scholarly journals Advantages of using a fast urban canopy model as compared to a full mesoscale model to simulate the urban heat island of Barcelona

2016 ◽  
Author(s):  
M. García-Díez ◽  
D. Lauwaet ◽  
H. Hooyberghs ◽  
J. Ballester ◽  
K. De Ridder ◽  
...  
Keyword(s):  
Simple Model ◽  
Land Surface ◽  
Climate Model ◽  
Mesoscale Model ◽  
Urban Climate ◽  
Urban Canopy ◽  
Forecast Model ◽  
Reanalysis Data ◽  
Urban Canopy Model ◽  
Canopy Model

Abstract. As most of the population lives in urban environments, the simulation of the urban climate has become a key problem in the framework of the climate change impact assessment. However, the high computational power required by these simulations is a severe limitation. Here we present a study on the performance of a Urban Climate Model (UrbClim), designed to be several orders of magnitude faster than a full-fledge mesoscale model. The simulations are validated with station data and with land surface temperature observations retrieved by satellites. To explore the advantages of using a simple model like UrbClim, the results are compared with a simulation carried out with a state-of-the-art mesoscale model, the Weather Research and Forecasting model, using an Urban Canopy model. The effect of using different driving data is explored too, by using both relatively low resolution reanalysis data (70 km) and a higher resolution forecast model (15 km). The results show that, generally, the performance of the simple model is comparable to or better than the mesoscale model. The exception are the winds and the day-to-day correlation in the reanalysis driven run, but these problems disappear when taking the boundary conditions from the higher resolution forecast model.

scholarly journals Advantages of using a fast urban boundary layer model as compared to a full mesoscale model to simulate the urban heat island of Barcelona

2016 ◽  
Vol 9 (12) ◽  
pp. 4439-4450 ◽  
Author(s):  
Markel García-Díez ◽  
Dirk Lauwaet ◽  
Hans Hooyberghs ◽  
Joan Ballester ◽  
Koen De Ridder ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Simple Model ◽  
Wind Speed ◽  
Mesoscale Model ◽  
Urban Climate ◽  
Urban Canopy ◽  
Forecast Model ◽  
Heat Island ◽  
Layer Model ◽  
Urban Heat

Abstract. As most of the population lives in urban environments, the simulation of the urban climate has become a key problem in the framework of the climate change impact assessment. However, the high computational power required by high-resolution (sub-kilometre) fully coupled land–atmosphere simulations using urban canopy parameterisations is a severe limitation. Here we present a study on the performance of UrbClim, an urban boundary layer model designed to be several orders of magnitude faster than a full-fledged mesoscale model. The simulations are evaluated with station data and land surface temperature observations from satellites, focusing on the urban heat island (UHI). To explore the advantages of using a simple model like UrbClim, the results are compared with a simulation carried out with a state-of-the-art mesoscale model, the Weather Research and Forecasting Model, which includes an urban canopy model. This comparison is performed with driving data from ERA-Interim reanalysis (70 km). In addition, the effect of using driving data from a higher-resolution forecast model (15 km) is explored in the case of UrbClim. The results show that the performance of reproducing the average UHI in the simple model is generally comparable to the one in the mesoscale model when driven with reanalysis data (70 km). However, the simple model needs higher-resolution data from the forecast model (15 km) to correctly reproduce the variability of the UHI at a daily scale, which is related to the wind speed. This lack of accuracy in reproducing the wind speed, especially the sea-breeze daily cycle, which is strong in Barcelona, also causes a warm bias in the reanalysis driven UrbClim run. We conclude that medium-complexity models as UrbClim are a suitable tool to simulate the urban climate, but that they are sensitive to the ability of the input data to represent the local wind regime. UrbClim is a well suited model for impact and adaptation studies at city scale without high computing requirements, but does not replace the need for mesoscale atmospheric models when the focus is on the two-way interactions between the city and the atmosphere.

scholarly journals STUDY ON URBAN CLIMATE ANALYSIS BASED ON MESO-SCALE CLIMATE MODEL INCORPORATED WITH THE URBAN CANOPY MODEL

2005 ◽  
Vol 70 (592) ◽  
pp. 75-82 ◽  
Author(s):  
Kazuya HARAYAMA ◽  
Ryozo OOKA ◽  
Shuzo MURAKAMI ◽  
Shinji YOSHIDA ◽  
Masahiro SETOJIMA ◽  
...  
Keyword(s):  
Climate Model ◽  
Urban Climate ◽  
Urban Canopy ◽  
Urban Canopy Model ◽  
Climate Analysis ◽  
Canopy Model ◽  
Meso Scale

scholarly journals Intercomparison between the Integrated Urban land Model and the Noah Urban Canopy Model

2020 ◽  
Author(s):  
Chunlei Meng ◽  
Junxia Dou
Keyword(s):  
Heat Flux ◽  
Solar Radiation ◽  
Human Activity ◽  
Land Surface ◽  
Land Surface Model ◽  
Urban Canopy ◽  
Urban Land ◽  
Surface Model ◽  
Urban Canopy Model ◽  
Canopy Model

Abstract. Urban land surface model (ULSM) is an important tool to study the climatic effect of human activity. Now there are two main methods to parameterize the effects of human activity, the coupling method and the integrating method. For the coupled method, the urban canopy model (UCM) was developed and coupled with the land surface model for the natural land surfaces. For the integrated method, the urban land surface model was built directly based on the traditional land surface model. In this paper, the Noah Single Layer Urban Canopy Model (Noah/SLUCM) and the Integrated Urban land Model (IUM) were compared using the observed fluxes data at the 325-meter meteorology tower in Beijing. Through the comparison, the key factors and physical processes of the urban land surface model which have significant impact on the performance of ULSM were found out. The results indicate that the absorbed solar radiation of urban surface was reduced by the solar radiation scattering, the absorption of building roof and wall, and the shading effect of urban canopy and tall buildings. Urban surface roughness length and friction velocity are important in urban sensible heat flux simulation. Urban water balance and impervious surface evaporation (ISE) are important in urban latent heat flux simulation.

scholarly journals Impact of an improved WRF urban canopy model on diurnal air temperature simulation over northern Taiwan

2016 ◽  
Vol 16 (3) ◽  
pp. 1809-1822 ◽  
Author(s):  
Chuan-Yao Lin ◽  
Chiung-Jui Su ◽  
Hiroyuki Kusaka ◽  
Yuko Akimoto ◽  
Yang-Fan Sheng ◽  
...  
Keyword(s):  
Land Surface ◽  
Urban Areas ◽  
Urban Canopy ◽  
Anthropogenic Heat ◽  
Surface Model ◽  
Urban Canopy Model ◽  
Simulation Performance ◽  
The Impact ◽  
Canopy Model ◽  
Northern Taiwan

Abstract. This study evaluates the impact of urbanization over northern Taiwan using the Weather Research and Forecasting (WRF) Model coupled with the Noah land-surface model and a modified urban canopy model (WRF–UCM2D). In the original UCM coupled to WRF (WRF–UCM), when the land use in the model grid is identified as "urban", the urban fraction value is fixed. Similarly, the UCM assumes the distribution of anthropogenic heat (AH) to be constant. This may not only lead to over- or underestimation of urban fraction and AH in urban and non-urban areas, but spatial variation also affects the model-estimated temperature. To overcome the abovementioned limitations and to improve the performance of the original UCM model, WRF–UCM is modified to consider the 2-D urban fraction and AH (WRF–UCM2D).The two models were found to have comparable temperature simulation performance for urban areas, but large differences in simulated results were observed for non-urban areas, especially at nighttime. WRF–UCM2D yielded a higher correlation coefficient (R2) than WRF–UCM (0.72 vs. 0.48, respectively), while bias and RMSE achieved by WRF–UCM2D were both significantly smaller than those attained by WRF–UCM (0.27 and 1.27 vs. 1.12 and 1.89, respectively). In other words, the improved model not only enhanced correlation but also reduced bias and RMSE for the nighttime data of non-urban areas. WRF–UCM2D performed much better than WRF–UCM at non-urban stations with a low urban fraction during nighttime. The improved simulation performance of WRF–UCM2D in non-urban areas is attributed to the energy exchange which enables efficient turbulence mixing at a low urban fraction. The result of this study has a crucial implication for assessing the impacts of urbanization on air quality and regional climate.

scholarly journals Incorporating an Urban Irrigation Module into the Noah Land Surface Model Coupled with an Urban Canopy Model

2014 ◽  
Vol 15 (4) ◽  
pp. 1440-1456 ◽  
Author(s):  
Pouya Vahmani ◽  
Terri S. Hogue
Keyword(s):  
Water Use ◽  
Land Surface ◽  
Land Surface Model ◽  
Urban Canopy ◽  
Surface Model ◽  
Urban Canopy Model ◽  
Irrigation Scheme ◽  
Modeling Framework ◽  
Noah Land Surface Model ◽  
Canopy Model

Abstract The current research examines the influence of irrigation on urban hydrological cycles through the development of an irrigation scheme within the Noah land surface model (LSM)–Single Layer Urban Canopy Model (SLUCM) system. The model is run at a 30-m resolution for a 2-yr period over a 49 km2 urban domain in the Los Angeles metropolitan area. A sensitivity analysis indicates significant sensitivity relative to both the amount and timing of irrigation on diurnal and monthly energy budgets, hydrological fluxes, and state variables. Monthly residential water use data and three estimates of outdoor water consumption are used to calibrate the developed irrigation scheme. Model performance is evaluated using a previously developed MODIS–Landsat evapotranspiration (ET) and Landsat land surface temperature (LST) products as well as hourly ET observations through the California Irrigation Management Information System (CIMIS). Results show that the Noah LSM–SLUCM realistically simulates the diurnal and seasonal variations of ET when the irrigation module is incorporated. However, without irrigation, the model produces large biases in ET simulations. The ET errors for the nonirrigation simulations are −56 and −90 mm month−1 for July 2003 and 2004, respectively, while these values decline to −6 and −11 mm month−1 over the same 2 months when the proposed irrigation scheme is adopted. Results show that the irrigation-induced increase in latent heat flux leads to a decrease in LST of about 2°C in urban parks. The developed modeling framework can be utilized for a number of applications, ranging from outdoor water use estimation to climate change impact assessments.

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