Comparison of three aerosol representations of NHM-Chem (v1.0) for the simulations of air quality and climate-relevant variables

Abstract

Abstract. This study provides comparisons of aerosol representation methods incorporated into a regional-scale nonhydrostatic meteorology-chemistry model (NHM-Chem). Three options for aerosol representations are currently available: the 5-category nonequilibrium (Aitken, soot-free accumulation, soot-containing accumulation, dust, and sea salt), 3-category nonequilibrium (Aitken, accumulation, and coarse), and bulk equilibrium (submicron, dust, and sea salt) methods. The 3-category method is widely used in three-dimensional air quality models. The 5-category method, the standard method of NHM-Chem, is an extensional development of the 3-category method and provides improved predictions of regional climate by implementing separate treatments of light absorber and ice nuclei, namely, soot and dust, from the accumulation and coarse mode categories. The bulk equilibrium method was also developed for operational air quality forecasting with simple aerosol dynamics representations. The total CPU times of the 5-category and 3-category methods were 91 % and 44 % greater than that of the bulk method, respectively. The bulk equilibrium method was shown to be eligible for operational forecast purposes, namely, the surface mass concentrations of air pollutants such as O3, mineral dust, and PM2.5. The simulated surface concentrations and depositions of bulk chemical species of the 3-category method were not significantly different from those of the 5-category method. However, the internal mixture assumption of soot/soot-free and dust/sea salt particles in the 3-category method resulted in significant differences in the size distribution and hygroscopicity of the particles. The unrealistic dust/sea salt complete mixture of the 3-category method induced significant errors in the prediction of the mineral dust-containing CCN, which alters heterogeneous ice nucleation in cold rain processes. The overestimation of soot hygroscopicity by the 3-category method induced errors in the BC-containing CCN, BC deposition, and light-absorbing AOT (AAOT). Nevertheless, the difference in AAOT was less pronounced with the 3-category method because the overestimation of the absorption enhancement was compensated by the overestimation of hygroscopic growth and the consequent loss due to in-cloud scavenging. In terms of total properties, such as aerosol optical thickness (AOT) and cloud condensation nuclei (CCN), the results of the 3-category method were acceptable. To evaluate the significance of separate soot and dust treatments in the 5-category method in terms of aerosol-cloud-radiation interaction processes, online simulation with a chemistry-to-meteorology feedback process is required.

A study on the impact of mountainous terrain on transboundary and local pollution

“…In this study, a regional chemical transport model [5,6] was implemented in the Scalable Computing for Advanced Library and Environment (SCALE) meteorological model [7,8]. The chemical transport model consists of advection, turbulent diffusion, gas-phase photochemistry, SOA chemistry, liquid-phase chemistry, heterogeneous chemical reactions, and aerosol microphysical processes.…”

Effects of Mountains on Aerosols Determined by AERONET/DRAGON/J‐ALPS Measurements and Regional Model Simulations

“…In this study, a regional chemical transport model simulation was conducted to investigate the effects of terrain on aerosols. A chemical transport model (Kajino et al, 2019(Kajino et al, , 2021 was implemented in the Scalable Computing for Advanced Library and Environment (SCALE) meteorological model (Nishizawa et al, 2015;Sato et al, 2015). The chemical transport model consists of advection, turbulent diffusion, gas-phase photochemistry, SOA chemistry, liquid-phase chemistry, heterogeneous chemical reactions, and aerosol microphysical processes.…”

“…We used the monthly Global Fire Emissions Database (Giglio et al, 2010) for open biomass burning emissions and the Model of Emissions of Gases and Aerosols from Nature (Guenther et al, 2006) for biogenic emissions. Hourly volcanic SO 2 emissions in Japan developed by Kajino et al (2021) were used. For the nesting boundary condition, we used the 3-D concentration over the Asian region calculated by NHM-Chem with the same model domain (covering East Asia with 30 km grid resolutions) and the same emission inventories as Kajino et al (2019).…”

Statistical Evaluation of the Temperature Forecast Error in the Lower‐Level Troposphere on Short‐Range Timescales Induced by Aerosol Variability

“…Simulations of atmospheric aerosols typically involve various elemental processes, such as primary emission of aerosols and precursor gases, chemical reactions and secondary formation, transportation, dry and wet deposition processes, and aerosol‐atmosphere interaction processes. Thus, numerous aerosol simulation studies have been conducted with regional (e.g., Grell et al., 2005; Kajino et al., 2019, 2021a) and global (Bhattacharjee et al., 2018; Gong et al., 2012; Morcrette et al., 2009; Rémy et al., 2019; Tanaka et al., 2003 Tanaka & Chiba, 2005) models. Regardless of these numerous studies, high uncertainties are associated with each elemental process.…”

“…Regardless of these numerous studies, high uncertainties are associated with each elemental process. To reduce these uncertainties, several approaches have been studied, such as data assimilation to improve the spatiotemporal distribution (Benedetti et al., 2009; Kajino et al., 2021a; Sekiyama et al., 2010; Yumimoto et al., 2016), the inversion method to improve emissions (Maki et al., 2011; Sugimoto et al., 2010; Yumimoto et al., 2008), and the superensemble method (Kajino et al., 2021b). However, because the solution to all these processes requires very high computational resources, aerosols have been treated in a simple manner in numerical weather prediction (NWP) models.…”