Using Satellite Remote Sensing, Field Observations and WRF/Single-Layer Urban Canopy Model Simulation to Analyze the Oklahoma City UHI Effect

AbstractNumerical simulations without hydrological processes tend to overestimate the near-surface temperatures over urban areas. This is presumably due to underestimation of surface latent heat flux. To test this hypothesis, the existing single-layer urban canopy model (SLUCM) within the Weather Research and Forecasting Model is evaluated over Houston, Texas. Three simulations were conducted during 24–26 August 2000. The simulations include the use of the default “BULK” urban scheme, the SLUCM without hydrological processes, and the SLUCM with hydrological processes. The results show that the BULK scheme was least accurate, and it overestimated the near-surface temperatures and winds over the urban regions. In the presence of urban hydrological processes, the SLUCM underestimates these parameters. An analysis of the surface heat fluxes suggests that the error in the BULK scheme is due to a lack of moisture at the urban surface, whereas the error in the SLUCM with hydrological processes is due to increases in moisture at the urban surface. These results confirm earlier studies in which changes in near-surface temperature were primarily due to the changes in the turbulent (latent and sensible heat) fluxes in the presence of hydrological processes. The contribution from radiative flux was about one-third of that from turbulent flux. In the absence of hydrological processes, however, the results indicate that the changes in radiative flux contribute more to the near-surface temperature changes than the turbulent heat flux. The implications of these results are discussed.

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Modeling carbon dioxide exchange in a single-layer urban canopy model

Building and Environment ◽

10.1016/j.buildenv.2020.107243 ◽

2020 ◽

Vol 184 ◽

pp. 107243 ◽

Cited By ~ 1

Author(s):

Peiyuan Li ◽

Zhi-Hua Wang

Keyword(s):

Carbon Dioxide ◽

Single Layer ◽

Urban Canopy ◽

Carbon Dioxide Exchange ◽

Urban Canopy Model ◽

Canopy Model

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Evaluation and Parameter-Sensitivity Study of a Single-Layer Urban Canopy Model (SLUCM) with Measurements in Nanjing, China

Journal of Hydrometeorology ◽

10.1175/jhm-d-13-0129.1 ◽

2014 ◽

Vol 15 (3) ◽

pp. 1078-1090 ◽

Cited By ~ 9

Author(s):

Wenjing Zhao ◽

Ning Zhang ◽

Jianning Sun ◽

Jun Zou

Keyword(s):

Heat Flux ◽

Energy Balance ◽

Surface Energy ◽

Surface Energy Balance ◽

Sensible Heat Flux ◽

Single Layer ◽

Urban Canopy ◽

Sensible Heat ◽

Urban Canopy Model ◽

Canopy Model

Abstract An offline single-layer urban canopy model (SLUCM) was driven by the surface energy balance observations in winter in Nanjing, China, to evaluate the capability of the model to simulate the urban surface energy balance. The results of the evaluation suggest that the simulated daytime net radiation is approximately 20% lower than the observed and display relatively high systematic error, which is due to the relatively poor capacity of the model to simulate the daytime longwave radiation (which is underestimated by approximately 35%). By contrast, the simulated sensible heat flux shows mainly unsystematic error. Moreover, the one-at-a-time method is used to conduct a sensitivity analysis of the model parameters. The sensitivity analysis demonstrates that the major factors affecting the surface energy balance are the albedo, the thermal conductivity, and the roof and wall volumetric heat capacity. The influences of the shape of the street canyon and the average height of buildings are relatively weaker. The effects of the albedo on the fluxes are nearly linear. The effects of the thermal parameters are approximately logarithmic. Furthermore, the simulated sensible heat flux in the SLUCM is insensitive to the morphological parameters of the buildings.

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A Simple Single-Layer Urban Canopy Model For Atmospheric Models: Comparison With Multi-Layer And Slab Models

Boundary-Layer Meteorology ◽

10.1023/a:1019207923078 ◽

2001 ◽

Vol 101 (3) ◽

pp. 329-358 ◽

Cited By ~ 676

Author(s):

Hiroyuki Kusaka ◽

Hiroaki Kondo ◽

Yokihiro Kikegawa ◽

Fujio Kimura

Keyword(s):

Single Layer ◽

Urban Canopy ◽

Urban Canopy Model ◽

Atmospheric Models ◽

Models Comparison ◽

Canopy Model

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A New Single-Layer Urban Canopy Model for Use in Mesoscale Atmospheric Models

Journal of Applied Meteorology and Climatology ◽

10.1175/2011jamc2665.1 ◽

2011 ◽

Vol 50 (9) ◽

pp. 1773-1794 ◽

Cited By ~ 47

Author(s):

Young-Hee Ryu ◽

Jong-Jin Baik ◽

Sang-Hyun Lee

Keyword(s):

Energy Balance ◽

Surface Energy ◽

Surface Energy Balance ◽

Single Layer ◽

Urban Canopy ◽

Heat Fluxes ◽

Urban Surface ◽

Urban Canopy Model ◽

Canopy Model ◽

Urban Surface Energy Balance

AbstractA new single-layer urban canopy model for use in mesoscale atmospheric models is developed and validated. The urban canopy model represents a built-up area as a street canyon, two facing buildings, and a road. In this model, the two facing walls are divided into sunlit and shaded walls on the basis of solar azimuth angle and canyon orientation, and individual surface temperature and energy budget are calculated for each wall. In addition, for better estimation of turbulent energy exchange within the canyon, a computational fluid dynamics model is employed to incorporate the effects of canyon aspect ratio (height-to-width ratio) and reference wind direction on canyon wind speed. The model contains the essential physical processes occurring in an urban canopy: absorption and reflection of shortwave and longwave radiation, exchanges of turbulent energy and water between surfaces (roof, two facing walls, and road) and adjacent air, and heat transfer by conduction through substrates. The developed urban canopy model is validated using datasets obtained at two urban sites: Marseille, France, and Basel, Switzerland. The model satisfactorily reproduces canyon air temperatures, surface temperatures, net radiation, sensible heat fluxes, latent heat fluxes, and storage heat fluxes for both sites. Extensive experiments are conducted to examine the sensitivities of the urban surface energy balance to meteorological factors and urban surface parameters. The reference wind speed is found to be a more crucial meteorological factor than the reference air temperature in altering urban surface energy balance, especially for weak winds. The urban surface energy balance is most sensitive to the roof albedo among urban surface parameters. The roof fraction, canyon aspect ratio, and ratio of roughness length for momentum to that for heat for the roof play important roles in altering urban surface energy balance.

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Application of MORUSES single‐layer urban canopy model in a tropical city: Results from Singapore

Quarterly Journal of the Royal Meteorological Society ◽

10.1002/qj.3694 ◽

2019 ◽

Vol 146 (727) ◽

pp. 576-597 ◽

Cited By ~ 3

Author(s):

Andrés Simón‐Moral ◽

Anurag Dipankar ◽

Matthias Roth ◽

Claudio Sánchez ◽

Erik Velasco ◽

...

Keyword(s):

Single Layer ◽

Urban Canopy ◽

Urban Canopy Model ◽

Canopy Model

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Sensitivity of Simulated Urban–Atmosphere Interactions in Oklahoma City to Urban Parameterization

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-16-0223.1 ◽

2017 ◽

Vol 56 (5) ◽

pp. 1405-1430 ◽

Cited By ~ 2

Author(s):

Larissa J. Reames ◽

David J. Stensrud

Keyword(s):

Urban Areas ◽

Urban Canopy ◽

Oklahoma City ◽

Surface Model ◽

Urban Canopy Model ◽

Near Surface ◽

Modeling Studies ◽

Suburban Cities ◽

The City ◽

Canopy Model

AbstractThe world’s population is increasingly concentrated in large urban areas. Many observational and modeling studies have explored how these large, population-dense cities modify local and mesoscale atmospheric phenomena. These modeling studies often use an urban canopy model to parameterize urban surfaces. However, it is unclear whether this approach is appropriate for more suburban cities, such as those found in the Great Plains. Thus, the Weather Research and Forecasting Model was run for a week over Oklahoma City, Oklahoma, and results were compared with observations. Overall, four configurations were examined. Two simulations used the Noah LSM, one with all urban areas removed (CTRL), and the other with urban areas parameterized by a modified Noah land surface model with three urban categories (LSMMOD). Additional simulations utilized a single-layer urban canopy model (SLUCM) either with default urban fraction values (SLUCM1) or with urban fractions taken from the National Land Cover Database (SLUCM2). Results from the three urban runs compared favorably to high-density temperature observations of the urban heat island. The SLUCM1 run was the most realistic, although the urban fractions applied were the least representative of Oklahoma City. All urban runs also produced a drier and deeper planetary boundary layer over the city. The prediction of near-surface winds was most problematic, with the two SLUCM runs unable to correctly reproduce reduced wind speeds over the city. The modified Noah LSM provided best overall agreement with observations and represents a reasonable option for simulating the urban effects of more-suburban cities.

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