Observed Structure of a Land Breeze Head in the Tokyo Metropolitan Area

Abstract

The penetration of a land breeze front and its turbulence structure was observed at the center of the Tokyo metropolitan area on 27?28 January 1983. A turbulence sonde, small tethersonde and an acoustic sounder were used for the experiment. The detailed shape of the land breeze head and its flow characteristics were analyzed. The penetration of the land breeze was detected at about 2130 JST, and the advance speed of the land breeze front was estimated to be about 2.4 m s?1. The shape of land breeze head was similar to that of a sea breeze head reported by Simpson et al. (1977). The top height of the land breeze head was 400 m and the depth of the land breeze layer proper was about 200 m. A closed circulation pattern was detected inside the land breeze head. Large velocity fluctuations were observed at the leading edge of the head and the boundary of the large turbulence zone showed a wavy pattern behind the land breeze head. These features coincided with the results of Simpson et al. (1977). A comparison of the advance velocity ratio of the land breeze front also showed good agreement with the laboratory experiment of Simpson and Britter (1980).