17:15 〜 18:45
[AAS09-P12] Quantification of aerosol wet deposition and washout contribution using a meteorology-chemistry model
キーワード：エアロゾル、湿性沈着、気象化学モデル
Aerosols affect the radiative properties of clouds by changing cloud particle number concentrations (Twomey, 1977) and cloud lifetime by changing cloud particle size (Albrecht, 1989). This aerosol-cloud interaction is highly complex and is the most significant factor of uncertainty in global warming projections (IPCC AR6, 2021). Therefore, it is important to accurately estimate the amounts of aerosols in the atmosphere. This study aims to quantify the “wet deposition processes” that most influence the atmospheric aerosol volume.
In this study, we used Offline Scale-Chem (Nakata et al., 2021), an offline coupled meteorology model (Nishizawa et al., 2015; Sato et al., 2015) and chemical transport model (Kajino et al., 2019; Kajino et al., 2021). The initial and boundary conditions were obtained from MANL and the calculation period was from 00UTC on Oct. 1st to 00UTC on Nov. 1st, 2019. The analysis of the contribution of the washout (below-cloud scavenging) process to the change in the average of PM2.5 concentrations showed that the amount of change in PM2.5 concentrations was -0.65 μg/m3 (-21.8%), quantitatively indicating that the washout process contributed to the reduction of PM2.5 concentrations. The average contribution of washout process to total wet deposition was 63.91% for sulfate and 67.60% for nitrate. We conducted sensitivity experiments with changing washout efficiency (HYSPLIT, 2014; Draxler, 1997) (0x/1x(CTL)/10x) and calculated aerosol scavenging rate (Feng and Wang, 2012; Olszowski, 2016; Fujino and Miyamoto, 2022) for each rainfall events. As the washout efficiency increased, the aerosol scavenging rate also increased. We could be quantified the amount of change in the scavenging rate in response to change in washout efficiency. The present results suggest that the wet deposition processes are effective in reducing PM2.5 concentration.
In this study, we used Offline Scale-Chem (Nakata et al., 2021), an offline coupled meteorology model (Nishizawa et al., 2015; Sato et al., 2015) and chemical transport model (Kajino et al., 2019; Kajino et al., 2021). The initial and boundary conditions were obtained from MANL and the calculation period was from 00UTC on Oct. 1st to 00UTC on Nov. 1st, 2019. The analysis of the contribution of the washout (below-cloud scavenging) process to the change in the average of PM2.5 concentrations showed that the amount of change in PM2.5 concentrations was -0.65 μg/m3 (-21.8%), quantitatively indicating that the washout process contributed to the reduction of PM2.5 concentrations. The average contribution of washout process to total wet deposition was 63.91% for sulfate and 67.60% for nitrate. We conducted sensitivity experiments with changing washout efficiency (HYSPLIT, 2014; Draxler, 1997) (0x/1x(CTL)/10x) and calculated aerosol scavenging rate (Feng and Wang, 2012; Olszowski, 2016; Fujino and Miyamoto, 2022) for each rainfall events. As the washout efficiency increased, the aerosol scavenging rate also increased. We could be quantified the amount of change in the scavenging rate in response to change in washout efficiency. The present results suggest that the wet deposition processes are effective in reducing PM2.5 concentration.