The CHASM-SWPC Dataset for Coronal Hole Detection & Analysis

TL;DR

This paper introduces the CHASM-SWPC dataset for coronal hole detection, developed through semi-automatic annotation of solar EUV maps, and demonstrates improved neural network performance using this dataset.

Contribution

The paper presents a new high-quality dataset and annotation tool for coronal hole detection, along with enhanced neural network models trained on this data.

Findings

Neural networks trained on CHASM-SWPC achieved 0.9805 accuracy.

The dataset enabled better model performance than previous pretrained models.

The CHASM tool facilitated rapid and accurate annotation of solar maps.

Abstract

Coronal holes (CHs) are low-activity, low-density solar coronal regions with open magnetic field lines (Cranmer 2009). In the extreme ultraviolet (EUV) spectrum, CHs appear as dark patches. Using daily hand-drawn maps from the Space Weather Prediction Center (SWPC), we developed a semi-automated pipeline to digitize the SWPC maps into binary segmentation masks. The resulting masks constitute the CHASM-SWPC dataset, a high-quality dataset to train and test automated CH detection models, which is released with this paper. We developed CHASM (Coronal Hole Annotation using Semi-automatic Methods), a software tool for semi-automatic annotation that enables users to rapidly and accurately annotate SWPC maps. The CHASM tool enabled us to annotate 1,111 CH masks, comprising the CHASM-SWPC-1111 dataset. We then trained multiple CHRONNOS (Coronal Hole RecOgnition Neural Network Over multi-Spectral-data) architecture (Jarolim et al. 2021) neural networks using the CHASM-SWPC dataset and compared their performance. Training the CHRONNOS neural network on these data achieved an accuracy of 0.9805, a True Skill Statistic (TSS) of 0.6807, and an intersection-over-union (IoU) of 0.5668, which is higher than the original pretrained CHRONNOS model Jarolim et al. (2021) achieved an accuracy of 0.9708, a TSS of 0.6749, and an IoU of 0.4805, when evaluated on the CHASM-SWPC-1111 test set.