UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Examining Local Time Variations in the Gains and Losses of Open Magnetic Flux During Substorms

Mooney, MK; Forsyth, C; Rae, IJ; Chisham, G; Coxon, JC; Marsh, MS; Jackson, DR; ... Hubert, B; + view all (2020) Examining Local Time Variations in the Gains and Losses of Open Magnetic Flux During Substorms. Journal of Geophysical Research: Space Physics , 125 (4) , Article e2019JA027369. 10.1029/2019ja027369. Green open access

[thumbnail of Forsyth_Examining Local Time Variations in the Gains and Losses of Open Magnetic Flux During Substorms_VoR.pdf]
Preview
Text
Forsyth_Examining Local Time Variations in the Gains and Losses of Open Magnetic Flux During Substorms_VoR.pdf - Published Version

Download (19MB) | Preview

Abstract

The open magnetic flux content of the magnetosphere varies during substorms as a result of dayside and nightside reconnection. The open flux can be calculated from the area of the polar cap, delineated by the open‐closed field line boundary (OCB). This study presents a superposed epoch analysis of the location of the OCB and the change in the magnetic flux content in individual nightside MLT sectors during substorm growth, expansion and recovery phases. Far ultraviolet (FUV) observations from the IMAGE satellite are used to derive a proxy of the OCB location. In the hour prior to substorm onset, the total nightside flux content increases by up to 0.12 GWb on average, resulting in an equatorward expansion of the OCB. Following substorm onset, the OCB contracts towards the pole as the open magnetic flux content decreases by up to 0.14 GWb on average but the rate of decrease of the total nightside open flux content differs by 5‐66% between the three IMAGE FUV instruments. The OCB does not contract poleward uniformly in all nightside MLT sectors after substorm onset. Close to the substorm onset MLT sector, the OCB contracts immediately following substorm onset however the OCB in more dawnward and duskward MLT sectors continues to expand equatorward for up to 120 minutes after substorm onset. Despite the continued increase in flux in these sectors after substorm onset, the total nightside flux content decreases immediately at substorm onset, indicating that the nightside reconnection rate exceeds the dayside rate following substorm onset.

Type: Article
Title: Examining Local Time Variations in the Gains and Losses of Open Magnetic Flux During Substorms
Open access status: An open access version is available from UCL Discovery
DOI: 10.1029/2019ja027369
Publisher version: https://doi.org/10.1029/2019ja027369
Language: English
Additional information: © 2020 The Authors. This is an open access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/).
Keywords: open‐closed field line boundary, substorms, superposed epoch analysis, total flux content, auroral oval, IMAGE FUV
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10093502
Downloads since deposit
28Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item