92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Thursday, 26 January 2012: 2:15 PM
Flow Characteristics in An Urban Area Located in Complex Terrain
Room 339 (New Orleans Convention Center )
Ann Dallman, Univ. of Notre Dame, Notre Dame, IN; and S. Di Sabatino, L. S. Leo, and H. J. S. Fernando

A field study was conducted in a mixed suburban/industrial neighborhood of South Phoenix, Arizona, where the local meteorology is mainly governed by thermal circulation induced by the surrounding complex terrain. The experiment was motivated by high pollutant concentrations in the area that has led to high incidences of respiratory problems. Low-flow velocities and near-stagnant transition periods confounded by fugitive dust and automobile emissions are believed to be the cause of poor air quality. Detailed measurements were taken to better characterize flow and turbulence and to identify salient flow processes so that findings can be used for similar environments and for validation of numerical models. Various instruments were used to estimate the atmospheric boundary layer height and to obtain vertical profiles of wind speed and direction, temperature and relative humidity. Turbulence measurements were also made from two towers, located approximately 1km apart, that included sonic anemometers mounted at three heights assumed to be in the urban canopy layer (UCL), roughness sublayer (RSL) and constant flux layer (CFL). The CFL, however, may or may not be present because of significant urban heat island effects in the nearby city center and constant changes in the wind direction. Several building morphometric parameters were measured to calculate aerodynamic roughness indicators of the neighborhood, and their dependence on wind direction was evaluated. The overall meteorological conditions dominated by up- and down-slope flows and their interactions with building morphology were assessed. The urban morphometry appears to have only a small effect on turbulence characteristics, possibly because the flow in the area is in the isolated roughness regime.

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