Air Pollution in the Surface Layer Accompanying a Local Front at the Onset of the Land Breeze

Abstract

A statistical study is made on the air pollution in the surface layer associated with a front-like phenomenon which propagates eastward in the central part of the Kanto plain at the transition from the sea breeze to the land breeze. It is shown that on winter days with westerly land breeze the passage of the front is followed by maxima of concentration of pollutants which are the constituents of vehicle exhaust. On the other hand, pollution is found to be less remarkable on winter days with northerly land breeze and on summer days. On the basis of statistical analysis and conjecture, it is considered that the pollution intensity is related to stability of the surface layer and emission rate in the land breeze layer, and that advection by the land breeze contributes to the transport of pollutant. Relations between these controlling factors and local meteorological conditions are examined.