Explicit simulation of cumulus ensembles with the GATE phase III data: Budgets of a composite easterly wave

The mass, heat and moisture budgets of a composite easterly wave over the e astern tropical Atlantic are analysed from simulations of a convection-reso lving model (CRM). The large-scale data from the GARP (Global Atmospheric R esearch Program) Atlantic Tropical Experiment (GATE) phase III are used to drive the CRM simulations. The simulated, composite easterly wave is reason ably comparable with the observed, except for the lack of shallow convectio n embedded in the simulated easterly waves. The mesoscale stratiform precip itation processes are found to be an inseparable component of cumulus conve ction embedded in the easterly waves. Their main differences from convectiv e processes are twofold: (1) the distinct vertical structures of the budget components due to mesoscale updraughts and downdraughts, and (2) the phase lags relative to the convective processes in the temporal evolution of the easterly waves. Thus, theoretical studies should include both convective a nd mesoscale stratiform precipitation processes in order to further underst anding of diabatic processes in the dynamics of the easterly waves and poss ibly other waves in the tropics. In addition, the budget analysis presented in this study also provides some details for improving parametrizations of cumulus convection.