Systematic Comparison of the Influence of Cool Wall versus Cool Roof Adoption on Urban Climate in the Los Angeles Basin

Zhang, Jiachen; Mohegh, Arash; Li, Yun; Levinson, Ronnen; Ban-Weiss, George

doi:10.1021/acs.est.8b00732

Cited by 35 publications

(42 citation statements)

References 42 publications

(50 reference statements)

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“…Where NUDAPT data are unavailable, we use aver-age building and road morphology for three urban categories from the Los Angeles Region Imagery Acquisition Consortium (LARIAC). Details on the generation of averaged urban morphology parameters from real-world GIS datasets can be found in Zhang et al (2018a). For the other parameters in the UCM (e.g., anthropogenic latent heat, surface emissivity), we use default WRF settings documented in file URB-PARM.TBL.…”

Section: Land Surface Property Characterization and Irrigation Paramementioning

confidence: 99%

Effects of urbanization on regional meteorology and air quality in Southern California

Zhang

Sailor

et al. 2019

Atmos. Chem. Phys.

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Urbanization has a profound influence on regional meteorology and air quality in megapolitan Southern California. The influence of urbanization on meteorology is driven by changes in land surface physical properties and land surface processes. These changes in meteorology in turn influence air quality by changing temperature-dependent chemical reactions and emissions, gas-particle phase partitioning, and ventilation of pollutants. In this study we characterize the influence of land surface changes via historical urbanization from before human settlement to the present day on meteorology and air quality in Southern California using the Weather Research and Forecasting Model coupled to chemistry and the single-layer urban canopy model (WRF-UCM-Chem). We assume identical anthropogenic emissions for the simulations carried out and thus focus on the effect of changes in land surface physical properties and land surface processes on air quality. Historical urbanization has led to daytime air temperature decreases of up to 1.4 K and evening temperature increases of up to 1.7 K. Ventilation of air in the LA basin has decreased up to 36.6 % during daytime and increased up to 27.0 % during nighttime. These changes in meteorology are mainly attributable to higher evaporative fluxes and thermal inertia of soil from irrigation and increased surface roughness and thermal inertia from buildings. Changes in ventilation drive changes in hourly NO x concentrations with increases of up to 2.7 ppb during daytime and decreases of up to 4.7 ppb at night. Hourly O 3 concentrations decrease by up to 0.94 ppb in the morning and increase by up to 5.6 ppb at other times of day. Changes in O 3 concentrations are driven by the competing effects of changes in ventilation and precursor NO x concentrations. PM 2.5 concentrations show slight increases during the day and decreases of up to 2.5 µg m −3 at night. Process drivers for changes in PM 2.5 include modifications to atmospheric ventilation and temperature, which impact gas-particle phase partitioning for semi-volatile compounds and chemical reactions. Understanding process drivers related to how land surface changes effect regional meteorology and air quality is crucial for decision-making on urban planning in megapolitan Southern California to achieve regional climate adaptation and air quality improvements.Published by Copernicus Publications on behalf of the European Geosciences Union.

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Section: Land Surface Property Characterization and Irrigation Paramementioning

confidence: 99%

Effects of urbanization on regional meteorology and air quality in Southern California

Zhang

Sailor

et al. 2019

Atmos. Chem. Phys.

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“…Where NUDAPT data are unavailable, we use average building and road morphology for three urban categories from the Los Angeles Region Imagery Acquisition Consortium (LARIAC). Details on the generation of averaged urban morphology parameters from real-world GIS datasets can be found in Zhang et al (2018a). Note that the original gaseous dry deposition code based on Wesely (1989) is only compatible with the default 24-category U.S. Geological Survey (USGS) global land cover map.…”

Section: Land Surface Property Characterization and Process Parametermentioning

confidence: 99%

Effects of Urbanization on Regional Meteorology and Air Quality in Southern California

Li¹,

Zhang²,

Sailor³

et al. 2018

Preprint

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Abstract. Urbanization has a profound influence on regional meteorology and air quality in megapolitan Southern California. The influence of urbanization on meteorology is driven by changes in land surface physical properties and land surface processes. These changes in meteorology in turn influence air quality by changing temperature-dependent chemical reactions and emissions, gas-particle phase partitioning, and ventilation of pollutants. In this study we characterize the influence of historical urbanization from before human settlement to present-day on meteorology and air quality in Southern California using the Weather Research and Forecasting Model coupled to chemistry and the single-layer urban canopy model (WRF/Chem-UCM). We assume identical anthropogenic emissions for the simulations carried out, and thus focus on the effect of changes in land surface physical properties and land surface processes on air quality. Historical urbanization has led to daytime air temperature decreases of up to 1.4&#8201;K, and evening temperature increases of up to 1.7&#8201;K. Ventilation of air in the LA basin has decreased up to 36.6&#8201;% during daytime and increased up to 27.0&#8201;% during nighttime. These changes in meteorology are mainly attributable to higher evaporative fluxes from irrigation, higher thermal inertia from irrigation and building materials, and increased surface roughness from buildings. Changes in ventilation drive changes in hourly NOx concentrations with increases of up to 2.7&#8201;ppb during daytime and decreases of up to 4.7&#8201;ppb at night. Hourly O3 concentrations decrease by up to 0.94&#8201;ppb in the morning, and increase by up to 5.6&#8201;ppb at other times of day. Changes in O3 concentrations are driven by the competing effects of changes in ventilation and precursor NOx concentrations. PM2.5 concentrations show slight increases during the day, and decreases of up to 2.5&#8201;&#956;g/m3 at night. Processes drivers for changes in PM2.5 include modifications to atmospheric ventilation, and temperature, which impacts gas-particle phase partitioning for semi-volatile compounds and chemical reactions. Understanding processes drivers for how land surface changes effect regional meteorology and air quality is crucial for decision making on urban planning in megapolitan Southern California to achieve regional climate adaptation and air quality improvements.

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“…Raising urban albedo (solar reflectance) increases the fraction of incident sunlight returned to outer space, cooling cities and their buildings [1,2]. It can also reduce atmospheric temperature via negative radiative forcing, abating global warming [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Design, characterization, and fabrication of solar-retroreflective cool-wall materials

Levinson

Chen

Slack

et al. 2020

Solar Energy Materials and Solar Cells

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Raising urban albedo increases the fraction of incident sunlight returned to outer space, cooling cities and their buildings. We evaluated the angular distribution of solar radiation incident on exterior walls in 17 U.S. climates to develop performance parameters for solar-retroreflective walls, then applied firstprinciple physics and ray-tracing simulations to explore designs. Our analysis indicates that retroreflective walls must function at large incidence angles to reflect a substantial portion of summer sunlight, and that this will be difficult to attain with materials that rely on total internal reflection. Gonio-spectrophotometer measurements of the solar spectral bi-directional reflectivity of a bicycle reflector showed little to no retroreflection at large incidence angles. Visual comparison of retroreflection to specular first-surface reflection for four different retroreflective safety films using violet and green lasers suggest their retroreflection to be no greater than 0.09 at incidence angles up to 45°, and no greater than 0.30 at incidence angles of up to 70°. Attempts to produce a two-surface retroreflector with orthogonal mirror grooves by cutting and polishing an aluminum block indicate that residual surface roughness impedes retroreflection. Ongoing efforts focus on forming orthogonal surfaces with aluminized Mylar film, a material with very high specular reflectance across the solar spectrum. We investigated (1) folding or stamping a free film; (2) adhering the film to a pre-shaped substrate; and (3) attaching the film to a flat ductile substrate, then shaping. The latter two methods were more successful but produced imperfect right angles.

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Systematic Comparison of the Influence of Cool Wall versus Cool Roof Adoption on Urban Climate in the Los Angeles Basin

Cited by 35 publications

References 42 publications

Effects of urbanization on regional meteorology and air quality in Southern California

Effects of urbanization on regional meteorology and air quality in Southern California

Effects of Urbanization on Regional Meteorology and Air Quality in Southern California

Design, characterization, and fabrication of solar-retroreflective cool-wall materials

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