The spatial and temporal variation of cloud is important to understand the concept of local climate such as prediction of torrential rainfall. There is an obvious contrast in land use between the urban and rural area along the Shigenobu River in the Matsuyama plain. Thus, the purpose of this study is to investigate the effects of differences in land use on the cloud formation. For this purpose, we analyzed the observations data of solar radiation, surface heat flux, air temperature and humidity. Here, clear sky rate was considered as an index to identify the reduction in the solar radiation due to presence of clouds. We observed that, solar radiation over urban area tends to be smaller than that over the rural area in the afternoon on days with a sunshine percentage from 50% to 80%. This was demonstrated by the development of mixing layer estimated from surface heat flux. In urban area the development of the cloud were observed even after the mixing layer reached the lifted condensation level whereas no such significant changes were observed in rural area. The obtained result would be beneficial for the study of the rainfall pattern in urban watersheds and to understand the effects of urbanization on the local climate.


Clear sky rate, solar radiation, land use, surface heat flux, lifted condensation level, mixing layer

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