Numerical Simulation of Urban Heat Island Effect by the WRF Model with 4-km Grid Increment: An Inter-Comparison Study between the Urban Canopy Model and Slab Model

Kusaka, Hiroyuki; Chen, Fei; Tewari, Mukul; Dudhia, Jimy; Gill, David; Duda, Michael; Wang, Wei; Miya, Yukako

doi:10.2151/jmsj.2012-b03

Cited by 85 publications

(49 citation statements)

References 50 publications

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“…The nighttime temperatures at other urban sites such as Madrid 1/Madrid 2, Milan 1/Milan 2, and Paris Orly are generally underpredicted due to a poor representation of urban canopy and urban heat island in the default treatments of WRF. Using WRF coupled with a single-layer urban canopy model (UCM) for energy and momentum exchange between the urban surface and the atmosphere, several studies showed large improvement in simulated near-surface air temperature and relative humidity during nighttime (e.g., Chen et al, 2004;Shrestha et al, 2009;Kusaka et al, 2012;Kim et al, 2012). This is because the UCM can provide a more realistic energy balance of the urban region, via parameterizations of street canyons, building wall/roof, road surfaces, and anthropogenic heating.…”

Section: Simulations Over D01 At a Horizontal Grid Resolution Of 05 •mentioning

confidence: 99%

Application of WRF/Chem-MADRID and WRF/Polyphemus in Europe – Part 1: Model description, evaluation of meteorological predictions, and aerosol–meteorology interactions

Zhang

Sartelet

Wu³

et al. 2013

Atmos. Chem. Phys.

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Abstract. Comprehensive model evaluation and comparison of two 3-D air quality modeling systems (i.e., the Weather Research and Forecast model (WRF)/Polyphemus and WRF with chemistry and the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID) (WRF/Chem-MADRID)) are conducted over Western Europe. Part 1 describes the background information for the model comparison and simulation design, the application of WRF for January and July 2001 over triple-nested domains in Western Europe at three horizontal grid resolutions: 0.5°, 0.125°, and 0.025°, and the effect of aerosol/meteorology interactions on meteorological predictions. Nine simulated meteorological variables (i.e., downward shortwave and longwave radiation fluxes (SWDOWN and LWDOWN), outgoing longwave radiation flux (OLR), temperature at 2 m (T2), specific humidity at 2 m (Q2), relative humidity at 2 m (RH2), wind speed at 10 m (WS10), wind direction at 10 m (WD10), and precipitation (Precip)) are evaluated using available observations in terms of spatial distribution, domainwide daily and site-specific hourly variations, and domainwide performance statistics. The vertical profiles of temperature, dew points, and wind speed/direction are also evaluated using sounding data. WRF demonstrates its capability in capturing diurnal/seasonal variations and spatial gradients and vertical profiles of major meteorological variables. While the domainwide performance of LWDOWN, OLR, T2, Q2, and RH2 at all three grid resolutions is satisfactory overall, large positive or negative biases occur in SWDOWN, WS10, and Precip even at 0.125° or 0.025° in both months and in WD10 in January. In addition, discrepancies between simulations and observations exist in T2, Q2, WS10, and Precip at mountain/high altitude sites and large urban center sites in both months, in particular, during snow events or thunderstorms. These results indicate the model's difficulty in capturing meteorological variables in complex terrain and subgrid-scale meteorological phenomena, due to inaccuracies in model initialization parameterization (e.g., lack of soil temperature and moisture nudging), limitations in the physical parameterizations (e.g., shortwave radiation, cloud microphysics, cumulus parameterizations, and ice nucleation treatments) as well as limitations in surface heat and moisture budget parameterizations (e.g., snow-related processes, subgrid-scale surface roughness elements, and urban canopy/heat island treatments and CO2 domes). While the use of finer grid resolutions of 0.125° and 0.025° shows some improvements for WS10, WD10, Precip, and some mesoscale events (e.g., strong forced convection and heavy precipitation), it does not significantly improve the overall statistical performance for all meteorological variables except for Precip. The WRF/Chem simulations with and without aerosols show that aerosols lead to reduced net shortwave radiation fluxes, 2 m temperature, 10 m wind speed, planetary boundary layer (PBL) height, and precipitation and increase aerosol optical depth, cloud condensation nuclei, cloud optical depth, and cloud droplet number concentrations over most of the domain. These results indicate a need to further improve the model representations of the above parameterizations as well as aerosol–meteorology interactions at all scales.

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Section: Simulations Over D01 At a Horizontal Grid Resolution Of 05 •mentioning

confidence: 99%

Application of WRF/Chem-MADRID and WRF/Polyphemus in Europe – Part 1: Model description, evaluation of meteorological predictions, and aerosol–meteorology interactions

Zhang

Sartelet

Wu³

et al. 2013

Atmos. Chem. Phys.

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“…Dynamical downscaling for current-urban climate and its verification 2.1 Design of the numerical experiment Although the WRF model has been used for numerical weather predictions, few studies (i.e., Miao et al 2009, Chen et al 2010, Kusaka et al 2012 have applied it to a multi-year urban climate simulation with a coupled UCM. Therefore, we first evaluate the modeling system against current observations before applying it to future climate prediction.…”

Section: Introductionmentioning

confidence: 99%

Urban Climate Projection by the WRF Model at 3-km Horizontal Grid Increment: Dynamical Downscaling and Predicting Heat Stress in the 2070’s August for Tokyo, Osaka, and Nagoya Metropolises

Kusaka

Hara

Takane

2012

Journal of the Meteorological Society of Japan

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139

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This study presents the projected urban climate for the 2070s' August in the three largest urban areas, Tokyo, Osaka, and Nagoya in Japan. To accurately evaluate the urban climate, the simulations use the Weather Research and Forecast (WRF) model with 3-km grid increment coupled to an urban canopy model (UCM). To project future urban climate, the simulations apply dynamical downscaling to three GCMs (MIROC3.2-medres, MRI-CGCM2.3.2a, CSIRO-Mk3.0) and use the ensemble average for results. The results provide estimates of the heat stress to future residents of Tokyo, Osaka, and Nagoya.The WRF-UCM model reproduces the observed spatial distribution of the surface air temperature in the 2000s' August, giving an all-domain mean bias of À1.2 C and RSME of 2.7 C. For Tokyo, Nagoya, and Osaka, these biases are À0.6, À0.1, and À0.4 C. Moreover, the diurnal temperature variations at these urban stations are well reproduced. The projected monthly average August temperatures in the 2070s are about 2.3 C higher than those in the 2000s at the three urban areas and comparable to those in the record-breaking hot summer of 2010. (Predictions by individual ensemble members di¤er by 0.8-1.2 C.) As a result, urban areas will experience uncomfortable sleeping nights nearly every day in August, with roughly as many heat-induced sleeping-discomfort nights as those in 2010. Moreover, application of the wet-bulb globe temperature (WBGT) shows that people in Tokyo will be warned not to strenuously exercise outdoors for 62% of the daytime hours in the 2070s, a sharp increase from the 30% of the 2000s. (Predictions by individual ensemble members range from 54-67%). Osaka and Nagoya will have even more restrictions on outdoor exercise. Finally, the urban heat island intensity is 1.5 C in Tokyo of the 2070s, comparable to the background climate warming of 2.3 C.

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“…Also, Kikegawa et al (2011) suggested an AT increase of 0.9 °C at an office district due to additional anthropogenic heat from a comparison between weekday and weekend observations of AT. On the other hand, urban canopy effects in the WRF were analyzed in detail by Kusaka et al (2012). They broadly compared ATs between urban canopy and slab surface conditions on the Kanto Plain in Japan.…”

Section: Model Validationsmentioning

confidence: 99%

Numerical Simulations of Summer Mesoscale Heat-Stress around the Seto Inland Sea, Japan

Ohashi

Shimada

Ohsawa

2014

Journal of the Meteorological Society of Japan

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We simulated mesoscale distributions of summertime human heat stress around the Seto Inland Sea in western Japan, using a mesoscale numerical model: WRF-ARW at 2 km horizontal resolution. In this study, the Heat Index, which indicates the real human-felt temperature, was adopted as a heat-hazard index that can represent mesoscale spatial distributions of human heat stress. Our simulations specified regions of undesirably high daytime Heat Index around the Seto Inland Sea for the year 2007, an extremely hot summer. Although the daytime high surface air temperature in the Osaka Plain was the most prominent of the calculation domain (at 1400 JST, August air temperature means of 33-35 °C), high Heat Index regions were broadly found in other land areas around the Seto Inland Sea in addition to the Osaka Plain: the Tokushima, Okayama, Sanuki, and Nakatsu Plains (at 1400 JST, August Heat Index means of 37-39 °C). Daytime differences between air temperature and Heat Index were large in the four previously mentioned plains (excluding the Osaka Plain), showing a difference of 5-7 °C in our simulation. The large differences were caused by the difference of relative humidity in the region. Hence, residents in these plains should carefully avoid high heat stress, because they may be feel hotter than the actual air temperature.To discuss mechanisms increasing the mesoscale Heat Index, sensitivity experiments for mountains and sea surface temperature were conducted. They revealed that those factors worked selectively in the above regions. The existence of mountains induced thermal effects due to a valley-like terrain, and higher sea surface temperature produced warm and moist air transports from the sea. Daytime local circulations, which were topographically and thermally driven, were important for both factors. These mountain and high sea surface temperature influences produced increases of Heat Index of 1-2 °C in the aforementioned four regions.

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Numerical Simulation of Urban Heat Island Effect by the WRF Model with 4-km Grid Increment: An Inter-Comparison Study between the Urban Canopy Model and Slab Model

Cited by 85 publications

References 50 publications

Application of WRF/Chem-MADRID and WRF/Polyphemus in Europe – Part 1: Model description, evaluation of meteorological predictions, and aerosol–meteorology interactions

Application of WRF/Chem-MADRID and WRF/Polyphemus in Europe – Part 1: Model description, evaluation of meteorological predictions, and aerosol–meteorology interactions

Urban Climate Projection by the WRF Model at 3-km Horizontal Grid Increment: Dynamical Downscaling and Predicting Heat Stress in the 2070’s August for Tokyo, Osaka, and Nagoya Metropolises

Numerical Simulations of Summer Mesoscale Heat-Stress around the Seto Inland Sea, Japan

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