Reconstructing Synthetic SDO/AIA 193 A EUV Images from He I 10830 A Observations with Diffusion Model Translator

2026-06-07

AI Summary

This study addresses the scarcity of extreme ultraviolet (EUV) coronal observations prior to the EUV imaging era, which has hindered investigations into long-term, large-scale coronal evolution. To overcome this limitation, the authors propose a coronal hole–aware diffusion model (CH-aware DMT), the first application of conditional diffusion-based image translation to synthesize physically plausible SDO/AIA 193 Å EUV images from historical He I 10830 Å observations. Trained on co-registered SOLIS and AIA data and incorporating coronal hole priors, the model’s generalization capability is validated using a monthly stratified evaluation strategy. Experimental results demonstrate high fidelity between reconstructed and actual EUV images (full-disk correlation coefficient CC = 0.92; coronal hole region CC = 0.84). The method successfully extends EUV-like coronal reconstructions back to 1974, showing strong agreement with SOHO/EIT, Yohkoh/SXT observations, and solar activity indices, thereby substantially expanding the temporal coverage of EUV coronal data.

Abstract

Routine full-disk EUV imaging has been available only since the modern era, such as SOHO and SDO. To extend EUV coronal context into earlier periods, we leverage the multi-decade availability of full-disk \HeI{} observations, whose absorption is modulated by coronal irradiance and magnetic topology and is widely used as a proxy for open-field regions. We present a diffusion-based conditional image translation framework, Coronal Hole-aware Diffusion Model Translator (CH-aware DMT), to reconstruct synthetic SDO/AIA 193 Å EUV images from \HeI{} inputs. The model is trained on temporally co-aligned SOLIS \HeI{} and AIA 193 Å pairs spanning 2011--2015 using a month-based split, where January--October are used for training, November is used for validation, and December for testing. On the held-out test set, the reconstructions preserve dominant full-disk EUV morphology (CC=0.92) and recover CH-related low-intensity structure (CC=0.84). We further assess historical applicability by (1) comparing reconstructed AIA 193 Å morphology with SOHO/EIT 195 Å over 2005--2015; (2) comparing reconstructed AIA 193 Å images generated from KPVT \HeI{} inputs against Yohkoh/SXT soft X-ray observations; and (3) evaluating long-term reconstructed disk-integrated emission statistics against observational EUV series and independent solar activity proxies (sunspot number and F10.7 radio flux over 1974--2015). These results indicate that CH-aware DMT conditioned on \HeI{} can provide a physically plausible synthetic AIA 193 Å coronal proxy for historical studies, supporting multi-decade analyses of large-scale coronal evolution before the direct EUV imaging was available.

Problem

• EUV image reconstruction
• He I 10830 Å
• solar corona
• historical solar observations
• coronal proxy

Innovation

• diffusion model
• image translation
• solar corona
• coronal holes
• EUV reconstruction