scholarly journals Surface and Atmospheric Driven Variability of the Single‐Layer Urban Canopy Model Under Clear‐Sky Conditions Over London

2020 ◽  
Vol 125 (14) ◽  
Author(s):  
A. Tsiringakis ◽  
A. A. M. Holtslag ◽  
Sue Grimmond ◽  
G. J. Steeneveld
Keyword(s):  
Single Layer ◽  
Urban Canopy ◽  
Urban Canopy Model ◽  
Clear Sky ◽  
Sky Conditions ◽  
Canopy Model

scholarly journals Relative Role of Turbulent and Radiative Flux on the Near-Surface Temperature in a Single-Layer Urban Canopy Model over Houston

2017 ◽  
Vol 56 (8) ◽  
pp. 2173-2187 ◽  
Author(s):  
James Brownlee ◽  
Pallav Ray ◽  
Mukul Tewari ◽  
Haochen Tan
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Single Layer ◽  
Urban Canopy ◽  
Heat Fluxes ◽  
Radiative Flux ◽  
Hydrological Processes ◽  
Urban Canopy Model ◽  
Near Surface ◽  
Canopy Model

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.

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

2014 ◽  
Vol 15 (3) ◽  
pp. 1078-1090 ◽  
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.

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

2001 ◽  
Vol 101 (3) ◽  
pp. 329-358 ◽  
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

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

2011 ◽  
Vol 50 (9) ◽  
pp. 1773-1794 ◽  
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.

The Single-column Urban Boundary Layer Intercomparison Modelling Experiment (SUBLIME): results of revised recipe

2020 ◽  
Author(s):  
Gert-Jan Steeneveld ◽  
Aristofanis Tsiringakis ◽  
Keyword(s):  
Boundary Layer ◽  
Weather Prediction ◽  
Urban Canopy ◽  
Urban Boundary Layer ◽  
Urban Canopy Model ◽  
Clear Sky ◽  
The Sublime ◽  
External Forcings ◽  
Single Column ◽  
Canopy Model

<p>Models for weather and climate have been actively populated with urban canopy models in the last decade. Urban canopy models are available with different levels of complexity. In an earlier study several urban canopy models have been evaluated in offline mode (Grimmond et al. 2011). However, in reality these schemes operate within a numerical weather prediction model, and are coupled with the atmospheric boundary layer. Within the SUBLIME model intercomparison study, single-column models equipped with urban canopy models are evaluated against observations for a clear sky case over London. As such we aim to unravel whether model sensitivity for urban morphological parameters is similar in coupled and uncoupled model. Moreover, the SUBLIME project provides a benchmark for future model evaluation and further development. The SUBLIME experiment consists of a forecast task over a 54 hour period (23-25 July 2012), during which clear sky conditions persisted over London. It consists of two main stages, firstly an offline urban canopy model run, to determine how the surface scheme performs. This is followed by a run in which the urban canopy model is coupled to a single-column model to simulate the coupling to the urban boundary layer. Model forcing data were provided by flux tower, LIDAR and radiosonde observations. Additional external forcings for geostrophic wind speed and advection of heat, moisture and momentum which could not be directly observed were simulated using, 3-D WRF (Weather Research and Forecasting model) model runs. This presentation will discuss the modelling results using the new revised external forcings. We evaluate model outcomes against surface radiation and energy balance observations for both stages. For the second stage, modelled vertical profiles of wind, temperature and humidity as well as boundary-layer height are compared against observations and between models. Finally, differences in model results are identified and the physical processes responsible for these are explored using process diagrams.</p>

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

2019 ◽  
Vol 146 (727) ◽  
pp. 576-597 ◽  
Author(s):  
Andrés Simón‐Moral ◽  
Anurag Dipankar ◽  
Matthias Roth ◽  
Claudio Sánchez ◽  
Erik Velasco ◽  
...  
Keyword(s):  
Single Layer ◽  
Urban Canopy ◽  
Urban Canopy Model ◽  
Canopy Model

The implementation of biofiltration systems, rainwater tanks and urban irrigation in a single-layer urban canopy model

Urban Climate ◽  
2014 ◽  
Vol 10 ◽  
pp. 148-170 ◽  
Author(s):  
M. Demuzere ◽  
A.M. Coutts ◽  
M. Göhler ◽  
A.M. Broadbent ◽  
H. Wouters ◽  
...  
Keyword(s):  
Single Layer ◽  
Urban Canopy ◽  
Urban Canopy Model ◽  
Urban Irrigation ◽  
Canopy Model ◽  
Rainwater Tanks
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