O. Box 503, Helsinki, Finland
Abstract. We present an analysis of double-step magnetic field enhancement caused by interplanetary (IP) shock impacts on the Earth's magnetosphere. The structures were observed by the GOES-8, 10, 11, and 12 spacecraft in the dayside geostationary orbit, particularly during northward interplanetary magnetic field (IMF) conditions. The double-step structures, similar to what is observed in the ground horizontal magnetic field (H) component at low and mid latitudes, were observed preferentially on the dayside. Structures observed around 12–15 magnetic local time (MLT) displayed the steepest initial enhancement step, followed by a magnetic field strength decrease before the second enhancement step. At other dayside MLTs of the geostationary orbit, the initial response was smoother, and no decrease was observed before the second step. We suggest that this MLT asymmetry in the decrease of the total magnetic field is caused by the pushing of the plasmaspheric ions over the geostationary orbit due to the magnetospheric compression.

Citation: Andréeová, K., Juusola, L., Kilpua, E. K. J., and Koskinen, H. E. J.: Analysis of double-step response to an interplanetary shock in the dayside magnetosphere, Ann. Geophys., 32, 1293-1302, https://doi.org/10.5194/angeo-32-1293-2014, 2014.
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