Problems to be solved
Recent statistical studies of observational records suggest that variation in solar activity play a significant part in natural climate variability but a physical mechanism to account for the apparent solar effects has not been fully developed. Through enhancement of solar UV, and increased ozone concentrations, it is possible that stratospheric processes may excite a response in the climate of the lower atmosphere.
Scientific objectives and approach
The objectives of the project are to assess the effects of solar variability on climate, including regional and seasonal effects. A coordinated programme of numerical modelling and data analysis will be conducted. The modelling studies will incorporate series of experiments with models of various types designed to investigate different aspects of the interaction of solar radiation with the chemical and dynamical structure of the lower and middle atmosphere. These will include the first ever simulations of the effect of variations in solar spectral irradiance, on both 27-day and 11-year time scales, on stratospheric ozone using general circulation models (GCMs) with coupled stratospheric chemistry. GCMs will also be used to study links between the stratosphere and tropospheric climate including the effects of solar-induced changes in stratospheric climate on wave propagation and how this is modulated by the quasi-biennial oscillation (QBO). The modulation of sea surface temperatures by solar variations and the effect on climate will be studied using a GCM with a coupled ocean in the context of other GCM climate simulations. Chemical transport models will allow detailed investigations of solar impact on stratospheric chemistry and 3D dynamical model of the middle atmosphere will be used to investigate the internal variability of the stratosphere, its response to solar variability and how this is impacted by the QBO. The data studies will involve the development of a unified method for the analysis of global three-dimensional fields of temperature and ozone in the context of the response of these fields to other factors including the QBO and volcanic eruptions. Comparison of the results of the modelling and data studies will be made to validate the models and the model results will then be analysed to elucidate details of the mechanisms whereby solar variability affects climate. The results will also be used to calculate solar radiative forcing parameters, taking proper account of the response of stratospheric ozone, and to estimate the regional impacts of solar variability. Expected impacts By providing new assessment of the solar radiative forcing of climate and assessment, of impacts of solar variability on seasonal and regional climate and on surface UV radiation important input to international detection/attribution studies can be expected. This, in turn, may impact on future environment and energy policies.
Funding SchemeCSC - Cost-sharing contracts
91371 Verrieres Le Buisson
OX11 0QX Didcot,harwell,chilton
10025 New York
RG12 2SZ Bracknell