Modeling

Large Eddy Simulation (LES) Model

 LES is a numerical modeling approach that explicitly calculates large eddies having larger than the grid size, while the effects of small eddies are taken into account by a subgrid turbulence model.

In the meteorological field, this approach has been used to examine the turbulence structure of the atmospheric boundary layer, to perform studies of physical processes, and to develop a parameterization scheme for an ensemble mean turbulent model.

 We have been developed two local meteorological models based on the LES model; the developed models are parallelized with the message-passing interface (MPI). One model is based on a generalized curvilinear coordinate system to describe steep terrain(Δx~100m); the other model can resolve urban buildings(Δx~10m). We plan to use our LES model to examine convective thermal structure, to analyze the urban thermal environment in detail, and to analyze basin fog.

(Ryosaku IKEDA)

The templeture simulation result of the developing City-LES model around TOKYO Station.
The conceptual graph of Raidosity The heat environmental mitigation effect graph of street trees (surface templeture)
Papers
  • Ikeda,R., Kusaka, H., Iizuka, S.,Boku, T.,Akimoto,Y.,Development of Parallelized Urban Meteorological Model,587-589,(Acknowledgement: RECCA) PDF.
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Urban Canopy Model (UCM)

 To determine the mechanism of urban heat island formation, numerical simulations are an active area research. There are three main models for describing the urban thermal environment on a mesoscale: 1) the slab model, 2) the single-layer urban canopy model, and 3) the multi-layer urban canopy model.

 e have developed the single-layer and multi-layer urban canopy models, which have the following features: (a) considering the influence of street canyons, which are parameterized to represent the urban geometry; (b) accounting for building shadows and radiation reflection; and (c) estimating both the surface temperatures of, and fluxes from, roads and buildings.

 In the multi-layer UCM, a building drag term is included in the momentum equations. We plan to analyze the urban climate by using our urban canopy model.

The conceptual graph of Monolayer Urban Canopy Model 1 The conceptual graph of Monolayer Urban Canopy Model 2(Calculation of shadow and sunny place)
The comparative result of simulation value (calculated by model) and observation value


(Doan Quang Van)

Papers
  • Lin, C., C. Su, H. Kusaka, Y. Akimoto, Y. Sheng, J. Huang, and H. Hsu 2016: Impact of an improved WRF urban canopy model on diurnal air temperature simulation over northern Taiwan. Atmospheric Chemistry and Physics, 16, 1809–1822. DOI: :10.5194/acp-16-1809-2016, 2016/02/16 .
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  • Ikeda, R., Kusaka, H., 2010: Proposing the simplification of the multilayer urban canopy model: Intercomparison study of four models. J. Appl. Meteor. Clim., 49, 902-919. 2010/05/01 (Acknowledgement: S5) .
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  • Kusaka, H., 2008: Modeling efforts and future challenges of urban climate research. Tenki, 55, 227-240. 2008/04/01(Acknowledgement: S5) .
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  • Kusaka, H., Kimura, F., 2004: Thermal effects of urban canyon structure on the nocturnal heat island. J. Appl. Meteor., 43, 1899-1910. 2004/12/01 (Citations:48times) .
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  • Kusaka, H., Kimura, F., 2004: Coupling single-layer urban canopy model with a simple atmospheric model : Impact on urban heat island simulation for an idealized case. J. Meteor. Soc. Japan, 82, 67-80. 2004/02/25 (Citations:47times) .
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  • Kusaka, H., Kondo, H., Kikegawa, Y., Kimura, F., 2001: A simple single-layer urban canopy model for atmospheric models : Comparison with multi-layer and slab models. Bound. -Layer Meteor., 101, 329-358. 2001/11/01 (Citations:137times) .
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  • Kusaka, H., Chen, F., Tewari, M., Dudhia, J., Gill, D.O., Duda, M. G., Wang, W., Miya, Y., 2012: 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. J. Meteor. Soc. Japan., 90B, 33-45. (Acknowledgement: S5, T2K) .
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Local Meteorological Model (LMM)

  Understanding local wind circulation, for instance, land/sea breezes and fall wind, is important.
  Such understanding can be achieved not only through experimental observations but also through numerical simulations.
  So, the local meteorological models can contribute the studies on local weather.
  In our laboratory, local meteorological models have been developed.
  Students several types of the physics schemes and coupled these to our own atmospheric model.
(Takayuki KATO)

Weather Research and Forecasting (WRF) Model

 Coming soon
 
(Akifumi NISHI)

Papers
  • Doan, Q.V., and H. Kusaka, 2016: Numerical study on regional climate change due to the rapid urbanization of greater Ho Chi Minh City's metropolitan area over the past 20 years, International Journal of Climatology, 36(10), 3633–3650, DOI: 10.1002/joc.4582,2016/08/01 (Acknowledgments: CCS) .
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  • Doan, Q., H. Kusaka and Q.B. Ho, 2016: Impact of future urbanization on temperature and thermal comfort index in a developing tropical city: Ho Chi Minh City, Urban Climate, 17, 20-31, DOI: :10.1016/j.uclim.2016.04.003, 2016/06/08 (Acknowledgments: CCS) .
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  • Kusaka, H., 2011: Application and problem of the regional climate model WRF to urban climatology research.Journal of Geography, 120(2), 285-295. 2011/05/20(Acknowledgement: S8) .
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  • Kusaka, H., Takata, T., Takane, Y., 2010: Reproducibility of regional climate in central Japan using the 4-km resolution WRF model. SOLA, 6, 113-116. 2010/09/04 (Acknowledgement: S5) .
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  • Akimoto, Y., Kusaka, H., 2010: Sensitivity of the WRF regional meteorological model to input datasets and surface parameters for the Kanto plain on fine summer days. Geophysical Review of Japan., 83, 324-340. 2010/05/01 (Acknowledgement: S5) .
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  • Kusaka, H., 2009: On the regional Climate model WRF. Nagare, 28, 3-12. 2009/02/01(Acknowledgement: S5) .
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  • Kusaka, H., Crook, A., Knievel, J., Dudhia, J., 2005: Sensitivity of WRF model to advection and diffusion schemes on simulation of heavy rainfall event along the Baiu front. SOLA, 1, 177-180. 2005/12/03 .
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  • Kusaka, H., Crook, A., Dudhja, J., Wada, K., 2005: Comparison of the WRF and MM5 models for simulation of heavy rainfall along the Baiu front. SOLA, 1, 197-200. 2005/10/01 .
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  • Kusaka, H., Chen, F., Tewari, M., Dudhia, J., Gill, D.O., Duda, M. G., Wang, W., Miya, Y., 2012: 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. J. Meteor. Soc. Japan., 90B, 33-45. (Acknowledgement: S5, T2K) .
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  • Kusaka, H., Hara, M., Takane, Y., 2012: Urban climate projection by the WRF model at 3-km horizontal grid incremet: Dynamical downscaling and predicting heat stress in the 2070’s August for Tokyo, Osaka, and Nagoya metropolies. J. Meteor. Soc. Japan., 90B, 47-64. (Acknowledgement: S5) .
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