Simulação numérica de circulações de brisa no Estado da Paraíba.

Abstract

The Regional Atmospheric Modeling System (RAMS) installed at the Laboratorio de Modeiagem e Desenvolvimento (LMD) of the Departamento de Ciencias Atmosfericas - Universidade Federal da Paraiba is used to simulate breeze-like circulations in Paraiba state, Northeast Brazil. Four two-dimensional model simulations allow to evaluate the importance of topography, convection and their nonlinear interation for breezes' formation and development by means of differences between experiments; (i) with topography and convection; (ii) with topography, without convection; (iii) without topography, with convection, and (iv) without topography and convection. The 48 hour-long simulations are initialized from a homogeneous atmosphere at rest, based on a thermodynamic vertical profile obtained in Campina Grande (7°13'S, 35°53'W, 547m), located in Paraiba. The model is run in non-hydrostatic mode, with a 60-point 22 km horizontal grid resolution and variable vertical grid spacing. Chen's radiation and Kuo's convection parameterizations are used. Results show; (i) The sea breeze attains its maximum strength of 2.5 ms"1 between 17 and 18 LT, in accordance with observations; its westernmost position is reached around 24 LT; (ii) The convection can favour or not sea breeze formation, and development; (iii) The topography determines preferred regions for location of convergence/divergence; it induces stronger heating at low levels above the land surface and a deepening of the mixing layer, favouring sea breeze formation; (iv) The nonlinear interaction between topography and convection preserves main characteristics of both effects, such as the longitudinal organization of the convergence/divergence areas and upper level divergence.