x / Experimentos numericos com modelos climaticos media zonal

AUTOR(ES)
DATA DE PUBLICAÇÃO

1989

RESUMO

Two statistical-dynamical models, a quasi-geostrophic and a primitive equations model are developed. These are used to conduct numerical experiments about the zonally-averaged atmosphere, with emphasis on the Southern Hemisphere climatic processes. The experiments consider the climatic effects caused by the sea-surface temperature (SST) anomalies and by land surface alterations. The experiments regarding the SST anomalies consider the situations of "El Nino", "La Nina" and the dipole involving centers of positive and negative anomalies. The results show that in the "El Nino" situation the sub-tropical jet stream and the Hadley circulation are intensified and the surface temperature increases in the perturbed region. The opposite situation occurs in the case of "La Nina". In the dipole experiment there is an intensification of the Hadley cell. in the Northern Hemisphere (region of positive anomalies) and a weakening in the ascending branch in the Southern Hemisphere (region of negative anomalies). In the experiment of the surface state modification the interaction between the geobotanic state and the climate is considered. The interaction constitutes a bio-feedback mechanism. Experiments are done about the deforestation, desertification and irrigation situations. The results show that the change in the evapotranspiration rather than the change in the surface albedo is the predominant effect in regulating the changes in the surface temperature. A notable aspect in these bio-feedback experiments is that all the variations (experiment with perturbation minus control) are smaller in the Southern Hemisphere. This fact may be explained by the smaller land fraction that exists in the Southern Hemisphere.

ASSUNTO(S)

hemisferio sul el nino la nina ciencias meteorologicas climatologia dinamica

ACESSO AO ARTIGO

Documentos Relacionados