segunda-feira, 20 de maio de 2013

Seminário - Ciências Climáticas: O Clima no Holoceno

Holocene Climate in SPEEDY-MICON MODEL: Reconstruction data


David Mendes

22/05/2013 (quarta-feira) às 15h00 no Auditório do DFTE-CCET-UFRN  
Although the climate of the Holocene (11,500 cal yr B.P. to the present) has sustained the growth and development of modern society, there is surprisingly little systematic knowledge about climate variability during this period. Many paleoclimate studies over the last decade have highlighted the extreme climate fluctuations of the last glacial interval. If we are to understand the background of natural variability underlying anthropogenic climate change, however, it is important to concentrate on climate of the more recent past.
This work describes the formulation and climatology of an atmospheric general circulation model (GCM) of intermediate complexity, based on a spectral primitive-equation dynamical core and a set of simplified physical parametrization schemes. The parametrization package has been specially designed to work in models with just a few vertical levels, and is based on the same physical principles adopted in the schemes of stateof- the art GCMs. The parametrized processes include large-scale condensation, convection, clouds, short-wave and long-wave radiation, surface fluxes and vertical diffusion. In the current configuration, the model (nicknamed SPEEDY, from Simplified Parametrizations, primitivE-Equation DYnamics’’) has five vertical levels and a spectral truncation at total wave number 62 (T62L8).
Through simulation were made to the Holocene climate reconstructions in 39 atmospheric and oceanic variables.
To seek a more comprehensive view of natural climate variability during the present Holocene interglacial. We present in this paper a selection of globally distributed  climate proxy records. Examination of these records demonstrates that, although generally weaker in amplitude than the dramatic shifts of the last glacial cycle, Holocene climate variations have been larger and more frequent than is commonly recognized. Comparison of paleoclimate simulation with climate forcing suggests that changes in insolation related both to Earth’s orbital variations and to solar variability played a central role in the global scale changes in climate of the last 11,500 cal yr.
Influence occurs in climate?
1)     Climatic influence of the North Atlantic Ocillation (NAO) in the present climate and Holocene;
2)     Influence of Variability of the Equatorial Atlantic climate Tropical and sub​​-tropical;
3)     Dynamics of midlatitude;
4)     Arctic and Antarctic ice.
Through the multiparameter paleoclimate simulation assembled for this study, we make the case that Holocene climate has not been stable, but rather that it has been dynamic at scales significant to humans and ecosystems.  

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