Collaborative Research: The Diurnal Evolution of Stable Boundary Layers in an Enclosed Basin

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A three-year meteorological research program will be conducted to investigate the diurnal development of the nocturnal stable boundary layer (SBL) in the closed basin of Arizona's Meteor Crater. An extensive data set was collected there by the Principal Investigators (PIs) under NSF funding during October 2006. The experimental design in this small, circular, and comprehensively instrumented experimental basin has parallels to laboratory experiments. The field campaign provided a data set uniquely suited to support innovative analyses to answer extant scientific questions about SBL evolution within topography. The goal of the research is to determine the physical processes leading to SBL evolution in a closed basin, with the objectives of identifying the roles of drainage flows, turbulence, radiative transfer, and larger-scale ambient flows in SBL evolution. Novel and innovative concepts are featured with analyses and modeling informed by field experience and the PIs' initial analyses. The PIs will perform the first comprehensive investigation of SBL asymmetries during the transition periods when differential insolation occurs on the basin sidewalls. Hypotheses will be tested to determine the cause of unusual SBL thermal structure evolution in the crater. The topographic amplification factor concept will be tested for the first time with observational data. The relative roles of slope flows, radiative transfer and sensible heat flux in SBL development will be diagnosed. An analytical model of self-induced katabatic flow shutdown in basins will be developed. Exploratory investigations of turbulence characteristics will be made for the floor, sidewalls, and rim of a basin, as well as over the surrounding plain. Intellectual Merit: The research will advance knowledge and understanding of the physical processes that affect SBLs in complex terrain, and this knowledge is expected to lead to improvements in models and, ultimately, in weather forecasts for the western U.S. and throughout the world. The work explores innovative approaches and concepts and uses a combination of analyses and numerical modeling to gain understanding. Separately funded collaborators from other institutions and countries will contribute to the research. Broader Impacts: Potential benefits to society will accrue through improved understanding of SBL evolution with potential applications for air pollution dispersion, general and fire weather forecasting, and climate. Broader societal impacts are promoted through the infusion of the research into university teaching, the support of undergraduate and graduate students, the promotion of investigator/student diversity, and the development of training courses, workshops and seminars. Project results will be widely disseminated through peer-reviewed scientific publications, teaching modules, scientific presentations and web sites.