| The present study develops and uses a cumulus parameterization that will not merely produce a correct forecast, but will do so by simulating the same processes that directly control convection in the real atmosphere. This enables the parameterization to be used to produce numerical simulations that will reveal the behavior and influence of convection in the real atmosphere under a broad range of conditions.; A diagnostic study examines the relative importance of the various physical processes that combine to produce the heating, drying, and precipitation in the one-dimensional cloud model that is used in the cumulus parameterization. Processes, such as lateral detrainment, that affect the net vertical mass flux of modeled clouds are shown to be most important to consider in devloping the cumulus parameterization.; The cumulus parameterization is used in a mesoscale numerical model to simulate tropical mesoscale convective systems. The structures and life cycles of the simulated systems are quite similar to those observed in many studies of tropical convection, supporting the use of the parameterization in mesoscale models. The modeled cloud lines form extensive upper level nimbostratus clouds, primarily from air detrained below cloud top by the parameterized convection.; In a series of experiments with the mesoscale model, different types of large-scale forcing are held constant and the response of the model atmosphere is examined. The influences of moisture convergence, adiabatic cooling, low level upward motion, synoptic scale easterly waves, and radiation on rainfall and the resulting vertical thermodynamic structure are investigated. The amount of rainfall produced in the model is most sensitive to processes that destabilize the atmosphere. Different types of large scale forcing consistently produce similar vertical profiles of changes in temperature and water vapor mixing ratio, and the soundings move closer to a moist virtual adiabat. |
