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Research on Urban Meteorology and Climatology

urban meteorological atmospheric model
Fig. An example of surface air temperature distribution on a typical summer night (05/AUG/2005 21JST) simulated by the non-hydrostatic mesoscale model, JMA-NHM. Left: coupled with newly developed urban canopy scheme, center: without the urban canopy scheme, right: differentials of the two cases.

Recently, the heat island phenomenon has generated significant discussion in Japan. On a heat contour map, the phenomenon appears as an island-like area of higher temperatures above urban surfaces than over surrounding rural ones. It is more marked in larger urban areas including Tokyo, Osaka and Nagoya. In such mega-cities, the number of heat stroke cases rises with higher daily maximum temperatures, and residents increasingly experience restless nights at temperatures of over 25℃. The heat island phenomenon is also considered to be linked with urban ozone formation and heavy rainfall in urban areas. However, the actual conditions and mechanisms behind such meteorological phenomena in urban areas remain unclear. Urban atmospheric conditions exhibit highly complex and varied facades reflecting the complicated meteorological variables of clouds/precipitation formation and complex land surface configurations (topography, urban style/scale and so on). As a result, there is demand for a sophisticated numerical atmospheric model that can be used to reproduce or forecast the characteristics of these complicated urban atmospheric conditions in order to clarify how urban surface development affects the atmosphere above. We are currently developing an urban meteorological atmospheric model incorporating the urban canopy concept, which enables the expression of urban morphology surface conditions in its land surface parameterization. The image above shows an example of reproduction for nighttime surface air temperatures in the Tokyo metropolitan area using the urban model. Comparison of temperature distribution between the results with (left) and without (center) urban canopy parameterization indicates that areas excessively warmed by urban surfaces seem to be reproduced accurately.


Job title Name
HeadAkihiko Murata
Senior Researcher Akira YAMAMOTO

last update : Apr. 4 2018
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