Modeling Decadal and Centennial Solar UV Irradiance Changes

TL;DR

This paper presents a 1000-year reconstruction of solar UV irradiance variations, combining empirical models and solar flux data to improve understanding of long-term solar influence on Earth's climate and atmospheric chemistry.

Contribution

It introduces an empirical framework that integrates cyclic and secular solar variability to reconstruct spectral UV irradiance over the past millennium.

Findings

Reconstructed solar UV irradiance shows significant centennial variability.

The model captures both 11-year cycle and long-term trends.

Results enhance understanding of solar influence on Earth's climate.

Abstract

Reconstructions of solar spectral irradiance - especially in the ultraviolet (UV) range - are crucial for understanding Earth's climate system. Although total solar irradiance (TSI) has been thoroughly investigated, the spectral composition of solar radiation offers a deeper insight into its interactions with the atmosphere, biosphere, and climate. UV radiation, in particular, plays a key role in stratospheric chemistry and the dynamics of stratospheric ozone. Reconstructing solar irradiance over the past centuries requires accounting for both the cyclic modulation of active-region coverage associated with the 11-year solar cycle and the longer-term secular trends, including their centennial variability. This study utilizes an empirical framework, based on a 1000-year record of Open Solar Flux, to characterize the various temporal components of solar irradiance variability. We then combine these components to reconstruct Solar UV irradiance variations in spectral bands crucial for Earth's atmospheric studies.