Solar signal in atmospheric ozone, temperature and dynamics simulated with CCM SOCOL in transient mode

We have carried out a set of transient runs of the Chemistry-Climate Model SOCOL covering 1975-2000 driven by time evolving sea surface temperature and sea ice distributions, sulfate aerosol loading, spectral solar irradiance, greenhouse gases and ozone destroying substances. We present the solar signal in the atmosphere extracted from these transient runs. For the estimation of the atmospheric response to the solar irradiance variability we use multiple regression analysis to define the contribution of the imposed solar radiance changes to the time evolution of the simulated quantities and to estimate their sensitivity to the solar irradiance changes from the solar maximum to minimum cases. The solar signal extracted from the transient runs has been compared to the solar signal obtained from the steady-state simulations with the same model. In general, the ozone response obtained from the transient simulation is closer to the observation data analysis than the results obtained from the steady-state experiment. The ozone response in the lower mesosphere and upper stratosphere to the solar irradiance changes is mostly positive (≈ 1-2%). Above 30 km the ozone response is well pronounced (< 5%) and occurs at 40 km over the middle latitudes. The ozone response is smaller (< 2%) in the tropical middle stratosphere, while two additional maximums appear in the UTLS over the northern high and southern middle latitudes. The solar signal in the temperature extracted from the transient runs resembles the results of the steady-state run by the location and magnitude of the warming spots. The differences appear to be substantial only in the UTLS region over the middle latitudes. They comprise in the additional warming with magnitude exceeding 0.6 K. These elevated temperatures presumably reflect an intensification of the polar vortices. The solar signal obtained for several other simulated quantities is also analyzed.