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Will Pendergrass NOAA/ARL/ATDD OAR Senior Research Council Meeting Oak Ridge, TN

Boundary–Layer Dispersion Urban Meteorology. Will Pendergrass NOAA/ARL/ATDD OAR Senior Research Council Meeting Oak Ridge, TN August 18-19, 2010. The DCNet Urban Testbed. 2000. 100. I. D. L. H. =. 3. 0. m. g. /. m. *. *. 3. 1600. 10. P. E. L. =. 3. m. g. /. m. *.

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Will Pendergrass NOAA/ARL/ATDD OAR Senior Research Council Meeting Oak Ridge, TN

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  1. Boundary–Layer Dispersion Urban Meteorology Will Pendergrass NOAA/ARL/ATDD OAR Senior Research Council Meeting Oak Ridge, TN August 18-19, 2010 Air Resources Laboratory

  2. The DCNet Urban Testbed Air Resources Laboratory

  3. 2000 100 I D L H = 3 0 m g / m * * 3 1600 10 P E L = 3 m g / m * * 3 1 3 * * m 0.1 / 1200 g m 0.01 0.001 800 0.0001 400 0 0 2000 4000 6000 Why Urban Micrometeorology? • The lowest layers of the Atmosphere are in direct contact with where people work, play, live. Hence, we need to understand atmospheric flow behavior over various terrain, especially over populated regions! • Dispersion forecast models mainly rely on parameterizations and relations derived from research over “ideal” (i.e., rural, flat, homogeneous) terrain. We need to generate improved parameterizations to help models perform better over complex urban areas! • Improving parameterizations means collecting measurements! 5 degrees 15 degrees 25 degrees Air Resources Laboratory

  4. DCNet DCNet is a NOAA dispersion forecasting program, intended to (a) to determine how best to make use of local data in order to derive an acceptably accurate product and (b) to provide DC with the best possible dispersion forecasting system. Air Resources Laboratory

  5. Current • DCNet Stations 2 km 5 km Air Resources Laboratory

  6. Urban Complications Air Resources Laboratory

  7. Do Urban Observations Make a Difference? DCNet Enhanced NAM12 plume and trajectory HYSPLIT4 Simulations DCNet Non-Enhanced NAM12 plume and trajectory Air Resources Laboratory

  8. Urban Climatology Air Resources Laboratory

  9. Urban Heat Island Q = K ↓- K ↑ +L ↓ - L ↑ = QH + QE + ∆QS Sensible Heat Flux Air Resources Laboratory

  10. Urban Velocity Profiles Modeled Observed Profiles Air Resources Laboratory

  11. Apparent Flow Regime Air Resources Laboratory

  12. 2010 CalNexus Science Questions • Transport and Meteorology • Goal: Improved Urban • Canopy Layer • Parameterizations • How best can we characterize and model air flow over coastal waters and the complex terrain of California? • What are the major deficiencies in the representation of chemistry and meteorology in research and operational models and how can models be improved through the collection of additional measurements? What physical and chemical processes are not captured well by available models? Is there an optimum grid resolution to capture all of the relevant physical and chemical processes that occur? Air Resources Laboratory

  13. Study Focus Urban Canopy Model Urban State Variables "URBAN ROOF SKIN TEMPERATURE" "K" "URBAN WALL SKIN TEMPERATURE" "K" "URBAN ROAD SKIN TEMPERATURE" "K" "URBAN CANOPY TEMPERATURE" "K" "URBAN CANOPY WIND SPEED" "K" "URBAN CANOPY HUMIDITY" "kg kg{-1}" "M-O LENGTH ABOVE URBAN ROOF" "dimensionless" "M-O LENGTH ABOVE URBAN WALL" "dimensionless" "M-O LENGTH ABOVE URBAN ROAD" "dimensionless" "M-O LENGTH ABOVE URBAN CANOPY" "dimensionless" "ROOF LAYER TEMPERATURE" "K" "WALL LAYER TEMPERATURE" "K" "ROAD LAYER TEMPERATURE" "K" "SENSIBLE HEAT FLUX FROM URBAN SFC" "W m{-2}" "LATENT HEAT FLUX FROM URBAN SFC" "W m{-2}" "GROUND HEAT FLUX INTO URBAN" "W m{-2}" "NET RADIATION ON URBAN SFC" "W m{-2}" "COS of SOLAR ZENITH ANGLE" "dimensionless" "SOLAR HOUR ANGLE" "dimensionless" "SOLAR DECLINATION" "dimensionless" Air Resources Laboratory

  14. CalNex: Pasadena Calnex Pasadena Monitoring Station Keck Laboratories Air Resources Laboratory

  15. Estimating sensible heat flux from surface temperatures Air Resources Laboratory

  16. Urban friction coefficient: Cf Skimming Flow DCNet: Federal Triangle CalNex: Pasadena Air Resources Laboratory

  17. CalNex Status • Meteorological data transferred to community ftp site • Abstract submitted for AGU special session • High frequency spectral data in review • Complete energy balance components in review Air Resources Laboratory

  18. Urban Meteorology Future Directions • Conduct research over other types of terrain such as suburban regions, coastal cities, etc… • Assess changes in turbulent flow along transects from suburban to urban to suburban. • Assess spatial variability of vertical profiles of mean winds and turbulence; mobile remote sensing. • Observe the budget of TKE: Does the oft-used “local dissipation” assumption for turbulence (rates of mechanical and buoyant production equals rate of viscous dissipation) hold above the urban canopy? Air Resources Laboratory

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