TY - JOUR
T1 - The Recent Anomalously Weak Polar Field Does Not Imply a Weak Field at Solar Cycle 25 Minimum
AU - Wang, Zi Fan
AU - Jiang, Jie
AU - Luo, Yukun
AU - Wang, Ruihui
AU - Ma, Xinchun
AU - Wang, Jing Xiu
N1 - Publisher Copyright:
© 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
PY - 2026/8/1
Y1 - 2026/8/1
N2 - The ongoing solar cycle 25 has progressed past its peak of sunspot numbers, being stronger than the previous cycle 24. However, the present polar field is rather weak compared to previous cycles at the same evolution phase, particularly in the northern hemisphere, where it has been decreasing since mid-2025. A prominent poleward surge is observed to cause the decrease of the polar field. This raises concerns for the polar field at cycle 25 minimum, which is the precursor to the strength of the next cycle, cycle 26. To predict whether the polar field at cycle 25 minimum will be weak as expected, we use observation-based statistical properties to predict the active region emergence during the latter half of cycle 25 and use a surface flux transport model to simulate the evolution of the large-scale magnetic field. We predict the polar field at cycle 25 minimum to be −5.62 ± 1.61 G in the north and 5.51 ± 1.48 G in the south, both stronger than those at cycle 24 minimum. This is because the poleward surge causing the temporal decrease of the polar field originates from a group of active regions that produces net increase to the polar field, instead of active regions with non-Joy tilt. Our results suggest the weak polar field at present is unlikely to cause a weak minimum and an exceptionally weak cycle 26, clarifying that the short-term evolution should not be simply correlated with the long-term properties of the solar large-scale field.
AB - The ongoing solar cycle 25 has progressed past its peak of sunspot numbers, being stronger than the previous cycle 24. However, the present polar field is rather weak compared to previous cycles at the same evolution phase, particularly in the northern hemisphere, where it has been decreasing since mid-2025. A prominent poleward surge is observed to cause the decrease of the polar field. This raises concerns for the polar field at cycle 25 minimum, which is the precursor to the strength of the next cycle, cycle 26. To predict whether the polar field at cycle 25 minimum will be weak as expected, we use observation-based statistical properties to predict the active region emergence during the latter half of cycle 25 and use a surface flux transport model to simulate the evolution of the large-scale magnetic field. We predict the polar field at cycle 25 minimum to be −5.62 ± 1.61 G in the north and 5.51 ± 1.48 G in the south, both stronger than those at cycle 24 minimum. This is because the poleward surge causing the temporal decrease of the polar field originates from a group of active regions that produces net increase to the polar field, instead of active regions with non-Joy tilt. Our results suggest the weak polar field at present is unlikely to cause a weak minimum and an exceptionally weak cycle 26, clarifying that the short-term evolution should not be simply correlated with the long-term properties of the solar large-scale field.
KW - Solar cycle (1487)
UR - https://www.scopus.com/pages/publications/105046218237
U2 - 10.3847/2041-8213/ae8765
DO - 10.3847/2041-8213/ae8765
M3 - 文章
AN - SCOPUS:105046218237
SN - 2041-8205
VL - 1006
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L33
ER -