Changes in the Structure of the Tropical Subcloud Layer from the Undisturbed to Disturbed States

Abstract

Results of the analysis of measurements of temperature, mixing ratio, and horizontal wind speed are presented. The data were collected using a tethered ballon system during the 1969 BOMEX during periods of undisturbed and disturbed weather conditions. The results show that substantial changes occur in the character and stratification of the lower subcloud layer from the undisturbed to disturbed states. The lapse rate, height of the mixed layer, and estimated surface fluxes under disturbed conditions are to be obtained from the observations. These values are applied to currently suggested parametric relationships of the mixed layer under undisturbed conditions. Totally unrealistic values of vertical motion are obtained. It is concluded that convective cloud scale downdrafts driven by evaporation are extremely important in determining the budget of the mixed layer under disturbed conditions.