Urban Meteorology Rick Peltier Sangil Lee Chris Hennigan Ehsan Arhami

The Urban Heat Island

Urban Heat Island The increased air temperatures in urban areas as contrasted to the cooler surrounding rural areas. The increased air temperatures in urban areas as contrasted to the cooler surrounding rural areas. Source: Lawrence Berkeley National Lab.

Rapid Urbanization Lack of surface water (soil water) and vegetation. Low short-wave reflectivity (albedo). increased heat release. Source: EPA & Rice University

Mesoscale circulation and convection Source: NASA Global Hydrology and Climate Center Stagnant condition Gradient wind condition

Mesoscale circulation and convection Source: NASA Global Hydrology and Climate Center Convective precipitation associated with the excess heat.

Mesoscale circulation and convection Source: NASA Global Hydrology and Climate Center Increased precipitation (7 ~ 50% greater). Maximum rainfall rates (48 ~116 % greater) downwind of major cities.  Mean monthly rainfall during the warmer season (May ~ Sept.) from 1998~2000.

Air Quality Issues Urban heat islands are not only uncomfortably hot, they are also smoggier. (i.e., the incidence of smog increases by 3% per °F above 70°F.) Source: Heat Island Group, Lawrence Berkeley National Lab. & NASA Global Hydrology and Climate Center

Topographical Effects of Urban Area Urban Pollution Dispersion Picture from: corbis.com

Overview Effect of Topography on Flow Effect of Topography on Flow Urban Boundary Layer Urban Boundary Layer Urban Canopy Urban Canopy

Geographically Modified Flow Internal Boundary Layer fetch Pictures from: Stull book

Urban Boundary Layer Picture from: Fisher et al. report

Sketch of Urban Boundary Layer and Urban Plume Pictures from: Stull book

Layers Within The Urban Boundary Layer Picture from: Stull book

What Happens to Wind Profile Between the Buildings Wind VelocityPollutant Distribution 2 m/s Recirculation eddy 10% of free stream velocity Pictures from: Gerdes et al., paper

Pollutant Dispersion in Urban Street Canopies Large reverse Pictures from: Xia et al., paper

Identical Building Upstream Low Building Low Building High Building High Building Pictures from: Xia et al., paper

Urban Meteorology – case studies Tehran, Iran Tehran, Iran Graz, Austria Graz, Austria Sydney, Australia Sydney, Australia Atlanta, GA Atlanta, GA

Tehran, Iran From

Tehran, Iran From Alborz Mountains City center

From Asadollah-Fardi Tehran Pollution

Valley Pollution Dispersion From

Valley Circulation From

Graz, Austria From

Graz, Austria From

Graz Pollution Pollution Event – January 7, 1991 Pollutant Max Concentration NO ppm NO ppm CO 8 ppm SO ppm From Sturm, Almbauer, Kunz

Mountain Lee Phenomenon From

Sydney, Australia From

Sydney, Australia From

Sydney Pollution From 1980 to 1992, Sydney averaged 20 days per year with peak O 3 > 80 ppb From 1980 to 1992, Sydney averaged 20 days per year with peak O 3 > 80 ppb Diurnal O 3 variation Diurnal O 3 variation From Physick

Sea Breeze From USA Today

Atlanta, GA Atlanta Supersite, 1999 UGA Agricultural Research Station – Griffin, GA

The Urban Environment - Overview Regional and local scale models often do not predict very local conditions Regional and local scale models often do not predict very local conditions Urban-Specific Problems Urban-Specific Problems Indoor/Outdoor correlations Indoor/Outdoor correlations Socioeconomic status (SES) Socioeconomic status (SES)

Urban Modeling

Urban-Specific Problems Local (unmodelled/unmeasured) Exposures Local (unmodelled/unmeasured) Exposures Urban Heat Island Urban Heat Island Humidity/Heat Index Humidity/Heat Index Stress Stress Pollutant Specifics and the Urban Environment Pollutant Specifics and the Urban Environment

Urban Health – Air Toxics Typically increased (small) local sources of air toxics Typically increased (small) local sources of air toxics 1,3-Butadiene, benzene, etc1,3-Butadiene, benzene, etc Very source specific Very source specific

Indoor/Outdoor “Meteorology” Harsh Urban Environment Mitigation (A/C, etc.) Harsh Urban Environment Mitigation (A/C, etc.) Meteorology drives people inside/outside Meteorology drives people inside/outside Meteorological Phenomena sensitivity Meteorological Phenomena sensitivity

Urban Health - SES Urban sites typically populated by many low-SES families Urban sites typically populated by many low-SES families Low SES = increased susceptibility Low SES = increased susceptibility

Tehran – ~12,000 persons/sq km Tehran – ~12,000 persons/sq km Graz – 4730 persons/sq km Graz – 4730 persons/sq km Sydney – 2474 persons/sq km Sydney – 2474 persons/sq km Atlanta – 1303 persons/sq km Atlanta – 1303 persons/sq km Our Urban Environment?

Summary/Conclusions Urban Heat Island Urban Heat Island Urban Topography Urban Topography Case Studies of the Urban Environment Case Studies of the Urban Environment Applications in the Urban Environment Applications in the Urban Environment

References 1. Stull R. B., An introduction to boundary layer meteorology, Kluwer Academic Publishers, 1988, Fisher B., Kukkonen J. and Schatzmann M., Meteorology applied to urban air pollution problems COST 715, Report from atmosphericenvironment website. 3. Gerdes, F., Olivari, D., Analysis of pollutant dispersion in an urban street canyon, Journal of Wind Engineering and Industrial Aerodynamics 82, Xia J. and Leung D.Y.C., Pollutant dispersion in urban street canopies, Atmospheric Environment 35 (2001) Asadollah-Fardi, G. “Air Quality Management in Tehran,” 7. Physick, W.L. “Photochemical smog studies in Australian cities,” Urban Air Pollution, Volume 2. ed. H. Power and N. Moussiopoulos. Computational Mechanics Publications, Sturm, P.J., R. A. Almbauer, and R. Kunz. “Air quality study for the city of Graz, Austria,” Urban Air Pollution, Volume1. ed. H. Power, N. Moussiopoulos, and C.A. Brebbia. Computational Mechanics Publications, Heat Island Group, Lawrence Berkeley National Lab. & NASA Global Hydrology and Climate Center

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