Modeling study of severe ozone pollution during the summer of 2010 in Tokyo metropolitan area

Abstract

To examine the mechanism of the severe O₃ pollution, a numerical simulation analysis based on WRF/CMAQ was applied during the period from 20th to 25th July 2010, when the photochemical smog warnings had been issued all over that Tokyo Metropolitan Area. It was suggested that the high concentrations of O₃ that appeared around the inland area in the Kanto region were caused by the retention of precursors (NO₂ and VOCs) around a sea-breeze front. On the other hand, it was found from the model simulation of the high concentrations that appeared surrounding the coastal area of Tokyo Bay were caused by the transportation of O₃ passed over the sea surface from the western part of Japan toward the coastal area of Tokyo Bay. Though the model showed a reasonable agreement with the diurnal variation of the observed concentrations, the model generally underestimated the daily maximum of the observed O₃. In order to understand the main factor of the underestimation, it should to be required to confirm the model performance of the vertical distribution and the sea surface concentration of O₃ as well as the horizontal distribution.