Signatures of Solar Cycle 25 in Subsurface Zonal Flows

TL;DR

This study analyzes nearly two solar cycles of helioseismic data to identify signatures of Solar Cycle 25 in subsurface zonal flows, predicting its onset around mid-2019 based on flow patterns.

Contribution

It provides the first observational evidence of the mid-latitude acceleration pattern associated with Cycle 25 using continuous helioseismic data.

Findings

Detection of mid-latitude acceleration indicative of Cycle 25

Flow patterns suggest the cycle's onset around mid-2019

First to link helioseismic flows with Cycle 25 predictions

Abstract

The pattern of migrating zonal flow bands associated with the solar cycle, known as the torsional oscillation, has been monitored with continuous global helioseismic observations by the Global Oscillations Network Group, together with those made by the Michelson Doppler Imager onboard the Solar and Heliosepheric Observatory and its successor the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory, since 1995, giving us nearly two full solar cycles of observations. We report that the flows now show traces of the mid-latitude acceleration that is expected to become the main equatorward-moving branch of the zonal flow pattern for Cycle 25. Based on the current position of this branch, we speculate that the onset of widespread activity for Cycle 25 is unlikely to be earlier than the middle of 2019.