Extended Abstract (1.7M)3.12
A comparative Study of dissipation Rates in urban and suburban Environments using sodar Data
Richard L. Coulter, ANL, Argonne, IL; and M. Pekour and T. J. Martin
Data from field studies in Oklahoma City, OK during July 2003 and Phoenix, AZ during June 2001 are used to calculate the structure function of velocity using the velocity differencing technique with sodar data. Appropriate corrections to the structure function for volume averaging and overlapping sample volumes are discussed. It is found that this technique can often be applied in these locations, particularly during summer, because of significant low frequency energy in the turbulence spectrum caused by strong solar forcing. However there are also significant periods when this technique is inappropriate, usually during nighttime, stable conditions. It is also found that during nighttime the method sometimes is useful at altitudes well above the surface even when conditions near the surface do not fit required criteria. This is likely because the source of turbulence during nighttime, particularly in Oklahoma City, is well above the surface, namely the nocturnal, low-level jet. Four different sites during each of the two experimental sites are used to compare velocity structure parameters, velocity structure functions, dissipation rates and vertical velocity variances within the urban heat island (including from the top of a building) and in suburban locations.
Session 3, results and opportunities associated with large collaborative intensive urban campaigns (e.g. Oklahoma Joint Urban Atmospheric Dispersion Study 2003) (parallel with sessions 2 and 4)
Monday, 23 August 2004, 10:30 AM-5:30 PM
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