The Sun’s Magnetic Power Spectra over Two Solar Cycles. I. Calibration between SDO/HMI and SOHO/MDI Magnetograms
The Sun’s magnetic field is strongly structured over a broad range of scales. Magnetic spatial power spectral analysis provides a powerful tool for understanding the various scales of magnetic fields and their interactions with plasma motions. We aim to investigate the power spectra using spherical...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acec77 |
| _version_ | 1797690741350203392 |
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| author | Yukun Luo Jie Jiang Ruihui Wang |
| author_facet | Yukun Luo Jie Jiang Ruihui Wang |
| author_sort | Yukun Luo |
| collection | DOAJ |
| description | The Sun’s magnetic field is strongly structured over a broad range of scales. Magnetic spatial power spectral analysis provides a powerful tool for understanding the various scales of magnetic fields and their interactions with plasma motions. We aim to investigate the power spectra using spherical harmonic decomposition of high-resolution Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) and Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI) synoptic magnetograms covering three consecutive solar cycle minima, in a series of papers. As the first of the series, we calibrate and analyze the power spectra based on cotemporal SDO/HMI and SOHO/MDI data in this paper. For the first time, we find that the calibration factor r between SOHO/MDI and SDO/HMI varies with the spatial scale l of the magnetic field, where l is the degree of the spherical harmonic. The calibration factor satisfies $r(l)=\sqrt{-0.021{l}^{0.64}+2}\quad (5\lt {\rm{l}}\leqslant 539)$ . With the calibration function, most contemporaneous SOHO/MDI and SDO/HMI magnetograms show consistent power spectra from about 8 Mm to the global scales over about three orders of magnitude. Moreover, magnetic power spectra from SOHO/MDI and SDO/HMI maps show peaks/knees at l ≈ 120, corresponding to the typical supergranular scale (about 35 Mm) constrained from direct velocimetric measurements. This study paves the way for investigating the solar cycle dependence of supergranulation and magnetic power spectra in subsequent studies. |
| first_indexed | 2024-03-12T02:03:29Z |
| format | Article |
| id | doaj.art-afcf9e522ac444a4bf41564fcc93794f |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T02:03:29Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-afcf9e522ac444a4bf41564fcc93794f2023-09-07T09:12:01ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-01954219910.3847/1538-4357/acec77The Sun’s Magnetic Power Spectra over Two Solar Cycles. I. Calibration between SDO/HMI and SOHO/MDI MagnetogramsYukun Luo0https://orcid.org/0000-0002-6977-1239Jie Jiang1https://orcid.org/0000-0001-5002-0577Ruihui Wang2https://orcid.org/0000-0003-0256-8102School of Space and Environment, Beihang University , Beijing, People’s Republic of China; Key Laboratory of Space Environment Monitoring and Information Processing of MIIT , Beijing, People’s Republic of ChinaSchool of Space and Environment, Beihang University , Beijing, People’s Republic of China; Key Laboratory of Space Environment Monitoring and Information Processing of MIIT , Beijing, People’s Republic of ChinaSchool of Space and Environment, Beihang University , Beijing, People’s Republic of China; Key Laboratory of Space Environment Monitoring and Information Processing of MIIT , Beijing, People’s Republic of ChinaThe Sun’s magnetic field is strongly structured over a broad range of scales. Magnetic spatial power spectral analysis provides a powerful tool for understanding the various scales of magnetic fields and their interactions with plasma motions. We aim to investigate the power spectra using spherical harmonic decomposition of high-resolution Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) and Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI) synoptic magnetograms covering three consecutive solar cycle minima, in a series of papers. As the first of the series, we calibrate and analyze the power spectra based on cotemporal SDO/HMI and SOHO/MDI data in this paper. For the first time, we find that the calibration factor r between SOHO/MDI and SDO/HMI varies with the spatial scale l of the magnetic field, where l is the degree of the spherical harmonic. The calibration factor satisfies $r(l)=\sqrt{-0.021{l}^{0.64}+2}\quad (5\lt {\rm{l}}\leqslant 539)$ . With the calibration function, most contemporaneous SOHO/MDI and SDO/HMI magnetograms show consistent power spectra from about 8 Mm to the global scales over about three orders of magnitude. Moreover, magnetic power spectra from SOHO/MDI and SDO/HMI maps show peaks/knees at l ≈ 120, corresponding to the typical supergranular scale (about 35 Mm) constrained from direct velocimetric measurements. This study paves the way for investigating the solar cycle dependence of supergranulation and magnetic power spectra in subsequent studies.https://doi.org/10.3847/1538-4357/acec77SupergranulationSolar photosphereCalibrationSolar magnetic fields |
| spellingShingle | Yukun Luo Jie Jiang Ruihui Wang The Sun’s Magnetic Power Spectra over Two Solar Cycles. I. Calibration between SDO/HMI and SOHO/MDI Magnetograms The Astrophysical Journal Supergranulation Solar photosphere Calibration Solar magnetic fields |
| title | The Sun’s Magnetic Power Spectra over Two Solar Cycles. I. Calibration between SDO/HMI and SOHO/MDI Magnetograms |
| title_full | The Sun’s Magnetic Power Spectra over Two Solar Cycles. I. Calibration between SDO/HMI and SOHO/MDI Magnetograms |
| title_fullStr | The Sun’s Magnetic Power Spectra over Two Solar Cycles. I. Calibration between SDO/HMI and SOHO/MDI Magnetograms |
| title_full_unstemmed | The Sun’s Magnetic Power Spectra over Two Solar Cycles. I. Calibration between SDO/HMI and SOHO/MDI Magnetograms |
| title_short | The Sun’s Magnetic Power Spectra over Two Solar Cycles. I. Calibration between SDO/HMI and SOHO/MDI Magnetograms |
| title_sort | sun s magnetic power spectra over two solar cycles i calibration between sdo hmi and soho mdi magnetograms |
| topic | Supergranulation Solar photosphere Calibration Solar magnetic fields |
| url | https://doi.org/10.3847/1538-4357/acec77 |
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