抄録
In recent years much attention has been paid on urban local climate such as heat island phenomenon and severe rainfall. Urban heat island is known as a phenomenon where urban temperature is higher than rural temperature. Whereas investigation for urban heat island phenomenon has been reported in many cities (e. g., Sakakibara et al., 1996), the investigation of water vapor distribution is still poor. Spatial and temporal distribution of water vapor is as important as air temperature, because local severe rainfall is caused by convergence of water vapor. On the basis of field measurements in Matsuyama plain, we found that urban absolute humidity is lower than rural absolute humidity. Following the manner of urban heat island phenomenon, we call the phenomenon 'urban dry island phenomenon'. The object of this study is to analyze the feature and cause of urban dry island phenomenon.
