HF radar observations of an isolated substorm after prolonged quiet geomagnetic conditions

M Uspensky*, P Eglitis, N Partamies, G Starkov, A Fabirovsky, H Opgenoorth, T. Pulkkinen, R Pellinen

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Abstract

An isolated substorm on November 17, 1996, which started close to Scandinavia, was preceded by nearly 15 hours quiet geomagnetic condition and was then initiated by a change in the solar-wind parameters. The substorm was observed by the Finland and Iceland CUTLASS radars and the Iceland-West SuperDARN radar. The collected radar areas cover similar to5 hours of the local magnetic evening to midnight sector. The radars were the first instruments to detect a solar wind pressure pulse at 18 UT. They also responded nearly simultaneously to the southward IMF turn, which reached the sub-solar magnetosheath at similar to 1848 UT. Previous to that, the auroral oval was surrounded by echoes (irregularities) from both equatorward and poleward sides, but was nearly empty inside. We suggest that this is a mark of a decreased ionisation inside the auroral oval. A fast equatorward motion of F-layer echoes at 1852-1854 UT indicated the start of the substorm growth-phase development. This occured only 4-6 min later than the IMF turn, similar to 20 min earlier than other ground-based instruments and similar to 40 min before the onset. In the late evening, the initial F-layer core of the growth-phase development was located near a poleward are inside of the quiet-time auroral oval, but earlier in the evening the growth-phase core originated (and traveled into the oval) from the polar cap area. A number of details of the double onset development as they were seen at different irregularity wave-scales nearly simultaneously are also described. UHF EISCAT data collected in the combined CP-1/CP-7 mode (with antenna pointing along B or vertical) support the radar signatures discussed.

Original languageEnglish
Title of host publicationPROCEEDINGS OF THE FIFTH INTERNATIONAL CONFERENCE ON SUBSTORMS
EditorsA Wilson
Pages95-98
Number of pages4
Publication statusPublished - 2000
MoE publication typeA4 Article in a conference publication
EventInternational Conference on Substorms - St. Petersburg, Russian Federation
Duration: 16 May 200020 May 2000
Conference number: 5

Publication series

NameESA SPECIAL PUBLICATIONS
PublisherESA PUBLICATIONS DIVISION C/O ESTEC
Volume443
ISSN (Print)0379-6566

Conference

ConferenceInternational Conference on Substorms
Abbreviated titleICS
CountryRussian Federation
CitySt. Petersburg
Period16/05/200020/05/2000

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