Limitations of absolute current densities derived from the Semel &; Skumanich method |
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Authors: | Jing Li and YuHong Fan |
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Institution: | 1.Institute for Astronomy,University of Hawaii,Honolulu,USA;2.High Altitude Observatory, Earth and Sun Systems Laboratory,National Center for Atmospheric Research,Boulder,USA |
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Abstract: | Semel and Skumanich proposed a method to obtain the absolute electric current density, |J
z
|, without disambiguation of 180° in the transverse field directions. The advantage of the method is that the uncertainty
in the determination of the ambiguity in the magnetic azimuth is removed. Here, we investigate the limits of the calculation
when applied to a numerical MHD model. We have found that the combination of changes in the magnetic azimuth with vanishing
horizontal field component leads to errors, where electric current densities are often strong. Where errors occur, the calculation
gives |J
z
| too small by factors typically 1.2–2.0. |
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Keywords: | |
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