| Deep convective systems over many parts of the globe organize into similar complexes with a common evolution. The purpose of this study is to gain insight into basic fundamental processes responsible for convection organizing into large clusters such as Mesoscale Convective Complexes (MCCs) and to find a dynamically meaningful distinction between MCC-like clusters and other deep convection. These matters are investigated through idealized numerical experiments using a cloud-resolving, nonhydrostatic model. Modeling issues involving convective initiation and heterogeneous nonuniformly sheared base states with Coriolis effect are addressed.; The hypothesis of organization and growth by mesoscale shear instability was studied with dry experiments and explicit cloud microphysics in a linearly unstable vertical shear profile. The shear instability was not manifested. Instead, the dry box experiments gave Rayleigh rolls and the moist experiment resulted in a heavy-raining convective system organized by short gravity waves, the cold dome, and a mesoscale crossover downdraft. The mesoscale downdraft occurred beneath patches of negative potential vorticity (PV), suggesting importance of the PV signature in mesoscale organization.; The PV signature and mesoscale circulations as a response to thermal forcing were studied in more detail through dry, initially barotropic experiments with specified, spatially fixed heating distributions and with heating proportional to vertical motion. Particular attention was given to warm core vortex structures resembling those other investigators found associated with MCCs and serving as seeds for tropical cyclones.; Warm core vortices were produced in many of the experiments through a variety of mechanisms. Some interesting scenarios producing mesoscale vortices were a layer of cooling resembling melting from an MCC anvil, a line of deep heating, and favorably arranged cloud-scale heating centers. Heating inside a pre-existing warm core vortex favored intensification due to radial (horizontal) vorticity contributions to PV generation.; The experiments provide an interesting basis for discussing balance or lack of it and the adjustment process for mesoscale disturbances. Thin, slow internal waves can reduce the Rossby radius to the vortex scale.; This research suggests that production or organization around a rotationally balanced mesovortex is the dynamically distinguishing factor of MCC-like systems. |
