The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF
We document the detailed dynamics of the dayside aurora in the \sim1200-1600 MLT sector in response to a sharp southward turning of the interplanetary magnetic field (IMF) under negative IMF By conditions. Features not documented in previous work are elucidated by using two meridan scanning photomet...
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ftuninhampshire:oai:scholars.unh.edu:cmerg-1292 2023-05-15T17:48:28+02:00 The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF Sandholt, P. E. Farrugia, Charlie J. Lybekk, B. 1999-09-30T07:00:00Z application/pdf https://scholars.unh.edu/cmerg/293 https://scholars.unh.edu/cgi/viewcontent.cgi?article=1292&context=cmerg unknown University of New Hampshire Scholars' Repository https://scholars.unh.edu/cmerg/293 https://scholars.unh.edu/cgi/viewcontent.cgi?article=1292&context=cmerg http://creativecommons.org/licenses/by/3.0/ CC-BY Coronal Mass Ejection Research Group Mangetospheric physics (magnetopause · cusp and boundary layers solar wind-magnetosphere interactions auroral phenomena) text 1999 ftuninhampshire 2023-01-30T22:05:23Z We document the detailed dynamics of the dayside aurora in the \sim1200-1600 MLT sector in response to a sharp southward turning of the interplanetary magnetic field (IMF) under negative IMF By conditions. Features not documented in previous work are elucidated by using two meridan scanning photometers (separated by 2 h) and an all-sky auroral imager in Ny Ålesund, Svalbard (75.5°MLAT) in combination with magnetograms from stations on Svalbard, covering the latitude range 71°75°MLAT. The initial auroral response may be divided into three phases consisting of: (1) intensification of both the red (630.0 nm) and green (557.7 nm) line emissions in the cusp aurora near 1200 MLT and ~100 km equatorward shift of its equatorward boundary, at ~75°MLAT, (2) eastward and poleward expansions of the cusp aurora, reaching the 1430 MLT meridian after 5-6 min, and (3) east-west expansion of the higher-latitude aurora (at ~77°78°MLAT) in the postnoon sector. The associated magnetic disturbance is characterized by an initial positive deflection of the X-component at stations located 100-400 km south of the aurora, corresponding to enhanced Sunward return flow associated with the merging convection cell in the post-noon sector. The sequence of partly overlapping poleward moving auroral forms (PMAFs) during the first 15 min, accompanied by corresponding pulsations in the convection current, was followed by a strong westward contraction of the cusp aurora when the ground magnetograms indicated a temporary return to the pre-onset level. These observations are discussed in relation to the Cowley-Lockwood model of ionospheric response to pulsed magnetopause reconnection. Text Ny Ålesund Ny-Ålesund Svalbard University of New Hampshire: Scholars Repository Svalbard Ny-Ålesund Lockwood ENVELOPE(167.400,167.400,-84.150,-84.150) Cowley ENVELOPE(-134.909,-134.909,60.518,60.518) |
institution |
Open Polar |
collection |
University of New Hampshire: Scholars Repository |
op_collection_id |
ftuninhampshire |
language |
unknown |
topic |
Mangetospheric physics (magnetopause · cusp and boundary layers solar wind-magnetosphere interactions auroral phenomena) |
spellingShingle |
Mangetospheric physics (magnetopause · cusp and boundary layers solar wind-magnetosphere interactions auroral phenomena) Sandholt, P. E. Farrugia, Charlie J. Lybekk, B. The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF |
topic_facet |
Mangetospheric physics (magnetopause · cusp and boundary layers solar wind-magnetosphere interactions auroral phenomena) |
description |
We document the detailed dynamics of the dayside aurora in the \sim1200-1600 MLT sector in response to a sharp southward turning of the interplanetary magnetic field (IMF) under negative IMF By conditions. Features not documented in previous work are elucidated by using two meridan scanning photometers (separated by 2 h) and an all-sky auroral imager in Ny Ålesund, Svalbard (75.5°MLAT) in combination with magnetograms from stations on Svalbard, covering the latitude range 71°75°MLAT. The initial auroral response may be divided into three phases consisting of: (1) intensification of both the red (630.0 nm) and green (557.7 nm) line emissions in the cusp aurora near 1200 MLT and ~100 km equatorward shift of its equatorward boundary, at ~75°MLAT, (2) eastward and poleward expansions of the cusp aurora, reaching the 1430 MLT meridian after 5-6 min, and (3) east-west expansion of the higher-latitude aurora (at ~77°78°MLAT) in the postnoon sector. The associated magnetic disturbance is characterized by an initial positive deflection of the X-component at stations located 100-400 km south of the aurora, corresponding to enhanced Sunward return flow associated with the merging convection cell in the post-noon sector. The sequence of partly overlapping poleward moving auroral forms (PMAFs) during the first 15 min, accompanied by corresponding pulsations in the convection current, was followed by a strong westward contraction of the cusp aurora when the ground magnetograms indicated a temporary return to the pre-onset level. These observations are discussed in relation to the Cowley-Lockwood model of ionospheric response to pulsed magnetopause reconnection. |
format |
Text |
author |
Sandholt, P. E. Farrugia, Charlie J. Lybekk, B. |
author_facet |
Sandholt, P. E. Farrugia, Charlie J. Lybekk, B. |
author_sort |
Sandholt, P. E. |
title |
The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF |
title_short |
The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF |
title_full |
The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF |
title_fullStr |
The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF |
title_full_unstemmed |
The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF |
title_sort |
dynamic cusp aurora on 30 november 1997: response to southward turning of the imf |
publisher |
University of New Hampshire Scholars' Repository |
publishDate |
1999 |
url |
https://scholars.unh.edu/cmerg/293 https://scholars.unh.edu/cgi/viewcontent.cgi?article=1292&context=cmerg |
long_lat |
ENVELOPE(167.400,167.400,-84.150,-84.150) ENVELOPE(-134.909,-134.909,60.518,60.518) |
geographic |
Svalbard Ny-Ålesund Lockwood Cowley |
geographic_facet |
Svalbard Ny-Ålesund Lockwood Cowley |
genre |
Ny Ålesund Ny-Ålesund Svalbard |
genre_facet |
Ny Ålesund Ny-Ålesund Svalbard |
op_source |
Coronal Mass Ejection Research Group |
op_relation |
https://scholars.unh.edu/cmerg/293 https://scholars.unh.edu/cgi/viewcontent.cgi?article=1292&context=cmerg |
op_rights |
http://creativecommons.org/licenses/by/3.0/ |
op_rightsnorm |
CC-BY |
_version_ |
1766154552105500672 |