Abstract
The appearance of a high concentration area of the photochemical oxidant (Ox) over the Kanto Plain was evaluated in terms of the sea breeze system. The sea breeze days, in a which southerly wind developed in the southern Kanto Plain, were selected during July–August of 1990–2011. A principal component analysis was used to explain the distribution of the daily maximum Ox concentration. The sea breeze days were classified as Type 1 and Type 2, wherein the area of the high Ox concentration developed in the northern and southern regions, respectively. The inland penetration of the sea breeze from Sagami Bay and Tokyo Bay of the Type 1 occurred earlier than that of Type 2. The easterly wind suggested to have originated from Kashimanada developed in the northeast region of Type 2. The high Ox concentration area was located in front of the sea breeze front that was supplied with Ox by the upper air in both types. The Ox advection was negative when the sea breeze front passed. The time of the daily maximum inland Ox concentration tended to be later than that in the southern region for both types. These results indicated that the daily maximum Ox concentration is influenced by the speed of the inland penetration of the sea breeze.
