Invited Presentation: Evaluation of urban-dynamic and aerosol impacts on summer thunderstorms

Urban areas impact summer thunderstorms through direct and indirect dynamic, thermodynamic, and cloud microphysical processes, which result in either initiation of new storms or splitting of existing moving storms. As these processes can increase or decrease precipitation amounts over and around urban areas, as well as impact its timing, location, and intensity, no clear understanding has emerged on a grand synthesis. It is thus proposed to establish of one or more modeling case studies to evaluate the relative roles of urban dynamics and aerosols on summer thunderstorms. The presentation reviews the literature on the relative roles of urban dynamics and aerosols on summer thunderstorms, and then proposes a process whereby case studies could be selected for simulation by interested meso-met modelers. The process would include establishment of: (a) a coordinating committee to oversee the exercise, (b) criteria for the submission of interesting case studies (i.e., documentation of a clearly urban-impacted case; and description of available surface and PBL data sets), (c) a list of model-meta- and input-parameters to be supplied, (d) a list of output-fields and graphics to be submitted, and (e) procedures to present the combined results from the exercise as reports, conference, papers, and journal papers.