Modeling the diurnal variability of effective albedo for cities

David J. Sailor, Hongli Fan

Research output: Contribution to journalArticle

67 Scopus citations

Abstract

As applied to urban domains, traditional representations of surface albedo do not adequately account for the complex radiative exchange within the urban canopy. In this paper, we present a simple radiation model that takes into account the diurnal variation of short-wave radiation, including the effects of surface shading and radiation exchange among surfaces within the urban canopy. The model has been validated using prior observational studies and used to calculate the time-dependent effective short-wave reflectivity of hypothetical and case study urbanized grid cells, as well as the daily energy-weighted average of these parameters. Monte Carlo style simulations for four distinct urban land use categories indicate that the nadir-view albedo (NVA) typically underestimates daily solar radiative loads by 11-22%, depending upon the land use. We have also found that fairly detailed land-use classification schemes introduce large uncertainties in NVA. In fact, the uncertainty in albedo values for any urban land use category is comparable to the albedo variability across the various urban land use classifications. Furthermore, the magnitude of the diurnal variability of effective albedo for cities is large enough that neglecting it could adversely impact the ability to resolve the energy balance and circulation patterns associated with the urban heat island.

Original languageEnglish (US)
Pages (from-to)713-725
Number of pages13
JournalAtmospheric Environment
Volume36
Issue number4
DOIs
StatePublished - Feb 5 2002
Externally publishedYes

Keywords

  • Albedo
  • Energy balance
  • Mesoscale meteorology
  • Radiation
  • Urban heat island

ASJC Scopus subject areas

  • Environmental Science(all)
  • Atmospheric Science

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