Homogenising SoHO/EIT and SDO/AIA 171\AA$~$ Images: A Deep Learning Approach

TL;DR

This paper develops a deep learning ensemble approach to homogenize EUV solar images from different instruments over two solar cycles, improving data consistency for space weather prediction.

Contribution

It introduces an ensemble of deep learning models with Bayesian uncertainty estimation to create a unified EUV solar image dataset from multiple surveys.

Findings

Ensemble uncertainty decreases with larger training data.

Uncertainty highlights poorly represented test data.

Method achieves homogeneous EUV images across instruments.

Abstract

Extreme Ultraviolet images of the Sun are becoming an integral part of space weather prediction tasks. However, having different surveys requires the development of instrument-specific prediction algorithms. As an alternative, it is possible to combine multiple surveys to create a homogeneous dataset. In this study, we utilize the temporal overlap of SoHO/EIT and SDO/AIA 171~\AA ~surveys to train an ensemble of deep learning models for creating a single homogeneous survey of EUV images for 2 solar cycles. Prior applications of deep learning have focused on validating the homogeneity of the output while overlooking the systematic estimation of uncertainty. We use an approach called `Approximate Bayesian Ensembling' to generate an ensemble of models whose uncertainty mimics that of a fully Bayesian neural network at a fraction of the cost. We find that ensemble uncertainty goes down as the training set size increases. Additionally, we show that the model ensemble adds immense value to the prediction by showing higher uncertainty in test data that are not well represented in the training data.