Comparison of coronal extrapolation methods for cycle 24 using HMI data

Arden, William and Norton, Aimee and Sun, Xudong and Zhao, Xuepu (2016) Comparison of coronal extrapolation methods for cycle 24 using HMI data. The Astrophysical Journal, 823 (1). ISSN 0004-637X

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Abstract

Two extrapolation models of the solar coronal magnetic field are compared using magnetogram data from the SDO/HMI instrument. The two models, a horizontal current-current sheet-source surface (HCCSSS) model and a potential
field-source surface (PFSS) model differ in their treatment of coronal currents.
Each model has its own critical variable, respectively the radius of a cusp surface and a source surface, and it is found that adjusting these heights over the period studied allows better fit between the models and the solar open
flux at 1 AU as calculated from the Interplanetary Magnetic Field (IMF). The HCCSSS model provides the better fit for the overall period from 2010 November to 2015 May as well as for two subsets of the period - the minimum/rising part of the solar cycle, and the recently-identified peak in the IMF from mid-2014 to mid-2015 just after solar maximum. It is found that a HCCSSS cusp surface height of 1.7 Rs provides the best fit to the IMF for the overall period, while 1.7 & 1.9 Rs give the best fits for the two subsets. The corresponding values for the PFSS source surface height are 2.1, 2.2 and 2.0 Rs respectively. This means that the
HCCSSS cusp surface rises as the solar cycle progresses while the PFSS source surface falls.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version made accessible, in accordance with the copyright policy of the publisher.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences
Date Deposited: 05 May 2016 00:36
Last Modified: 24 Mar 2017 02:46
Uncontrolled Keywords: solar cycle, solar corona
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020109 Space and Solar Physics
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.3847/0004-637X/823/1/21
URI: http://eprints.usq.edu.au/id/eprint/29107

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