Kajino Z
Fig. 8. Scatter diagrams of daily precipitation pH at NC stations, (x-axis) observed and (y-axis) calculated using (a) observed chemical compositions (blue), (b) with 90% of the components derived from sea salt excluded (green), and (c) with 99 % of the components derived from sea salt excluded (pink). Suto et al. (2010) estimated that depositional mass fluxes of sea salt particles of whole size ranges (coarse mode plus LSPs) decreased by one order of magnitude at distances of several kilometers from Tokyo Bay and by two orders of magnitude at distances of several tens of kilometers from the coast. Nevertheless, it is not possible to explain the discrepancy because the current model configuration is not appropriate to simulate it: the horizontal grid resolution is too coarse to resolve the NC stations, and the sea salt emission in the surf zone is not considered. However, because the salinity of precipitation is much lower than that of sea water (approximately three orders of magnitude, estimated from the averages of Table 2), the pH of the diluted seawater becomes almost 7 and, thus, should not affect the pH of precipitation substantially. Regression analysis of anthropogenic sulfur oxides showed similar results for nss-SO2" aerosols, and W-nss-SO2" in precipitation, while a somewhat lower R was obtained for SO2 gas (Fig. 7a). The Sim:Obs ratio was greater for SO2 than it was for the other two phases (Fig. 7b). In addition to uncertainty in SO2 emission amount, overestimation of SO2 is likely due to underestimation of dry deposition velocities or underestimation of the oxidation rate from S(IV) to S(VI).
Kajino et al. (2012) showed that the modeled size distributions, such as PM2.5/ PM10 of total mass and PM1/bulk ratios of chemical components, were consistent with the observations. To simulate processes in the evolution of aerosol mi-croscale properties such as chemical composition, size distribution, and mixing state, we developed a new triple-moment aerosol dynamics model (Kajino, 2011a, b; Kajino and Kondo, 2011; Kajino et al., 2012). RAQM2 enables non-equilibrium calculations of gas-to-particle mass transfers over a wide range of aerosol particle diameters, from 1nm to supermicron particles. We formulated oxidation of SO2 in the gas phase and in the aqueous phase of cloud, rain, and aerosol water droplets (Kajino et al., 2012). SO2 oxidation can also occur as a heterogeneous oxidation on dust particle surfaces (Tang et al., 2004), casino z mobile but we did not implement this pathway in the model. The SO2 molecule is oxidized by the OH radical in the air to form H2SO4 gas. Because the vapor pressure of H2SO4 gas is extremely low, homogeneous nucleation and condensation onto pre-existing particles occur simultaneously. Imlay, P. Kirk, J. Lim, R. R. McNeil, W. Metcalf, C. P. Cheng, J. Li, Y. K. Li, Z. P. Mao, Y. T. Xu, Y. C. Zhu, A. Abashian, K. Gotow, E. H. Low, M. E. Mattson, F. Naito, L. Piilonen, K. L. Sterner, S. Lusin, C. Rosenfeld, A. Wang, S. Wilson, M. Frautschi, H. Kagan, R. Kass, C. G. Trahern, Winston Ko, R. L. Lander, K. Maeshima, R. L. Malchow, J. R. Smith, K. Sparks, M. C.S.
Wang, Z., Xie, F., Sakurai, T., Han, Z., Carmichael, G.R., Streets, D., Engardt, M., Holloway, T., Hayami, H., Kajino, M. et al. R., SAKURAI T., STREETS D., HOZUMI Y., UEDA H., PARK S.U., FUNG C., HAN Z., KAJINO M., ENGARDT M., BENNET C., HAYAMI H., SARTELET K., HOLLOWAY T., WANG Z., KANNARI A., FU J., MATSUDA M., THONGBOONCHOO N., AMANN M. The Model Intercomparison Study for Asia Phase II, Methodology and Overview of Findings. Yamaji, K., Ohara, T., Uno, I., Tanimoto, H., Kurokawa, J. I., and Akimoto, H.: Analysis of the seasonal variation of ozone in the boundary layer in east Asia using the community multi-scale air quality model: what controls surface ozone levels over Japan?
