Preprints
https://doi.org/10.5194/egusphere-2022-296
https://doi.org/10.5194/egusphere-2022-296
13 May 2022
 | 13 May 2022

The Morphology of Poleward Moving Auroral Forms

Anton Oscar Goertz, Noora Partamies, Daniel Whiter, and Lisa Baddeley

Abstract. We investigated the morphology of poleward moving auroral forms (PMAFs) qualitatively by visual inspection of all sky camera (ASC) images and quantitatively using the arciness index. The PMAFs in this study were initially identified with a meridian scanning photometer located at Kjell Henriksen Observatory (KHO), Svalbard, and analyzed using ASC images taken by cameras at KHO and in Ny-Ålesund, Svalbard. We present a detailed six-step evolution of PMAF morphology in two dimensions. This evolution includes (1) an equatorward expansion of the auroral oval and an intensification of auroral brightness at the open-closed boundary, (2) the appearance of an arc-like structure in the oval, (3) poleward and possible west/eastward propagation, (4) azimuthal expansion events, (5) rebrightening of the PMAF and eventual (6) fading away. While there have been previous studies commenting on PMAF morphology this is the first work dedicated to the morphological evolution of PMAFs and it includes more detailed discussion and novel aspects, such as the observation of initial merging of 557.7 nm auroral patches to form a PMAF. Moreover, the morphology of PMAFs is quantified using the arciness index, which is a number describing how arc-like auroral forms appear in ASC images. We present the results of a superposed epoch analysis of arciness in relation to PMAF occurrence. This analysis uncovered that arciness increases suddenly during the onset of a PMAF event and decreases over the PMAF lifetime to return to its baseline value once the event has concluded. This behavior may be understood based on changes in the morphology of PMAFs and the auroral oval and furthermore may be used to identify PMAFs from arciness data.

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Journal article(s) based on this preprint

21 Mar 2023
Morphological evolution and spatial profile changes of poleward moving auroral forms
Anton Goertz, Noora Partamies, Daniel Whiter, and Lisa Baddeley
Ann. Geophys., 41, 115–128, https://doi.org/10.5194/angeo-41-115-2023,https://doi.org/10.5194/angeo-41-115-2023, 2023
Short summary
Anton Oscar Goertz, Noora Partamies, Daniel Whiter, and Lisa Baddeley

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-296', Anonymous Referee #1, 06 Jun 2022
    • AC2: 'Reply on RC1', Anton Goertz, 25 Aug 2022
      • AC3: 'Reply on AC2', Anton Goertz, 09 Dec 2022
  • RC2: 'Comment on egusphere-2022-296', Anonymous Referee #2, 27 Jun 2022
    • AC1: 'Reply on RC2', Anton Goertz, 25 Aug 2022

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-296', Anonymous Referee #1, 06 Jun 2022
    • AC2: 'Reply on RC1', Anton Goertz, 25 Aug 2022
      • AC3: 'Reply on AC2', Anton Goertz, 09 Dec 2022
  • RC2: 'Comment on egusphere-2022-296', Anonymous Referee #2, 27 Jun 2022
    • AC1: 'Reply on RC2', Anton Goertz, 25 Aug 2022

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
ED: Publish subject to revisions (further review by editor and referees) (21 Sep 2022) by Dalia Buresova
AR by Anton Goertz on behalf of the Authors (08 Oct 2022)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (24 Oct 2022) by Dalia Buresova
RR by Anonymous Referee #2 (26 Nov 2022)
RR by Anonymous Referee #1 (13 Dec 2022)
ED: Publish subject to minor revisions (review by editor) (15 Dec 2022) by Dalia Buresova
AR by Anton Goertz on behalf of the Authors (20 Dec 2022)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (28 Dec 2022) by Dalia Buresova
AR by Anton Goertz on behalf of the Authors (23 Jan 2023)  Manuscript 

Journal article(s) based on this preprint

21 Mar 2023
Morphological evolution and spatial profile changes of poleward moving auroral forms
Anton Goertz, Noora Partamies, Daniel Whiter, and Lisa Baddeley
Ann. Geophys., 41, 115–128, https://doi.org/10.5194/angeo-41-115-2023,https://doi.org/10.5194/angeo-41-115-2023, 2023
Short summary
Anton Oscar Goertz, Noora Partamies, Daniel Whiter, and Lisa Baddeley
Anton Oscar Goertz, Noora Partamies, Daniel Whiter, and Lisa Baddeley

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Short summary
Poleward moving auroral forms (PMAFs) are specific types of aurora that are believed to be the signature of the connection of Earth's magnetic field to that of the sun. In this paper we discuss the evolution of PMAFs in regards to their auroral morphology as observed in all-sky camera images. We interpret different aspects of this evolution in terms of the connection dynamics between Earth's and the sun's magnetic fields. This sheds more light on the magnetic interaction between sun and Earth.