Analysis of 20 years lidar measurements at middle latitude and 30 years rocket soundings from tropics to high latitude shows a clear response of the middle atmosphere temperature to the 11 years solar UV variation, with a positive or negative sign depending on the altitude and the latitude. This response cannot be interpreted as purely radiative because it should be positive everywhere. Simulations performed using a coupled chemistry-dynamics model of the middle atmosphere indicate that the threshold planetary wave amplitude to trigger a winter polar stratospheric warming is larger during solar maximum than during solar minimum due to a stronger temperature gradient from equator and pole. This nonlinear relation between solar UV irradiance and dynamics can explain the observed negative response of the stratospheric temperature at middle and high latitudes. In order to extend our studies to the relation between the solar forcing and the climate, we started the development of a new version of the IPSL global circulation model LMDz with an improved representation of the middle atmospheric chemistry and dynamics and better description of the solar UV irradiance.
35th COSPAR Scientific Assembly
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