scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...

STP12 Abstracts
Berlin, 12 - 16 July 2010
SCOSTEP Symposium 2010
Solar Influence on Climate: top down or bottom up?
Matthes Katja 1 , Garcia Rolando 2 , Meehl Gerald 2 , Arblaster Julie 3 , Sassi Fabrizio 4 , Van Loon Harry
5
1 Deutsches GeoForschungsZentrum Potsdam and Freie Universität Berlin, 2 National Centre for
Atmospheric Research, 3 Bureau of Meteorology, Melbourne, 4 Naval Research Laboratory,
Washington DC, 5 Colorado Research Associates, Boulder
To further investigate solar influence on climate via the recently proposed combined effects of the
stratospheric "top-down" and the tropospheric "bottom-up" mechanisms, we present a detailed analysis
of experiments carried out with NCAR's Whole Atmosphere Community Climate Model (WACCM3),
a chemistry-climate model that incorporates the whole atmosphere up to the lower thermosphere. The
simulations span 10 solar cycles with realistic time-varying solar forcing, a synthetic time-varying
QBO, and an interactive ocean. We analyze in detail the impact of UV variations on the stratosphere,
and their indirect circulation changes throughout the atmosphere, as well as changes in the tropical
troposphere, with special focus on changes in the tropospheric circulation patterns, cloud formation
and precipitation. The results will be compared to a similar WACCM experiment without a QBO to
highlight the role of the QBO in modulating the solar signal.