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Cluster and DMSP observations of SAID electric fields
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2007 (English)In: Journal of Geophysical Research, ISSN 0148-0227, Vol. 112, no A5, A05219- p.Article in journal (Refereed) Published
Abstract [en]

[1] We report on magnetically conjugate Cluster and the Defense Meteorological Satellite Program (DMSP) satellite observations of subauroral ion drifts (SAID) during moderate geomagnetic activity levels on 8 April 2004. To our knowledge, the field-aligned separation of DMSP and Cluster (approximate to 28,000 km) is the largest separation ever analyzed with respect to the SAID phenomenon. Nonetheless, we show coherent, subauroral magnetosphere-ionosphere (MI) coupling along an entire field line in the post-dusk sector. The four Cluster satellites crossed SAID electric field channels with meridional magnitude E-M of 25 mV/m in situ and latitudinal extent Delta Lambda approximate to 0.5 degrees in the southern and northern hemispheres near 07:00 and 07:30 UT, respectively. Cluster was near perigee (R approximate to 4 R-E) and within 5 degrees (15 degrees) of the magnetic equator for the southern ( northern) crossing. The SAID were located near the plasmapause-within the ring current-plasmasphere overlap region. Downward field-aligned current signatures were observed across both SAID crossings. The most magnetically and temporally conjugate SAID field from DMSP F16A at 07:12 UT was practically identical in latitudinal size to that mapped from Cluster. Since the DMSP ion drift meter saturated at 3000 m/s (or similar to 114 mV/m) and the electrostatically mapped value for E-M from Cluster exceeded 300 mV/m, a magnitude comparison of E-M was not possible. Although the conjugate measurements show similar large-scale SAID features, the differences in substructure highlight the physical and chemical diversity of the conjugate regions.

Place, publisher, year, edition, pages
2007. Vol. 112, no A5, A05219- p.
National Category
Physical Sciences
URN: urn:nbn:se:uu:diva-150850DOI: 10.1029/2006JA012065ISI: 000246850100007OAI: oai:DiVA.org:uu-150850DiVA: diva2:409070
Available from: 2011-04-07 Created: 2011-04-06 Last updated: 2011-04-07Bibliographically approved

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Swedish Institute of Space Physics, Uppsala Division
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