New Homogeneous Dataset of Solar EUV synoptic maps from SOHO/EIT and SDO/AIA

TL;DR

This paper introduces a new, standardized dataset of solar EUV synoptic maps from SOHO/EIT and SDO/AIA, enabling consistent long-term solar surface studies by homogenizing data across different instruments and years.

Contribution

The paper presents a novel homogenization method for combining EUV maps from different instruments, covering 1996-2018, with a large, systematic dataset for solar surface analysis.

Findings

Created 423 synoptic maps covering 1996-2018

Standardized intensity scales for EIT and AIA maps

Facilitates long-term solar surface studies

Abstract

Synoptic maps of solar EUV intensities have been constructed for many decades in order to display the distribution of the different EUV emissions across the solar surface, with each map representing one Carrington rotation (i.e., one rotation of the Sun). This paper presents a new solar EUV synoptic map dataset based on full-disk images from Solar and Heliospheric Observatory/Extreme Ultraviolet Imaging Telescope (SOHO/EIT) and Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA). In order to remove the significant and complicated drift of EIT and AIA EUV intensities due to sensor degradation, we construct the synoptic maps in standardized intensity scale. We describe a method of homogenizing the SOHO/EIT maps with SDO/AIA maps by transforming the EIT intensity histograms to AIA level. The new maps cover the years from 1996 to 2018 with 307 SOHO/EIT and 116 SDO/AIA synoptic maps, respectively. These maps provide a systematic and homogenous view of the entire solar surface in four EUV wavelengths, and are well suited, e.g., for studying long-term coronal hole evolution.