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Importance of diabatic processes on ageostrophic circulations observed during the F RONTS 87 experiment
Author(s) -
Lagouvardos K.,
Lemaitre Y.,
Scialom G.
Publication year - 1993
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49711951405
Subject(s) - diabatic , parametrization (atmospheric modeling) , convection , adiabatic process , latent heat , condensation , front (military) , circulation (fluid dynamics) , geology , evaporation , cold front , secondary circulation , climatology , meteorology , atmospheric sciences , mechanics , physics , thermodynamics , quantum mechanics , radiative transfer
The impact of condensation and evaporation on real cross‐frontal circulations is studied, using data from the F RONTS 87 field experiment. The Sawyer‐Eliassen equation is solved numerically in its primitive equation form, for one intensive observing period of F RONTS 87. Three different schemes of parametrization of condensation heating are used. Comparison between diagnosed and observed ageostrophic circulations shows that latent heat release plays an important role in enhancing the ascending branch of the ageostrophic circulation ahead of the frontal zone. In particular, when a parametrization scheme for the low‐level moisture convergence is applied, a cell of strong ascending motion is formed ahead of the frontal zone, in good agreement with the observations. Further, a simple parametrization of evaporative cooling below the frontal discontinuity leads to a reinforcement of downdraughts in the cold sector of the front, as observed in regions where precipitation originating from the strong line convection evaporates. In comparison with their adiabatic counterparts, the current solutions show strong similarities with the observed circulation and indicate the predominance of diabatic effects in the frontal zone.