Impacto de parametrizacoes de conveccao em ciclogenese sobre o oceano / The impact of convection parametrization on oceanic cyclogenesis

AUTOR(ES)
DATA DE PUBLICAÇÃO

1999

RESUMO

Numerical simulations of a South Atlantic cyclogenese event were performed in order to examine the role of three cumulus parameterizations (Kuo; Kain and Fritsch; Fritsch and Chappelly The atmospheric model employed is the Japan Meteorological Agency limited area model, adapted to the South America region. The effect of the cumulus parameterization depending on the horizontal resolution was examined by running the model with grid length of 75 km and 25 km. In a 72 h run with the 75 km grid-length two distinct phases were identified. The first phase, from 0 to 36 h, showed similar features for the three schemes. In the second phase, from 36 h onward, the Kuo parameterization yielded a more deeper cyclone. The similarities in the first phase were attributed to a wet and conditional unstable atmosphere surrounding the cyclone. Under these conditions, the total diabatic heating was very similar with the three schemes, although they presented different partitions between grid-scale and convective heating. In the second phase, the conditional instability arose on the north flank of the cyclone, where the Kain and Fritsch and Fritsch and Chappell schemes showed a larger areal convective activity than the Kuo. However, in the southern region of the cyclone the atmosphere became stable, and the grid-scale scheme was dominant in the three schemes. Nevertheless, the total diabatic heating was larger with the Kuo parameterization, which explains the more intense cyclone. The increase of the horizontal resolution enhanced the mesoscale structure associated with the cyclone. However no significant modifications on the two phases were observed. An additional experiment evidenced that the release latent heat played a crucial role on the development and displacement of the cyclone in both spatial resolutions.

ASSUNTO(S)

ciclones nuvens cumulus atlantico sul parametrizacao modelos atmosfericos estudo do tempo e do clima calor latente

ACESSO AO ARTIGO

Documentos Relacionados