Is Solar Minimum 24/25 Another Unusual One?

TL;DR

This study compares the solar minimum 24/25 with previous minima, analyzing magnetic fields, corona morphology, and solar wind to determine its uniqueness and the recovery of typical features.

Contribution

It provides a detailed analysis showing that solar minimum 24/25 is only partially unusual and highlights the role of polar field enhancement in feature recovery.

Findings

The corona morphology was more complex than a simple dipole before the minimum.

Fast solar wind streams were less dominant than in minimum 23/24.

IMF strength, density, and mass flux increased but did not reach previous minimum levels.

Abstract

The solar minimum 23/24 is considered to be unusual because it exhibits features that differ notably from those commonly seen in pervious minima. In this letter, we analyze the solar polar magnetic field, the potential-field solution of the solar corona, and the in-situ solar wind measurements to see whether the recent solar minimum 24/25 is another unusual one. While the dipolar configuration that are commonly seen during minimum 22/23 and earlier minima persist for about half a year after the absolute minimum of solar cycle 24, the corona has a morphology more complex than a simple dipole before the absolute minimum. The fast solar wind streams are less dominant than minimum 23/24. The IMF strength, density and mass flux that are historically low in the minimum 23/24 are regained during minimum 24/25, but still do not reach the minimum 22/23 level. From the analysis of this Letter, it seems that the minimum 24/25 is only partially unusual, and the recovery of the commonly minimum features may result from the enhancement of the polar field.