A Sensitivity Study of the Urban Effect on a Regional-Scale Model: An Idealized Case

Conference · Tue May 30 04:00:00 EDT 2000

OSTI ID:791718

Chin, H N.S. ^[1]; Leach, M J; Brown, M J

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1. LLNL

Urban infrastructure impacts the surface and atmospheric properties, such as wind, temperature, turbulence and radiation budgets. The well-recognized urban heat island phenomenon, characterized by the temperature contrast between the city and the surrounding rural area, is one such impact. Many field experiments have been conducted to study the urban heat island effect, which is typically most intense under clear sky and weak ambient wind conditions at night. In some cases, a cool island may even exist during the day. To consider these urban effects in a numerical model with horizontal grid resolution on the order of kilometers, some sort of parameterization is required to account for the sub-grid building impacts on these effects. To this end, Brown and Williams (1998) have developed an urban parameterization by extending Yamada's (1982) forest canopy scheme to include drag, turbulent production, anthropogenic and rooftop heating effects, and radiation balance in a mesoscale model. In this study, we further modify this urban parameterization by adding the rooftop surface energy equation to eliminate a simplifying assumption that the rooftop is at the same temperature as the air. The objective of this work is to assess the impact of individual process of this modified urban canopy parameterization for the urban heat island phenomenon.

• Research Organization: Lawrence Livermore National Lab., CA (US)
• Sponsoring Organization: USDOE Office of Defense Programs (DP) (US)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 791718
• Report Number(s): UCRL-JC-139167
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
FORESTS
HEATING
PRODUCTION
RADIATIONS
RESOLUTION
RURAL AREAS
SENSITIVITY
SURFACE ENERGY
TURBULENCE