Olsson, Peter Q., author2022-02-242022-02-241994-11-28https://hdl.handle.net/10217/234408November 28, 1994.Also issued as author's dissertation (Ph.D.) -- Colorado State University, 1995.MCCs, a phenomenon occurring worldwide, by definition share certain structural and temporal features. Beyond the definition criteria, however, MCCs typically show a common organizational structure and evolution which cannot be directly attributed to the environment in which they evolve. This suggests that their evolution is governed by a set of physical laws which apply similarly to ensemble convective heating in a variety of mesoscale environments. In the middle latitudes, MCCs represent the extreme case of a large-amplitude energetic perturbation to the background environment. While substantial transients and observed, a separate class of non-radiating, balanced motions also evolve. These motions, and the altered thermal structure which balances them, are conveniently contained in a single quantity, the PV. The work described herein is an effort to understand the evolution of these balanced motions. To this end, a primitive equation (PE) numerical simulation of an MCC was performed. To isolate the balanced flow, a diagnostic system based on nonlinear balance is derived and discussed. This system is used to invert the PV and recover the rotational component of the balanced motion and the balanced mass field. A further application of the NLB approximation results in a diagnostic equation for the vertical velocity and, as well, a method for diagnosing the horizontal divergent motions which are "slaved" to it by the constraint of continuity. The PE simulation discussed herein agrees well with observations and produces many of the features frequently associated with MCCs including mesoscale convectively-induced vortices in the lower troposphere and a large anticyclone at upper levels. The nondivergent component of the PE model winds is found to consist, to a great degree, of balanced flow. More surprisingly, the storm-induced divergent model winds also remain reasonably balanced, though certainly less so than the nondivergent flow. The good agreement between model and balanced upward vertical mass flux suggests that the bulk of the three-dimensional unbalanced divergent motion may be attributed to gravity waves. The greatest disparity between the model and balanced circulations is found in the downward vertical motion, suggesting that the process of mass adjustment due to convective heating is largely dominated by unbalanced fast-manifold processes.reportsengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.Convection (Meteorology)Atmospheric circulationEvolution of balanced flow in a simulated mesoscale convective complexText