CHARACTERISTICS OF THE TURBULENCE AND ATMOSPHERIC STABILITY AT BOGOTÁ

Abstract

For the first time for the Sabana of Bogotá, some characteristics of the turbulence and the atmospheric stability are analyzed according to the Monin Obuckov Theory. These characteristics are: The Friction velocity, the temperature scale, the Monin – Obuckov length and the sensible heat flux. Because this theory is not widely known, a derivation of these parameters, following the energetic method, is presented. Also, it is indicated how, these parameters may be included within a dispersion model.

The computation of these parameters was carried out with temperature measurements at 2m and 10m and wind measurements at 10m. Generally, the results show a high correlation within the diurnal heating and the increasing of the turbulence as follows:

Toward the noon and early afternoon increase; the friction velocity, the heat flux and the Monin – Obuckov length. The wind velocity also reaches the maximum value at this time too. Also it is noticeable a high correlation is seen between the diurnal increasing of the turbulence and the development of convection and formation of thunderstorms over this area. During the night, the wind become weak, the heat flux is negative and the Monin - Obuckov length positive leading to stable and neutral condition.

These results may be of interest in air pollution studies. Also, the link founded between the diurnal increasing of the surface turbulence and the convection activity, after a complementary and detailed confirmation of this finding, can be used as a predictive indicator of thunderstorm formation in regions where the upper air observation are absent.