Abstract Details
| Name: Susanta Kumar Bisoi Affiliation: National Institute of Technology Rourkela Conference ID: ASI2025_720 Title : Inner-heliospheric signatures of steadily declining solar magnetic fields and their possible implications Authors and Co-Authors : Susanta Kumar Bisoi, Harsha Avinash Tanti, Abhirup Datta, and K. Fujiki Abstract Type : Poster Abstract Category : Sun, Solar System, Exoplanets, and Astrobiology Abstract : We have examined solar photospheric magnetic fields for the solar cycles 21-25, covering the period 1975-2024. The unsigned photospheric magnetic fields at low latitudes (0-45 degrees), known as solar toroidal fields, have shown a solar cycle variation, with the field strength being stronger during the maximum of cycle 25 than during the maximum of cycle 24. However, the unsigned field strength of photospheric magnetic fields at high latitudes (45-78 degrees), known as solar polar fields, has shown a significant steady decline since the mid-1990s. The unsigned field strength of solar polar fields, after an increase during 2015-2020, declined again until 2024, continuing the declining trend for a long 30 years. Also, we have examined the solar wind microturbulence levels in the inner heliosphere (0.2-0.8 AU), using interplanetary scintillation observations at 327 MHz, covering the period 1983-2022, that has steadily declined since the mid-1990s and continued until 2022, synchronously with the solar polar fields. We have found that the floor level in both solar toroidal fields and solar wind magnetic fields has been reduced during the minimum of cycle 23 and recovered back during the minimum of cycle 24. In addition, a hemispherically asymmetric solar polar reversal was evident in the signed (axial) solar polar fields during cycles 21-25, with the reversal in cycle 25 for the northern hemisphere already completed. Still, the same for the southern hemisphere is yet to be completed. We discuss the implications of such a long declining trend and other anomalies in solar cycle activities during the solar cycles 21-25. |