The Regional Integrated Environmental Model System （RIEMS 2.0） coupled with a chemistry-aerosol model and the Princeton Ocean Model （POM） is employed to simulate regional oceanic impact on atmospheric circulation and the direct radiative effect （DRE） of aerosol over East Asia. The aerosols considered in this study include both major anthropogenic aerosols （e.g., sulfate, black carbon, and organic carbon） and natural aerosols （e.g., soil dust and sea salt）. The RIEMS 2.0 is driven by NCEP/NCAR reanalysis II, and the simulated period is from 1 January to 31 December 2006. The results show the following： （1） The simulated annual mean sea-level pressure by RIEMS 2.0 with POM is lower than without POM over the mainland and higher without POM over the ocean. （2） In summer, the subtropical high simulated by RIEMS 2.0 with POM is stronger and extends further westward, and the continental low is stronger than without POM in summer. （3） The aerosol optical depth （AOD） simulated by RIEMS 2.0 with POM is larger in the middle and lower reaches of the Yangtze River than without POM. （4） The direct radiative effect with POM is stronger than that without POM in the middle and lower reaches of the Yangtze River and parts of southern China. Therefore, the authors should take account of the impact of the regional ocean model on studying the direct climate effect ＆aerosols in long term simulation.
The Regional Integrated Environmental Model System （RIEMS 2.0） with NCEP Reanalysis II is utilized to simulate the severe freezing rain and snow storm event over southern China in January 2008, which caused severe damage in the region. The relationships between the freezing rain process and the large-scale cir- culation, in terms of the westerly and low-level jets, water vapor transportation, and northerly wind area/intensity indices, were analyzed to tmderstand the mechanisms of the freezing rain occurrence. The results indicate the fol- lowing： （1） RIEMS 2.0 reproduced the pattern of precipi- tation in January 2008 well, especially for the temporal evolution of daily precipitation averaged over the Yangtze River valley and southern China; （2） RIEMS 2.0 repro- duced the persistent trough in the South Branch of the westerlies, of which the southwesterly currents trans- ported abundant moisture into southern China; （3） RIEMS 2.0 reasonably reproduced the pattern of frequencies of light and moderate rain, although it overestimated the frequency of rain in southern China. This study shows that RIEMS 2.0 can be feasibly applied to study extreme weather and climate events in East Asia.
