Is Solar Minimum 24/25 Another Unusual One?

Abstract

Abstract Solar minimum 23/24 is considered to be unusual because it exhibits features that differ notably from those commonly seen in previous 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 if the recent solar minimum 24/25 is another unusual one. While the dipolar configuration that is 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 that is more complex than a simple dipole before the absolute minimum. The fast solar wind streams are less dominant than minimum 23/24. The interplanetary magnetic field 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 partly unusual, and the recovery of the commonly minimum features may result from the enhancement of the polar field.