Barotropic and Baroclinic Processes Associated with Convective Development in the Deep Tropical Convective Regime

Barotropic and baroclinic processes associated with convective development in the deep tropical convective regime are examined through the analysis of budget of perturbation kinetic energy. The budget is calculated using the two-dimensional cloud-resolving model simulation during TOGA COARE. The major results include the followings: (1) The analysis of the budget shows that while baroclinic conversion from perturbation available potential energy to perturbation kinetic energy plays an important role in convective development, barotropic conversion from the mean kinetic energy to perturbation kinetic energy shows significant modification in the growth of perturbation circulations. The perturbation kinetic energy is also affected by vertical fluxes of perturbation water vapor and cloud hydrometeors. (2) Barotropic conversion is associated with vertical transport of zonal momentum acted on the vertical wind shear of the mean circulations. The further analysis of correlation reveals that vertical wind shear may determine the general evolution of barotropic conversion but the vertical transport of zonal momentum may be responsible for the significant change in barotropic conversion. The vertical wind shear does not have any significant impacts on variation of vertical transport of zonal momentum. (3) A prognostic equation of vertical transport of zonal momentum is constructed from the set of prognostic equations of perturbation zonal wind and vertical velocity in the two-dimensional cloud-resolving model framework. The tendency of vertical transport of zonal momentum is associated with dynamic processes, pressure-gradient-related processes and zonal transports of heat, water vapor and cloudhydrometeors. (4) Although the pressure gradient-related process and zonal flux of heat are the largest terms in the budget of vertical transport of zonal momentum, the analysis of the root-mean-squared difference and correlation shows that zonal flux of cloud hydrometeor may be responsible for the variation of vertical transport of zonal momentum.