Inclusion of the momentum perturbation in the kain-fritsch cumulus parameterization scheme and impacts on a convective rain case / Inclusão da perturbação de momentum no esquema de parametrização de cumulus kain-fritsch e impactos sobre um caso de chuva convectiva

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The objective of this work is to insert the vertical transport of momentum through the mass flux in the Kain-Fritsch convective parameterization scheme. The momentum fluxes were inserted in the KF scheme in a similar way to the existing heat fluxes. Experiments were accomplished in the two domains, one experiment with cloud updraft (FM1) and one experiment including the cloud updraft and downdraft (FM2). In this work two domains were used. The domain 1, 2000 x 2000 km, was centered at 24.5 oS and 51.0 oW, with 15 km horizontal resolution and 38 levels, Eta15L38. The domain 2, 200 x 200 km was positioned inside of the domain 1 and centered at Foz do Iguaçu (25.6 oS / 54.6 oW), with 5 km horizontal resolution and 60 levels, Eta05L60. A case study was carried out for a cold front case. The control experiment, without momentum (NoFM) transport, and the experiments FM1 and FM2 were accomplished for 48 h of simulation. The adjustments of the new scheme were presented for a cloud column. The new scheme accelerates, in general, the winds in altitude and near to the surface and it reduces the intensity of the maximum winds. The effects of the experiments FM1 and FM2 could be identified in the areas of convective activities generated in the simulations, which increased of the humidity convergence in 850 hPa and mass divergence in 300 hPa. These conditions were associated with the intensification of the cyclonic vorticity in 850 hPa and production of anticiclonic vorticity in 300 hPa. The values of the thermodynamic and dynamic instabilities indexes calculated after 24 h of simulations, in general, they were endorsed by the observations of the Foz do Iguaçu sounding, which showed an improvement with the modifications in the KF scheme.

ASSUNTO(S)

previsão numérica do tempo momentum transfer parametrization cumulus clouds updraft convectivas corrente ascendente convection currents momentum flux parametrização de cumulus fluxo de momentum numerical weather forecasting meteorologia correntes transporte vertical de momentum meteorology

ACESSO AO ARTIGO

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