Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.490 IF 1.490
  • IF 5-year value: 1.445 IF 5-year
    1.445
  • CiteScore value: 2.9 CiteScore
    2.9
  • SNIP value: 0.789 SNIP 0.789
  • IPP value: 1.48 IPP 1.48
  • SJR value: 0.74 SJR 0.74
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 88 Scimago H
    index 88
  • h5-index value: 21 h5-index 21
Volume 17, issue 3
Ann. Geophys., 17, 389–404, 1999
https://doi.org/10.1007/s00585-999-0389-6
© European Geosciences Union 1999
Ann. Geophys., 17, 389–404, 1999
https://doi.org/10.1007/s00585-999-0389-6
© European Geosciences Union 1999

  31 Mar 1999

31 Mar 1999

Simultaneous measurements from the Millstone Hill radar and the Active satellite during the SAID/SAR arc event of the March 1990 CEDAR storm

M. Förster1, J. C. Foster2, J. Smilauer3, K. Kudela4, and A. V. Mikhailov5 M. Förster et al.
  • 1GeoForschungsZentrum Potsdam, Germany
  • 2Massachusetts Institute of Technology, Westford, MA, USA
  • 3Institute of Atmospheric Physics, Prague, Czech Republic
  • 4Institute of Experimental Physics, Kosice, Slovak Republic
  • 5IZMIRAN, Russian Academy of Sciences, Troitsk, Russia

Abstract. During a nearby passage of the Active satellite above the Millstone Hill radar on 21 March 1990 at local sunset, the satellite and the radar performed simultaneous measurements of upper ionospheric parameters in nearly the same spatial volume. For this purpose the radar carried out a special azimuth-elevation scan to track the satellite. Direct comparisons of radar data and in situ satellite measurements have been carried out quite rarely. In this case, the coincidence of co-ordinated measurements and active ionospheric-magnetospheric processes during an extended storm recovery phase presents a unique occasion resulting in a very valuable data set. The measurements show generally good agreement both during quiet prestorm and storm conditions and the combination of radar and satellite observations gives a more comprehensive picture of the physical processes involved. We find a close relationship between the rapid westward ion drift peak at subauroral latitudes (SAID event) and the occurrence of a stable auroral red (SAR) arc observed after sunset by an all-sky imager and reported in an earlier study of this event. The SAID electric field is caused by the penetration of energetic ions with energies between about 1 keV and 100 keV into the outer plasmasphere to a latitude equatorward of the extent of the plasmasheet electrons. Charge separation results in the observed polarisation field and the SAID. Unusually high molecular ion densities measured by the satellite at altitudes of 700-870 km at subauroral and auroral latitudes point on strong upward-directed ion acceleration processes and an intense neutral gas upwelling. These structures are collocated with a narrow trough in electron density and an electron temperature peak as observed simultaneously by the radar and the satellite probes.

Key words. Ionosphere (ionosphere-magnetosphere interactions; plasma temperature and density); Magnetospheric physics (plasmasphere).

Publications Copernicus
Download
Citation