Proper Orthogonal and Dynamic Mode Decomposition of Sunspot Data

TL;DR

This paper applies Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) to sunspot intensity data to identify dominant magnetohydrodynamic wave modes, specifically sausage and kink modes, in a sunspot's umbra.

Contribution

It demonstrates the combined use of POD and DMD techniques to effectively identify specific MHD wave modes in sunspot observations, advancing analysis methods in solar physics.

Findings

Successfully identified sausage and kink modes in sunspot data

Demonstrated the effectiveness of combined POD and DMD methods

Provided insights into the wave dynamics of sunspot structures

Abstract

High resolution solar observations show the complex structure of the magnetohydrodynamic (MHD) wave motion. We apply the techniques of POD and DMD to identify the dominant MHD wave modes in a sunspot using the intensity time series. The POD technique was used to find modes that are spatially orthogonal, whereas the DMD technique identifies temporal orthogonality. Here we show that the combined POD and DMD approaches can successfully identify both sausage and kink modes in a sunspot umbra with an approximately circular cross-sectional shape.