# Statistical study of solar dimmings using CoDiT

## TL;DR

This study analyzes 154 solar dimmings using a novel detection algorithm to understand their properties and relationship with flares and CMEs, revealing correlations between dimming size, magnetic flux, and eruption energy.

## Contribution

Introduces a new coronal hole detection method applied to EUV images, enabling detailed analysis of dimming footpoints and their role in CME structure and dynamics.

## Key findings

- Larger dimmings are longer-lived.
- Smaller dimmings have higher magnetic flux imbalance.
- Dimming EUV intensity correlates with plasma removal and eruption energy.

## Abstract

We present the results from analyzing the physical and morphological properties of 154 dimmings (transient coronal holes) and the associated flares and coronal mass ejections (CMEs). Each dimming in our 2013 catalog was processed with the semi-automated Coronal Dimming Tracker using Solar Dynamics Observatory AIA 193 A observations and HMI magnetograms. Instead of the typically used difference images, we used our coronal hole detection algorithm to detect transient dark regions "directly" in extreme ultraviolet (EUV) images. This allowed us to study dimmings as the footpoints of CMEs - in contrast with the larger, diffuse dimmings seen in difference images that represent the projected view of the rising, expanding plasma. Studying the footpoint-dimming morphology allowed us to better understand the CME structure in the low corona. While comparing the physical properties of dimmings, flares, and CMEs we were also able to identify relationships between the different parts of this complex eruptive phenomenon. We found that larger dimmings are longer-lived, suggesting that it takes longer to "close down" large open magnetic regions. Also, during their growth phase, smaller dimmings acquire a higher magnetic flux imbalance (i. e., become more unipolar) than larger dimmings. Furthermore, we found that the EUV intensity of dimmings (indicative of local electron density) correlates with how much plasma was removed and how energetic the eruption was. Studying the morphology of dimmings (single, double, fragmented) also helped us identify different configurations of the quasi-open magnetic field.