J. Space Weather Space Clim.
Volume 12, 2022
|Number of page(s)||14|
|Published online||06 April 2022|
Detecting undocumented trends in solar irradiance observations
LPC2E, CNRS/CNES/University of Orléans, 45071 Orléans, France
* Corresponding author: firstname.lastname@example.org
Accepted: 14 October 2021
Quantifying the long-term stability of solar irradiance observations is crucial for determining how the Sun varies in time and detecting decadal climate change signals. The stability of irradiance observations is challenged by the degradation of instrumental sensitivity in space and by the post-launch corrections needed to mitigate this degradation. We propose a new framework for detecting instrumental trends based on the existing idea of comparing the solar irradiance at pairs of dates for which a proxy quantity reaches the same level. Using a parametric model, we then reconstruct the trend and its confidence interval at all times. While this method cannot formally prove the instrumental origin of the trends, the observation of similar trends with different proxies provides strong evidence for a non-solar origin. We illustrate the method with spectral irradiance observations from the Solar Radiation and Climate Experiment (SORCE) mission, using various solar proxies such as sunspot number, MgII index, F10.7 index. The results support the existence of non-solar trends that exceed the level of solar cycle variability. After correcting the spectral irradiance for these trends, we find the difference between the levels observed at solar maximum and at solar minimum to be in good agreement with irradiance models.
Key words: Solar irradiance / Solar proxies
© T. Dudok de Wit, Published by EDP Sciences 2022
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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