Photospheric Velocities Measured at Mt. Wilson Show Zonal and Sectoral Flows Compose the Torsional Oscillations

TL;DR

This study analyzes 30 years of Mt. Wilson solar velocity data, revealing that both zonal and sectoral flows contribute to torsional oscillations, emphasizing the importance of including both components in models.

Contribution

Introduces a new method for measuring North/South and East/West velocities from Mt. Wilson data and demonstrates their combined role in torsional oscillations.

Findings

Residual flow deviations are synchronized and match torsional oscillations.

Both zonal and sectoral flows are essential for modeling torsional oscillations.

Data from 1983 to 2013 confirms the flow components' significance.

Abstract

The methods for reducing the observations from the 150-foot Tower Telescope on Mt.~Wilson are reviewed and a new method for determining the North/South (sectoral) and the East/West (zonal) velocity components is described and applied. Due to a calibration problem with the data prior to 1983, only observations between 1983 and 2013 are presented at this time. After subtraction of latitude dependent averages over the 30-year period of observation the residual deviations in the sectoral and zonal flow velocities are well synchronized and correspond to what is widely recognized as the Torsional Oscillations. Both flow components need to be included in any model that replicates the Torsional Oscillations.