To understand the photochemical smog behavior in the Kanto area, a field aircraft investigation was conducted from August 9 to 12, 1978. During the four days of experiment ten runs using a twin-engine Cessna 402 and an Alouette III helicopter were made to measure pollutant and meteorological parameter profiles. It was found that there is a relationship between the pollutant concentration and the local weather partterns in particular, the sea-land breeze.
August 9th was a typical of the sea-land breeze day causing high photochemical smog inland over the Kanto plain. In the morning, the sea breeze front was formed near the shore, gradually moving inland. The concentration patterns show two peak regions with the sea breeze front as the dividing line.
The topography shows that there are three different sea breezes in the Kanto region. There is a smallscale sea breeze from Tokyo Bay which usually penetrates into the center of Tokyo earliest as a SE wind. The second is a large-scale sea breeze blowing from Sagami Bay, designated as a South wind, which arrives at the center of Tokyo later than the Tokyo Bay sea breeze. The third is another large-scale sea breeze from the sea of Kashima designated as an East wind. Depending upon the general wind direction, these three sea breezes create a very complicated wind pattern over the Kanto Plain.
On August 12, 1978 there was high photochemical smog in Kanagawa Prefecture caused by just such a complex wind structure. The easterly wind replaced the morning land breeze (notherly wind) during the afternoon. This resulted in a low concentration O3 zone where the clean easterly wind had penetrated into the northern Kanto region. In the south of this clean zone, the high O3 concentration zone stretched from Tokyo to Yokohama area.
