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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

2012; The Meteorological Society of Japan; Volume: 90B; Linguagem: Inglês

10.2151/jmsj.2012-b03

2186-9057

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

Climate variability and models

The present study applies the WRF model involving the single-layer urban canopy model (hereafter, WRF_UCM) to urban climate simulation of the Tokyo metropolitan area for August (2004-2007) and compare results to (a) observations, and (b) the WRF model involving the slab urban model (hereafter, WRF_SLAB). In this urban area, WRF_UCM accurately captures the observed monthly mean daytime and nocturnal UHI, whereas WRF_SLAB does not show a nocturnal UHI. Moreover, the observed diurnal variations of the surface air temperature for central Tokyo and Kumagaya, a nearby inland city, are reproduced well by WRF_UCM. However, WRF_SLAB exhibits both a 1-hr phase shift and a 6.2°C excess oscillation magnitude over observations. In addition, WRF_UCM accurately reproduces the frequency distribution of surface air temperatures, showing a maximum at 27°C, whereas WRF_SLAB produce a bimodal distribution, with double peaks at 23 and 33°C. Finally, WRF_UCM does a much better job than WRF_SLAB at modeling the relative humidity.