• Arnfield, A. J., 2003: Two decades of urban climate research: A review of turbulence, exchanges of energy and water, and the urban heat island. Int. J. Climatol., 23, 126.

    • Search Google Scholar
    • Export Citation
  • Barlow, J. F., and S. E. Belcher, 2002: A wind tunnel model for quantifying fluxes in the urban boundary layer. Bound.-Layer Meteor., 104, 131150.

    • Search Google Scholar
    • Export Citation
  • Chen, B. Z., T. A. Black, N. C. Coops, T. Hilker, J. A. Trofymow, and K. Morgenstern, 2009: Assessing tower flux footprint climatology and scaling between remotely sensed and eddy covariance measurements. Bound.-Layer Meteor., 130, 137167.

    • Search Google Scholar
    • Export Citation
  • Christen, A., 2005: Atmospheric turbulence and surface energy exchange in urban environments—Results from the Basel Urban Boundary Layer Experiment (BUBBLE). Rep. Stratus 11 (Ph.D. dissertation, University of Basel, Switzerland), 140 pp. [Available online at http://edoc.unibas.ch/228/1/DissB_7159.pdf.]

    • Search Google Scholar
    • Export Citation
  • Christen, A., and R. Vogt, 2004: Energy and radiation balance of a central European city. Int. J. Climatol., 24, 13951422.

  • Christen, A., R. Vogt, and M. W. Rotach, 2009: The budget of turbulent kinetic energy in the urban roughness sublayer. Bound.-Layer Meteor., 131, 193223.

    • Search Google Scholar
    • Export Citation
  • Coceal, O., T. G. Thomas, I. P. Castro, and S. S. Belcher, 2006: Mean flow and turbulence statistics over groups of urban-like cubical obstacles. Bound.-Layer Meteor., 121, 491519.

    • Search Google Scholar
    • Export Citation
  • De Bruin, H. A. R., W. M. L. Meijninger, A. S. Smedman, and M. Magnusson, 2002: Displaced-beam small aperture scintillometer test. Part 1: The Wintex data set. Bound.-Layer Meteor., 105, 129148.

    • Search Google Scholar
    • Export Citation
  • Eliasson, I., B. Offerle, C. S. B. Grimmond, and S. Lindqvist, 2006: Wind fields and turbulence statistics in an urban street canyon. Atmos. Environ., 40, 116.

    • Search Google Scholar
    • Export Citation
  • Feigenwinter, C., R. Vogt, and E. Parlow, 1999: Vertical structure of selected turbulence characteristics above an urban canopy. Theor. Appl. Climatol., 62, 5163.

    • Search Google Scholar
    • Export Citation
  • Grimmond, C. S. B., J. A. Salmond, T. R. Oke, B. Offerle, and A. Lemonsu, 2004: Flux and turbulence measurements at a densely built-up site in Marseille: Heat, mass (water and carbon dioxide), and momentum. J. Geophys. Res., 109, D24101, doi:10.1029/2004JD004936.

    • Search Google Scholar
    • Export Citation
  • Harman, I. N., and S. E. Belcher, 2006: The surface energy balance and boundary layer over urban street canyons. Quart. J. Roy. Meteor. Soc., 132, 27492768.

    • Search Google Scholar
    • Export Citation
  • Kanda, M., R. Moriwaki, M. Roth, and T. R. Oke, 2002: Area-averaged sensible heat flux and a new method to determine zero-plane displacement length over an urban surface using scintillometery. Bound.-Layer Meteor., 105, 177193.

    • Search Google Scholar
    • Export Citation
  • Kanda, M., A. Inagaki, M. O. Letzel, S. Raasch, and T. Watanabe, 2004: LES study of the energy imbalance problem with eddy covariance fluxes. Bound.-Layer Meteor., 110, 381404.

    • Search Google Scholar
    • Export Citation
  • Kanda, M., R. Moriwaki, and F. Kasamatsu, 2006: Spatial variability of both turbulent fluxes and temperature profiles in an urban roughness layer. Bound.-Layer Meteor., 121, 339350.

    • Search Google Scholar
    • Export Citation
  • Kaufmann, P., and O. Weber, 1996: Classification of mesoscale wind fields in the MISTRAL field experiment. J. Appl. Meteor., 35, 19631979.

    • Search Google Scholar
    • Export Citation
  • Kleissl, J., C. J. Watts, J. C. Rodríguez, S. Naif, and E. R. Vivoni, 2009: Scintillometer Intercomparison Study—Continued. Bound.-Layer Meteor., 130, 437443.

    • Search Google Scholar
    • Export Citation
  • Kormann, R., and F. X. Meixner, 2001: An analytical footprint model for non-neutral stratification. Bound.-Layer Meteor., 99, 207224.

    • Search Google Scholar
    • Export Citation
  • Loescher, H., and Coauthors, 2005: Comparison of temperature and wind statistics in contrasting environments among different sonic anemometer–thermometers. Agric. For. Meteor., 133, 119139.

    • Search Google Scholar
    • Export Citation
  • Louka, P., S. E. Belcher, and R. G. Harrison, 2000: Coupling between air flow in streets and the well-developed boundary layer aloft. Atmos. Environ., 34, 26132621.

    • Search Google Scholar
    • Export Citation
  • Martilli, A., 2002: Numerical study of urban impact on boundary layer structure: Sensitivity to wind speed, urban morphology, and rural soil moisture. J. Appl. Meteor., 41, 12471266.

    • Search Google Scholar
    • Export Citation
  • Masson, V., 2000: A physically-based scheme for the urban energy budget in atmospheric models. Bound.-Layer Meteor., 94, 357397.

  • Masson, V., 2006: Urban surface modeling and the meso-scale impact of cities. Theor. Appl. Climatol., 84, 3545.

  • Masson, V., C. S. B. Grimmond, and T. R. Oke, 2002: Evaluation of the Town Energy Balance (TEB) scheme with direct measurements from dry districts in two cities. J. Appl. Meteor., 41, 10111026.

    • Search Google Scholar
    • Export Citation
  • Mauder, M., C. Liebethal, M. Göckede, J.-P. Leps, F. Beyrich, and T. Foken, 2006: Processing and quality control of flux data during LITFASS-2003. Bound.-Layer Meteor., 121, 6788.

    • Search Google Scholar
    • Export Citation
  • Nadeau, D. F., and Coauthors, 2009: Estimation of urban sensible heat flux using a dense wireless network of observations. Environ. Fluid Mech., 9, 635653.

    • Search Google Scholar
    • Export Citation
  • Nunez, M., and T. R. Oke, 1977: The energy balance of an urban canyon. J. Appl. Meteor., 16, 1119.

  • Offerle, B., C. S. B. Grimmond, K. Fortuniak, and W. Pawlak, 2006: Intra-urban differences of surface energy fluxes in a central European city. J. Appl. Meteor. Climatol., 45, 125136.

    • Search Google Scholar
    • Export Citation
  • Offerle, B., I. Eliasson, C. S. B. Grimmond, and B. Holmer, 2007: Surface heating in relation to air temperature, wind and turbulence in an urban street canyon. Bound.-Layer Meteor., 122, 273292.

    • Search Google Scholar
    • Export Citation
  • Poggi, D., and G. C. Katul, 2008: The effect of canopy roughness density on the constitutive components of the dispersive stresses. Exp. Fluids, 45, 111121.

    • Search Google Scholar
    • Export Citation
  • Raupach, M. R., and R. H. Shaw, 1982: Averaging procedures for flow within vegetation canopies. Bound.-Layer Meteor., 22, 7990.

  • Rotach, M. W., 1991: Turbulence within and above an urban canopy. Dissertation 9439, ETH, Zurich, Switzerland, 240 pp.

  • Rotach, M. W., 1993: Turbulence close to a rough urban surface. Part II: Variances and gradients. Bound.-Layer Meteor., 66, 7592.

  • Rotach, M. W., 1995: Profiles of turbulence statistics in and above an urban street canyon. Atmos. Environ., 29, 14731486.

  • Rotach, M. W., and Coauthors, 2005: BUBBLE—An urban boundary layer meteorology project. Theor. Appl. Climatol., 81, 231261.

  • Roth, M., 1991: Turbulent transfer characteristics over a suburban surface. Ph.D. thesis, The University of British Columbia, Vancouver, BC, Canada, 292 pp.

    • Search Google Scholar
    • Export Citation
  • Roth, M., 1993: Turbulent transfer relationships over an urban surface. II: Integral statistics. Quart. J. Roy. Meteor. Soc., 119, 11051120.

    • Search Google Scholar
    • Export Citation
  • Roth, M., 2000: Review of atmospheric turbulence over cities. Quart. J. Roy. Meteor. Soc., 126, 941990.

  • Roth, M., and T. R. Oke, 1993: Turbulent transfer relationships over an urban surface. I: Spectral characteristics. Quart. J. Roy. Meteor. Soc., 119, 10711104.

    • Search Google Scholar
    • Export Citation
  • Roth, M., and T. R. Oke, 1995: Relative efficiencies of turbulent transfer of heat, mass, and momentum over a patchy urban surface. J. Atmos. Sci., 52, 18631874.

    • Search Google Scholar
    • Export Citation
  • Roth, M., J. A. Salmond, and A. N. Satyanarayana, 2006: Methodological considerations regarding the measurement of turbulent fluxes in the urban roughness sublayer: The role of scintillometery. Bound.-Layer Meteor., 121, 351375.

    • Search Google Scholar
    • Export Citation
  • Salmond, J. A., T. R. Oke, C. S. B. Grimmond, S. Roberts, and B. Offerle, 2005: Venting of heat and carbon dioxide from urban canyons at night. J. Appl. Meteor., 44, 11801194.

    • Search Google Scholar
    • Export Citation
  • Schmid, H. P., H. A. Cleugh, C. S. B. Grimmond, and T. R. Oke, 1991: Spatial variability of energy fluxes in suburban terrain. Bound.-Layer Meteor., 54, 249276.

    • Search Google Scholar
    • Export Citation
  • Schotanus, P., F. T. N. Nieuwstadt, and H. A. R. de Bruin, 1983: Temperature measurement with a sonic anemometer and its application to heat and moisture fluxes. Bound.-Layer Meteor., 26, 8193.

    • Search Google Scholar
    • Export Citation
  • Stewart, I. D., 2011: Advancing the study of urban heat islands through research synthesis and local climate classification. Ph.D. thesis, The University of British Columbia, Vancouver, BC, Canada, 351 pp.

    • Search Google Scholar
    • Export Citation
  • Thiermann, V., and H. Grassl, 1992: The measurement of turbulent surface-layer fluxes by use of bichromatic scintillation. Bound.-Layer Meteor., 58, 367389.

    • Search Google Scholar
    • Export Citation
  • Webb, E., G. Pearman, and R. Leuning, 1980: Correction of flux measurement for density effects due to heat and water vapour transfer. Quart. J. Roy. Meteor. Soc., 106, 85100.

    • Search Google Scholar
    • Export Citation
  • Yoshida, A., K. Tominaga, and S. Watatani, 1991: Field measurements on energy balance of an urban canyon in the summer season. Energy Build., 15, 417423.

    • Search Google Scholar
    • Export Citation
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Can Surface-Cover Tiles Be Summed to Give Neighborhood Fluxes in Cities?

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  • 1 University of Auckland, Auckland, New Zealand
  • | 2 National University of Singapore, Singapore
  • | 3 University of British Columbia, Vancouver, British Columbia, Canada
  • | 4 University of Western Ontario, London, Ontario, Canada
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Abstract

The paper addresses the question of whether the modeling practice of summing separate land-cover tiles to give urban fluxes at the neighborhood scale has merit. A central-city site in Basel, Switzerland, was instrumented to measure turbulent sensible heat fluxes QH from the two main land-cover types (roofs and canyons) separately and from the whole neighborhood. Path-averaged QH values were measured in the roughness sublayer (RSL) using scintillometry, and the spatially averaged QH neighborhood-scale flux was measured in the inertial sublayer (ISL) by an eddy-covariance system. The roof and canyon flux results are combined and weighted according to the respective plan-area abundance of each to give an estimated value of the neighborhood flux. The results show that this “bottom up” approach underestimates the measured ISL values by about 25% when averaged across all periods and wind directions. This finding led to consideration of possible errors from instrumentation, inappropriate turbulent source areas, failure to sample representative surfaces, and inability to fully capture RSL heat exchange. Sorting data by the two main wind directions revealed significant differences. The measured fluxes in the ISL and across the canyon top depend little upon wind direction, but daytime roof values show a marked sensitivity to wind direction. Qualitative analysis suggests this might be caused by systematic controls such as solar angle, site morphometry, and observational setup. The comparison of bottom up versus ISL is inconclusive; in some conditions agreement appears promising, and in others it does not. The question has not been proven or disproven. It may be too ambitious to test the concept at a real-world site.

Corresponding author address: J. A. Salmond, School of Environment, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. E-mail: j.salmond@auckland.ac.nz

Abstract

The paper addresses the question of whether the modeling practice of summing separate land-cover tiles to give urban fluxes at the neighborhood scale has merit. A central-city site in Basel, Switzerland, was instrumented to measure turbulent sensible heat fluxes QH from the two main land-cover types (roofs and canyons) separately and from the whole neighborhood. Path-averaged QH values were measured in the roughness sublayer (RSL) using scintillometry, and the spatially averaged QH neighborhood-scale flux was measured in the inertial sublayer (ISL) by an eddy-covariance system. The roof and canyon flux results are combined and weighted according to the respective plan-area abundance of each to give an estimated value of the neighborhood flux. The results show that this “bottom up” approach underestimates the measured ISL values by about 25% when averaged across all periods and wind directions. This finding led to consideration of possible errors from instrumentation, inappropriate turbulent source areas, failure to sample representative surfaces, and inability to fully capture RSL heat exchange. Sorting data by the two main wind directions revealed significant differences. The measured fluxes in the ISL and across the canyon top depend little upon wind direction, but daytime roof values show a marked sensitivity to wind direction. Qualitative analysis suggests this might be caused by systematic controls such as solar angle, site morphometry, and observational setup. The comparison of bottom up versus ISL is inconclusive; in some conditions agreement appears promising, and in others it does not. The question has not been proven or disproven. It may be too ambitious to test the concept at a real-world site.

Corresponding author address: J. A. Salmond, School of Environment, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. E-mail: j.salmond@auckland.ac.nz
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