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Title: EFFECTS OF THE NON-RADIAL MAGNETIC FIELD ON MEASURING MAGNETIC HELICITY TRANSPORT ACROSS THE SOLAR PHOTOSPHERE

Abstract

It is generally believed that the evolution of magnetic helicity has a close relationship with solar activity. Before the launch of the Solar Dynamics Observatory (SDO), earlier studies had mostly used Michelson Doppler Imager/SOHO line of sight (LOS) magnetograms and assumed that magnetic fields are radial when calculating the magnetic helicity injection rate from photospheric magnetograms. However, this assumption is not necessarily true. Here we use the vector magnetograms and LOS magnetograms, both taken by the Helioseismic and Magnetic Imager on SDO, to estimate the effects of the non-radial magnetic field on measuring the magnetic helicity injection rate. We find that: (1) the effect of the non-radial magnetic field on estimating tangential velocity is relatively small; (2) when estimating the magnetic helicity injection rate, the effect of the non-radial magnetic field is strong when active regions are observed near the limb and is relatively weak when active regions are close to disk center; and (3) the effect of the non-radial magnetic field becomes minor if the amount of accumulated magnetic helicity is the only concern.

Authors:
;  [1]
  1. Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Road, Chaoyang District, Beijing 100012 (China)
Publication Date:
OSTI Identifier:
22522448
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 804; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; HELICITY; IMAGES; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; PHOTOSPHERE; SOLAR ACTIVITY; STAR EVOLUTION; SUN; VELOCITY

Citation Formats

Song, Y. L., and Zhang, M., E-mail: ylsong@bao.ac.cn. EFFECTS OF THE NON-RADIAL MAGNETIC FIELD ON MEASURING MAGNETIC HELICITY TRANSPORT ACROSS THE SOLAR PHOTOSPHERE. United States: N. p., 2015. Web. doi:10.1088/0004-637X/804/2/102.
Song, Y. L., & Zhang, M., E-mail: ylsong@bao.ac.cn. EFFECTS OF THE NON-RADIAL MAGNETIC FIELD ON MEASURING MAGNETIC HELICITY TRANSPORT ACROSS THE SOLAR PHOTOSPHERE. United States. doi:10.1088/0004-637X/804/2/102.
Song, Y. L., and Zhang, M., E-mail: ylsong@bao.ac.cn. Sun . "EFFECTS OF THE NON-RADIAL MAGNETIC FIELD ON MEASURING MAGNETIC HELICITY TRANSPORT ACROSS THE SOLAR PHOTOSPHERE". United States. doi:10.1088/0004-637X/804/2/102.
@article{osti_22522448,
title = {EFFECTS OF THE NON-RADIAL MAGNETIC FIELD ON MEASURING MAGNETIC HELICITY TRANSPORT ACROSS THE SOLAR PHOTOSPHERE},
author = {Song, Y. L. and Zhang, M., E-mail: ylsong@bao.ac.cn},
abstractNote = {It is generally believed that the evolution of magnetic helicity has a close relationship with solar activity. Before the launch of the Solar Dynamics Observatory (SDO), earlier studies had mostly used Michelson Doppler Imager/SOHO line of sight (LOS) magnetograms and assumed that magnetic fields are radial when calculating the magnetic helicity injection rate from photospheric magnetograms. However, this assumption is not necessarily true. Here we use the vector magnetograms and LOS magnetograms, both taken by the Helioseismic and Magnetic Imager on SDO, to estimate the effects of the non-radial magnetic field on measuring the magnetic helicity injection rate. We find that: (1) the effect of the non-radial magnetic field on estimating tangential velocity is relatively small; (2) when estimating the magnetic helicity injection rate, the effect of the non-radial magnetic field is strong when active regions are observed near the limb and is relatively weak when active regions are close to disk center; and (3) the effect of the non-radial magnetic field becomes minor if the amount of accumulated magnetic helicity is the only concern.},
doi = {10.1088/0004-637X/804/2/102},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 804,
place = {United States},
year = {2015},
month = {5}
}