Segmentation of Coronal Holes Using Active Contours Without Edges

TL;DR

This paper presents a novel active contour method for segmenting coronal holes in EUV solar images that does not rely on fixed intensity thresholds, improving robustness and consistency across datasets.

Contribution

The paper introduces an active contour segmentation approach that detects coronal holes without predefined intensity thresholds, enhancing robustness across various data types and resolutions.

Findings

Segmentation results align with magnetic regions and solar wind data.

Method matches other segmentation techniques qualitatively.

Robustness across different datasets and image qualities.

Abstract

An application of active contours without edges is presented as an efficient and effective means of extracting and characterizing coronal holes. Coronal holes are regions of low-density plasma on the Sun with open magnetic field lines. As the source of the fast solar wind, the detection and characterization of these regions is important for both testing theories of their formation and evolution and from a space weather perspective. Coronal holes are detected in full disk extreme ultraviolet (EUV) images of the corona obtained with the Solar Dynamics Observatory Atmospheric Imaging Assembly (SDO/AIA). The proposed method detects coronal boundaries without determining any fixed intensity value in the data. Instead, the active contour segmentation employs an energy-minimization in which coronal holes are assumed to have more homogeneous intensities than surrounding active regions and quiet Sun. The segmented coronal holes tend to correspond to unipolar magnetic regions, are consistent with concurrent solar wind observations, and qualitatively match the coronal holes segmented by other methods. The means to identify a coronal hole without specification of a final intensity threshold may allow this algorithm to be more robust across multiple datasets, regardless of data type, resolution, and quality.