Contact Disclaimer
Annales Geophysicae
Copernicus.org Home EGU Copernicus Publications Copernicus Meetings
  Home  
  General Information  
  Submission  
  Special Issues  
  Evaluation  
  Production  
  Subscription  
  Online Library  
  Recent Papers  
  Volumes and Issues  
  Special Issues  
  Topical Library  
  Library Search  
  Title and Author Search  
  Volumes and Issues      Contents of Issue 9      Special Issue     
Ann. Geophys., 20, 1377-1384, 2002
www.ann-geophys.net/20/1377/2002/
© European Geosciences Union 2002


Positive storm effects in the dayside polar ionospheric F-region observed by EISCAT and ESR during the magnetic storm of 15 May 1997

S. Y. Ma1, H. T. Cai1, H. X. Liu2, K. Schlegel3, and G. Lu2
1Dept. of Space Physics, College of Electronic Information, Wuhan University, Wuhan 430072, P. R. China
2High Altitude Observatory, National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80301, USA
3Max-Planck-Institut für Aeronomie, D-37191 Katlenburg-Lindau, Germany
Correspondence to: S. Y. Ma (syma@whu.edu.cn)

Abstract. EISCAT/ESR radar data and in situ FAST and POLAR satellite observations are coordinately analyzed to investigate positive ionospheric storm effects in the dayside upper F-region in both the polar cap and the auroral oval during the magnetic storm of 15 May 1997. An ionization enhancement, lasting for about 2.5 h, appeared first over the EISCAT site around magnetic noon; about one hour later, a similar ionization enhancement was also seen over ESR. During the concerned time period ion energy spectra measured on board FAST show clearly continuous energy-latitude dispersion when the satellite passed by over the EISCAT latitude. This implies that EISCAT was located under the polar cusp region which was highly active, and expanded greatly equatorwards due to magnetopause reconnections during long-lasting southward IMF. Simultaneously, soft particles of the magnetosheath precipitated into the F-region ionosphere and caused the positive storm effects over EISCAT. The coincident increase in electron temperature at EISCAT gives additional evidence for soft particle precipitation. Consistently, POLAR UV images show strong dayside aurora extending to as low as 62° N magnetic latitude. The ionization enhancement over ESR, however, seems not to be caused by local particle precipitation, evidenced by a lack of enhanced electron temperature. The observed plasma convection velocity and data-fitted convection patterns by AMIE suggested that it is likely to be a polar patch originating from the cusp region and traveling to the ESR site.

Key words. Ionosphere (auroral ionosphere; particle percipitation) Magnetospheric physics (storms and substorms)


Full Article in PDF (528 KB)
  Library Search ANGEO  
       
  Special Services  
  Printer-friendly Version  
  Bookmark  
  Download Acrobat Reader  
  News  
  ISI Impact Factor: 1.427 (2007)
 
Annales Geophysicae is launching a new section: AnGeo Communicates
 
© Copernicus 2004–2006