Daytime cooling efficiency and diurnal energy balance in Phoenix, Arizona, USA

Ariane Middel, Anthony J. Brazel, Shai Kaplana, Soe Myint

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Summer daytime cooling efficiency of various land cover is investigated for the urban core of Phoenix, Arizona, using the Local-Scale Urban Meteorological Parameterization Scheme (LUMPS). We examined the urban energy balance for 2 summer days in 2005 to analyze the daytime cooling-water use tradeoff and the timing of sensible heat reversal at night. The plausibility of the LUMPS model results was tested using remotely sensed surface temperatures from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery and reference evapotranspiration values from a meteorological station. Cooling efficiency was derived from sensible and latent heat flux differences. The time when the sensible heat flux turns negative (sensible heat flux transition) was calculated from LUMPS simulated hourly fluxes. Results indicate that the time when the sensible heat flux changes direction at night is strongly influenced by the heat storage capacity of different land cover types and by the amount of vegetation. Higher heat storage delayed the transition up to 3 h in the study area, while vegetation expedited the sensible heat reversal by 2 h. Cooling efficiency index results suggest that overall, the Phoenix urban core is slightly more efficient at cooling than the desert, but efficiencies do not increase much with wet fractions higher than 20%. Industrial sites with high impervious surface cover and low wet fraction have negative cooling efficiencies. Findings indicate that drier neighborhoods with heterogeneous land uses are the most efficient landscapes in balancing cooling and water use in Phoenix. However, further factors such as energy use and human vulnerability to extreme heat have to be considered in the cooling-water use tradeoff, especially under the uncertainties of future climate change.

Original languageEnglish (US)
Pages (from-to)21-34
Number of pages14
JournalClimate Research
Volume54
Issue number1
DOIs
StatePublished - Aug 3 2012

Fingerprint

Energy balance
energy balance
sensible heat flux
Cooling
cooling
Heat flux
Parameterization
water use
parameterization
Heat storage
cooling water
Cooling water
land cover
Evapotranspiration
ASTER
vegetation
Latent heat
summer
Radiometers
latent heat flux

Keywords

  • Cooling efficiency
  • Land cover
  • LUMPS
  • Phoenix
  • Remote sensing
  • Sensible heat flux transition
  • Urban climate
  • Urban heat island

ASJC Scopus subject areas

  • Atmospheric Science
  • Environmental Science(all)
  • Environmental Chemistry

Cite this

Daytime cooling efficiency and diurnal energy balance in Phoenix, Arizona, USA. / Middel, Ariane; Brazel, Anthony J.; Kaplana, Shai; Myint, Soe.

In: Climate Research, Vol. 54, No. 1, 03.08.2012, p. 21-34.

Research output: Contribution to journalArticle

Middel, Ariane ; Brazel, Anthony J. ; Kaplana, Shai ; Myint, Soe. / Daytime cooling efficiency and diurnal energy balance in Phoenix, Arizona, USA. In: Climate Research. 2012 ; Vol. 54, No. 1. pp. 21-34.
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