Latitude-Dependent Time Variations of the Solar Tachocline

Fuente: arXiv
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Autori principali: Basu, Sarbani, Korzennik, Sylvain G., Tripathy, Sushanta C.
Natura: Preprint
Pubblicazione: 2026
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author Basu, Sarbani
Korzennik, Sylvain G.
Tripathy, Sushanta C.
author_facet Basu, Sarbani
Korzennik, Sylvain G.
Tripathy, Sushanta C.
contents We have examined how the characteristics of the tachocline -- i.e., the change in rotation rate $δΩ$, or the "jump", the position of the midpoint of the tachocline, $r_d$, and the width of the tachocline, $w_d$, -- change as a function of time at different latitudes using 30 years of helioseismic data obtained by the GONG network. We find a statistically significant change in the jump, however, these changes do not have a simple correlation with solar activity. The dependence is different for solar Cycles 23 and 24, and for Cycle 25, it is more similar to that of Cycle 24. While our measured changes of the tachocline's width with time are marginally statistically significant, {the cross correlation is statistically significant and implies that the width is larger when the solar activity is smaller, suggesting that magnetic fields play a role in confining the tachocline. The position of the tachocline shows a significant secular change at low latitudes ($< \simeq 50^\circ$).} At these latitudes, the tachocline has been moving steadily closer to the base of the convection zone. This is consistent with other measurements that have shown that the overall complexity of solar activity has been decreasing over the last few decades. It leads us to speculate that strong magnetic fields tend to push the tachocline deeper into the radiative zone.
format Preprint
id arxiv_https___arxiv_org_abs_2603_02321
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Latitude-Dependent Time Variations of the Solar Tachocline
Basu, Sarbani
Korzennik, Sylvain G.
Tripathy, Sushanta C.
Solar and Stellar Astrophysics
We have examined how the characteristics of the tachocline -- i.e., the change in rotation rate $δΩ$, or the "jump", the position of the midpoint of the tachocline, $r_d$, and the width of the tachocline, $w_d$, -- change as a function of time at different latitudes using 30 years of helioseismic data obtained by the GONG network. We find a statistically significant change in the jump, however, these changes do not have a simple correlation with solar activity. The dependence is different for solar Cycles 23 and 24, and for Cycle 25, it is more similar to that of Cycle 24. While our measured changes of the tachocline's width with time are marginally statistically significant, {the cross correlation is statistically significant and implies that the width is larger when the solar activity is smaller, suggesting that magnetic fields play a role in confining the tachocline. The position of the tachocline shows a significant secular change at low latitudes ($< \simeq 50^\circ$).} At these latitudes, the tachocline has been moving steadily closer to the base of the convection zone. This is consistent with other measurements that have shown that the overall complexity of solar activity has been decreasing over the last few decades. It leads us to speculate that strong magnetic fields tend to push the tachocline deeper into the radiative zone.
title Latitude-Dependent Time Variations of the Solar Tachocline
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2603.02321