University of Cambridge > Talks.cam > Centre for Atmospheric Science seminars, Chemistry Dept. > Our current understanding of solar irradiance and its effect on stratospheric ozone

Our current understanding of solar irradiance and its effect on stratospheric ozone

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If you have a question about this talk, please contact Dr Amanda Maycock.

Absorption of solar ultraviolet (UV) radiation by ozone is the main source of heating in the stratosphere, affecting the chemistry, temperature and dynamics of the atmosphere. Knowing (i) by how much the Sun varies spectrally on decadal and longer timescales and (ii) how it interacts with the Earth are key to understanding its influence on our climate.

Here, I will review the present state of the art in observations and models of solar irradiance. I will focus on comparing the SATIRE -S model with the NRLSSI model and SORCE observations. Together, these datasets encompass the full range of observed and modelled spectral solar irradiance (SSI) SC changes. SATIRE -S and NRLSSI show similar SC changes below 250 nm. However, SATIRE -S show almost double the change in flux as NRLSSI between 250 and 310 nm, but less than half that of SORCE /SOLSTICE. These various UV changes lead to different ozone responses in the stratosphere.

I will provide a test to show how the different SC SSI changes affect equatorial stratospheric ozone. Instead of just comparing the modelled ozone response to these different SSI datasets with ozone observations, I pose the question: can the observed SC change in stratospheric ozone constrain the allowed range of solar UV changes? I will show how this can be done using a simple linear approximation combined with a Bayesian formalism. The approach presented here could be extended to provide a better understanding of both variations in SSI and the atmospheric response to it.

This talk is part of the Centre for Atmospheric Science seminars, Chemistry Dept. series.

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