Magnetohydrodynamic Instabilities of Double Magnetic Bands in a Shallow-water Tachocline Model. II. Teleconnection Between High- and Low-latitude Bands and Across Equator
The “extended solar cycle” indicates that there are two deeply seated toroidal magnetic field bands in each hemisphere. Both bands migrate equatorward as a sunspot cycle progresses. Here, we examine the consequences of global MHD instability of this migrating double-band system in tachocline on the...
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2024-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ad8b50 |
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| author | Mausumi Dikpati Bernadett Belucz Robertus Erdélyi Peter A. Gilman Scott W. McIntosh Breno Raphaldini |
| author_facet | Mausumi Dikpati Bernadett Belucz Robertus Erdélyi Peter A. Gilman Scott W. McIntosh Breno Raphaldini |
| author_sort | Mausumi Dikpati |
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| description | The “extended solar cycle” indicates that there are two deeply seated toroidal magnetic field bands in each hemisphere. Both bands migrate equatorward as a sunspot cycle progresses. Here, we examine the consequences of global MHD instability of this migrating double-band system in tachocline on the latitudinal structure of unstable modes, which are essentially MHD Rossby waves. We find that latitude-location, latitude-separation, and the amplitude of the bands strongly influence the latitudinal structure and growth rates of the unstable modes of both symmetries about the equator. These properties can lead to “teleconnections” between low- and high-latitudes in each hemisphere and across the equator. High-latitude bands can destabilize low-latitude bands that would otherwise be stable. Stronger high-latitude bands lead to strong interactions between low and high latitude in each hemisphere, but inhibit cross-equatorial band-interaction. Strong cross-equatorial interactions of modes can synchronize cycle minima in north and south. Symmetric and antisymmetric modes of similar amplitudes can lead to substantial asymmetries between north and south. As a solar cycle progresses, excited MHD Rossby waves go through a sequence of changes in latitude structure and growth rate, while maintaining strong links in latitude. These changes and links are theoretical evidence of teleconnections between widely separated latitudes and longitudes in the Sun, which may explain many of the evolving surface magnetic patterns observed as a solar cycle progresses. The wider the separation between high- and low-latitude bands, the earlier the cross-equatorial teleconnection starts in a cycle, and hence the earlier the cycle starts declining. |
| format | Article |
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| institution | Kabale University |
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| language | English |
| publishDate | 2024-01-01 |
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| series | The Astrophysical Journal |
| spelling | doaj-art-27f2c806bdb14b6fa36f56767bb5ba622024-12-05T07:43:04ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-0197719910.3847/1538-4357/ad8b50Magnetohydrodynamic Instabilities of Double Magnetic Bands in a Shallow-water Tachocline Model. II. Teleconnection Between High- and Low-latitude Bands and Across EquatorMausumi Dikpati0https://orcid.org/0000-0002-2227-0488Bernadett Belucz1https://orcid.org/0000-0002-0040-1790Robertus Erdélyi2https://orcid.org/0000-0003-3439-4127Peter A. Gilman3https://orcid.org/0000-0002-1639-6252Scott W. McIntosh4https://orcid.org/0000-0002-7369-1776Breno Raphaldini5https://orcid.org/0000-0002-0744-9746High Altitude Observatory , NSF-NCAR, 3080 Center Green Drive, Boulder, CO 80301, USA ; dikpati@ucar.eduSolar Physics and Space Plasma Research Center, School of Mathematics and Statistics, University of Sheffield , S3 7RH, UK; Hungarian Solar Physics Foundation , Gyula, HungarySolar Physics and Space Plasma Research Center, School of Mathematics and Statistics, University of Sheffield , S3 7RH, UK; Hungarian Solar Physics Foundation , Gyula, Hungary; Department of Astronomy, Institute of Geography and Earth Sciences, Eötvös University , Budapest, HungaryHigh Altitude Observatory , NSF-NCAR, 3080 Center Green Drive, Boulder, CO 80301, USA ; dikpati@ucar.eduHigh Altitude Observatory , NSF-NCAR, 3080 Center Green Drive, Boulder, CO 80301, USA ; dikpati@ucar.edu; Lynker Space , Boulder, CO 80301, USAHigh Altitude Observatory , NSF-NCAR, 3080 Center Green Drive, Boulder, CO 80301, USA ; dikpati@ucar.eduThe “extended solar cycle” indicates that there are two deeply seated toroidal magnetic field bands in each hemisphere. Both bands migrate equatorward as a sunspot cycle progresses. Here, we examine the consequences of global MHD instability of this migrating double-band system in tachocline on the latitudinal structure of unstable modes, which are essentially MHD Rossby waves. We find that latitude-location, latitude-separation, and the amplitude of the bands strongly influence the latitudinal structure and growth rates of the unstable modes of both symmetries about the equator. These properties can lead to “teleconnections” between low- and high-latitudes in each hemisphere and across the equator. High-latitude bands can destabilize low-latitude bands that would otherwise be stable. Stronger high-latitude bands lead to strong interactions between low and high latitude in each hemisphere, but inhibit cross-equatorial band-interaction. Strong cross-equatorial interactions of modes can synchronize cycle minima in north and south. Symmetric and antisymmetric modes of similar amplitudes can lead to substantial asymmetries between north and south. As a solar cycle progresses, excited MHD Rossby waves go through a sequence of changes in latitude structure and growth rate, while maintaining strong links in latitude. These changes and links are theoretical evidence of teleconnections between widely separated latitudes and longitudes in the Sun, which may explain many of the evolving surface magnetic patterns observed as a solar cycle progresses. The wider the separation between high- and low-latitude bands, the earlier the cross-equatorial teleconnection starts in a cycle, and hence the earlier the cycle starts declining.https://doi.org/10.3847/1538-4357/ad8b50Solar activityMagnetohydrodynamicsSolar interiorSolar photosphereSolar cycle |
| spellingShingle | Mausumi Dikpati Bernadett Belucz Robertus Erdélyi Peter A. Gilman Scott W. McIntosh Breno Raphaldini Magnetohydrodynamic Instabilities of Double Magnetic Bands in a Shallow-water Tachocline Model. II. Teleconnection Between High- and Low-latitude Bands and Across Equator The Astrophysical Journal Solar activity Magnetohydrodynamics Solar interior Solar photosphere Solar cycle |
| title | Magnetohydrodynamic Instabilities of Double Magnetic Bands in a Shallow-water Tachocline Model. II. Teleconnection Between High- and Low-latitude Bands and Across Equator |
| title_full | Magnetohydrodynamic Instabilities of Double Magnetic Bands in a Shallow-water Tachocline Model. II. Teleconnection Between High- and Low-latitude Bands and Across Equator |
| title_fullStr | Magnetohydrodynamic Instabilities of Double Magnetic Bands in a Shallow-water Tachocline Model. II. Teleconnection Between High- and Low-latitude Bands and Across Equator |
| title_full_unstemmed | Magnetohydrodynamic Instabilities of Double Magnetic Bands in a Shallow-water Tachocline Model. II. Teleconnection Between High- and Low-latitude Bands and Across Equator |
| title_short | Magnetohydrodynamic Instabilities of Double Magnetic Bands in a Shallow-water Tachocline Model. II. Teleconnection Between High- and Low-latitude Bands and Across Equator |
| title_sort | magnetohydrodynamic instabilities of double magnetic bands in a shallow water tachocline model ii teleconnection between high and low latitude bands and across equator |
| topic | Solar activity Magnetohydrodynamics Solar interior Solar photosphere Solar cycle |
| url | https://doi.org/10.3847/1538-4357/ad8b50 |
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