Chemical transport model on-line coupled with RAMS for regional chemical climate

Fast growing East Asian countries with their rapid increase in population and economy and, consequently, with their augmented energy consumption and production, show a dramatic increase of the emissions of air pollutants like sulfur and nitrogen oxides and particulates. As a consequence, acid deposition and long range transboundary air pollution are becoming one of the major concerns of Environmental Protection Agencies in each country which have recently started to expand their monitoring activities. Oceans such as the East China Sea, the Japan Sea between mainland China and Japan, as well as the Pacific Ocean cover a huge fraction of the region, and the interaction between Pacific maritime air masses and continental air masses strongly affect the meteorology and climatology of East Asia. In particular, as a result of this interaction, storm tracks and orographic precipitation during winter, synoptic scale persistent precipitation belt related to the summer monsoon, and the passage of fast moving typhoon represent some of the climate features characteristic of this region (Emori et al., 2000). Therefore knowledge of both pollutant concentration and meteorological parameters over these oceans is critically necessary to understand the long-range transport and transformation processes. However there are quite few observation point over these oceans, therefore remote sensing observation (i.e., satellite) and/or simulations with a regional meteorological model become important tools to evaluate the spatial distribution of cloud and precipitation in this area. To overcome these difficulties, an on-line regional scale chemical transport model fully coupled with CSU-RAMS (Regional Atmospheric Modeling System, Pielke et al., 1992) was developed to study regional transboundary air pollution. In particular, the coupled model can be adopted to simulate regional meteorological climate and chemical composition climate over the Asian and West Pacific region. This study shows the role of meteorological and climatological conditions in the transboundary air pollution transport in East Asia and indicates the climatological changes of chemical composition concentration and deposition by season.