Is Solar Minimum 24/25 Another Unusual One?

Huichao Li, Xueshang Feng, Fengsi Wei

Published 2021-07-11Version 1

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.