Journal cover Journal topic
Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 26, 517-531, 2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.
26 Mar 2008
Optical, radar, and magnetic observations of magnetosheath plasma capture during a positive IMF Bz impulse
V. Safargaleev1, A. Kozlovsky2,3, T. Sergienko4, T. K. Yeoman5, M. Uspensky6, D. M. Wright5, H. Nilsson4, T. Turunen3, and A. Kotikov7 1Polar Geophysical Institute, Apatity, 184200, Russia
2Department of Physical Science, University of Oulu, Oulu, 90014, Finland
3Sodankylä Geophysical Observatory, Sodankylä, 99600, Finland
4Swedish Institute of Space Physics, 981 28, Kiruna, Sweden
5Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK
6Finnish Meteorological Institute, 00101 Helsinki, Finland
7Institute of Physics, St.Petersburg State University, St. Petersburg, 198504, Russia
Abstract. We present a multi-instrument study of the ionospheric response to a northward turning of the IMF. The observations were made in the near-noon (11:00 MLT) sector on Svalbard (at 75° MLAT). The data set includes auroral observations, ionospheric flows obtained from the EISCAT and CUTLASS radars, the spectral width of the HF radar backscatter, particle precipitation and plasma flow data from the DMSP F13 satellite, and Pc1 frequency band pulsations observed by induction magnetometers. Careful collocation of all the observations has been made with the HF radar backscatter located by a ray-tracing procedure utilizing the elevation angle of arrival of the signals and an ionospheric plasma density profile. Prior to IMF turning northward, three auroral arcs were observed at the poleward boundary of the closed llbl, inside the llbl, and in the equatorward part of the llbl, respectively. The northward IMF turning was accompanied by enhanced HF radar returns with a broad Doppler spectrum collocated with the arcs. The auroral arcs shifted poleward whereas the backscatter region moved in the opposite direction, which is consistent, respectively, with reconnection beyond the cusp and the capturing of magnetosheath plasma during northward IMF. Locally, magnetic noise enhancement in the Pc1 frequency band occurred simultaneously with the anomalous radar backscatter, and the absence of such signals at more remote magnetic observatories indicates a local generation of the Pc1 turbulence, which is collocated with the radar backscatter. Finally, we discuss possible interpretation errors which may be caused by limited observational data.

Citation: Safargaleev, V., Kozlovsky, A., Sergienko, T., Yeoman, T. K., Uspensky, M., Wright, D. M., Nilsson, H., Turunen, T., and Kotikov, A.: Optical, radar, and magnetic observations of magnetosheath plasma capture during a positive IMF Bz impulse, Ann. Geophys., 26, 517-531,, 2008.
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