Study of the spatial structure of urban heat island in regional central cities by laser radar

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Recently, a chain of cumulus (called Kanpachi Gumo) frequently appears over the Kanpachi Street in Tokyo. From the case studies of the temperature and wind distributions in relation to the cloud chain in 1989, it is concluded as follows:1) The cloud chain appeared, when Japan Islands were covered with the Pacific high.2) The south-southewest sea breeze from Sagami Bay and the south-southeast sea breeze from Tokyo Bay formed a local convergence area along the Kanpachi Street during the daytime. Consequently, an ascending air current occurred around Kanpachi Street.3) A remarkable heat island was formed around Kanpachi Street during the day time. As a result, the convection was reinforced by the heat island circulation.The observation of the cloud chain over the Kanpachi Street was carried out by using low-level radio sound, pilot balloon, etc. during the summer in 1992. The main results are summarized as follows:4) The height of the cloud top was about 15000 m, and was about 500 m higher than that of the previous study.5) In the daytime, the convergence are of sea breezes from the Tokyo Bay and from the Sagami Bay existed over the Kanpachi Street.6) In the afternoon, high temperature zone was observed along the Kanpachi Street.In the present study, a portable laser radar for meteorological measurements in atmospheric boundary layer and troposphere has been developed. We succeeded to obrained vertical distribution of aerosols to show the structure of the urban heat island.