Revisiting the solar tachocline: Average properties and temporal variations

TL;DR

This study analyzes over a solar cycle's data to investigate the average properties and temporal variations of the solar tachocline, revealing its complex shape and dynamic behavior.

Contribution

It provides a detailed analysis of the tachocline's average structure and its time-dependent variations using two-dimensional modeling of observational data.

Findings

The tachocline is prolate in shape.

It is thicker at higher latitudes.

Some properties, like the rotation transition, vary over time.

Abstract

The tachocline is believed to be the region where the solar dynamo operates. With over a solar cycle's worth of data available from the MDI and GONG instruments, we are in a position to investigate not merely the average structure of the solar tachocline, but also its time variations. We determine the properties of the tachocline as a function of time by fitting a two-dimensional model that takes latitudinal variations of the tachocline properties into account. We confirm that if we consider central position of the tachocline, it is prolate. Our results show that the tachocline is thicker at higher latitudes than the equator, making the overall shape of the tachocline more complex. Of the tachocline properties examined, the transition of the rotation rate across the tachocline, and to some extent the position of the tachocline, show some temporal variations.