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

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.

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NHM-Chem, the Japan MeteorologicalAgency's regional meteorology – chemistry model (v1.0): model description and aerosol representations

10.5194/gmd-2018-128 ◽

2018 ◽

Cited By ~ 9

Author(s):

Mizuo Kajino ◽

Makoto Deushi ◽

Tsuyoshi Thomas Sekiyama ◽

Naga Oshima ◽

Keiya Yumimoto ◽

...

Keyword(s):

Air Quality ◽

Mineral Dust ◽

Cloud Condensation Nuclei ◽

Regional Scale ◽

Sea Salt ◽

Absorption Enhancement ◽

Model Description ◽

Hygroscopic Growth ◽

Mass Concentrations ◽

Non Equilibrium

Abstract. A regional-scale meteorology – chemistry model (NHM-Chem v1.0) has been developed. Three options for aerosol representations are currently available: the 5-category non-equilibrium (Aitken, soot-free accumulation, accumulation internally mixed with soot, dust, and sea-salt), 3-category non-equilibrium (Aitken, accumulation, and coarse), and bulk equilibrium (submicron, dust, and sea-salt) methods. These three methods are suitable for the predictions of regional climate, air quality, and operational forecasts, respectively. 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 3-category method was shown to be eligible for air quality simulations, namely, mass concentrations and depositions. 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. Even though the 3-category method was not designed to simulate aerosol-cloud-radiation interaction processes, its performance in terms of bulk properties, such as aerosol optical thickness (AOT) and cloud condensation nuclei (CCN), was acceptable. However, some specific parameters exhibited significant differences or systematic errors. The unrealistic dust/sea-salt complete mixture of the 3-category method induced significant errors in the prediction of mineral dust containing CCN. The overestimation of soot hygroscopicity by the 3-category method induced errors in BC-containing CCN, BC deposition, and absorbing AOT (AAOT). The difference in AAOT was less pronounced because the overestimation of the absorption enhancement was compensated by the overestimation of hygroscopic growth and the consequent loss due to in-cloud scavenging.

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

Geoscientific Model Development ◽

10.5194/gmd-14-2235-2021 ◽

2021 ◽

Vol 14 (4) ◽

pp. 2235-2264

Author(s):

Mizuo Kajino ◽

Makoto Deushi ◽

Tsuyoshi Thomas Sekiyama ◽

Naga Oshima ◽

Keiya Yumimoto ◽

...

Keyword(s):

Air Quality ◽

Optical Thickness ◽

Mineral Dust ◽

Cloud Condensation Nuclei ◽

Regional Scale ◽

Sea Salt ◽

Aerosol Optical Thickness ◽

Absorption Enhancement ◽

Equilibrium Method ◽

Non Equilibrium

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 five-category non-equilibrium (Aitken, soot-free accumulation, soot-containing accumulation, dust, and sea salt), three-category non-equilibrium (Aitken, accumulation, and coarse), and bulk equilibrium (submicron, dust, and sea salt) methods. The three-category method is widely used in three-dimensional air quality models. The five-category method, the standard method of NHM-Chem, is an extensional development of the three-category method and provides improved predictions of variables relating to aerosol–cloud–radiation interaction processes by implementing separate treatments of light absorber and ice nuclei particles, namely, soot and dust, from the accumulation- and coarse-mode categories (implementation of aerosol feedback processes to NHM-Chem is still ongoing, though). The bulk equilibrium method was developed for operational air quality forecasting with simple aerosol dynamics representations. The total CPU times of the five-category and three-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 three-category method were not significantly different from those of the five-category method. However, the internal mixture assumption of soot/soot-free and dust/sea salt particles in the three-category method resulted in significant differences in the size distribution and hygroscopicity of the particles. The unrealistic dust/sea salt complete mixture of the three-category method induced significant errors in the prediction of the mineral dust-containing cloud condensation nuclei (CCN), which alters heterogeneous ice nucleation in cold rain processes. The overestimation of soot hygroscopicity by the three-category method induced errors in the BC-containing CCN, BC deposition, and light-absorbing aerosol optical thickness (AAOT). Nevertheless, the difference in AAOT was less pronounced with the three-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 CCN, the results of the three-category method were acceptable.

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ModelE2-TOMAS development and evaluation using aerosol optical depths, mass and number concentrations

Geoscientific Model Development Discussions ◽

10.5194/gmdd-7-5831-2014 ◽

2014 ◽

Vol 7 (5) ◽

pp. 5831-5918 ◽

Cited By ~ 2

Author(s):

Y. H. Lee ◽

P. J. Adams ◽

D. T. Shindell

Keyword(s):

Organic Matter ◽

General Circulation ◽

Mineral Dust ◽

Cloud Condensation Nuclei ◽

Circulation Model ◽

Convective Transport ◽

Sea Salt ◽

Computationally Efficient ◽

Anthropogenic Aerosol ◽

Aerosol Model

Abstract. The TwO-Moment Aerosol Sectional microphysics model (TOMAS) has been integrated into the state-of-the-art general circulation model, GISS ModelE2. TOMAS has the flexibility to select a size resolution as well as the lower size cutoff. A computationally efficient version of TOMAS is used here, which has 15 size bins covering 3 nm to 10 μm aerosol dry diameter. For each bin, it simulates the total aerosol number concentration and mass concentrations of sulphate, pure elementary carbon (hydrophobic), mixed elemental carbon (hydrophilic), hydrophobic organic matter, hydrophilic organic matter, sea salt, mineral dust, ammonium, and aerosol-associated water. This paper provides a detailed description of the ModelE2-TOMAS model and evaluates the model against various observations including aerosol precursor gas concentrations, aerosol mass and number concentrations, and aerosol optical depths. Additionally, global budgets in ModelE2-TOMAS are compared with those of other global aerosol models, and the TOMAS model is compared to the default aerosol model in ModelE2, which is a bulk aerosol model. Overall, the ModelE2-TOMAS predictions are within the range of other global aerosol model predictions, and the model has a reasonable agreement with observations of sulphur species and other aerosol components as well as aerosol optical depth. However, ModelE2-TOMAS (as well as the bulk aerosol model) cannot capture the observed vertical distribution of sulphur dioxide over the Pacific Ocean possibly due to overly strong convective transport. The TOMAS model successfully captures observed aerosol number concentrations and cloud condensation nuclei concentrations. Anthropogenic aerosol burdens in the bulk aerosol model running in the same host model as TOMAS (ModelE2) differ by a few percent to a factor of 2 regionally, mainly due to differences in aerosol processes including deposition, cloud processing, and emission parameterizations. Larger differences are found for naturally emitted aerosols such as sea salt and mineral dust. With TOMAS, ModelE2 has three different aerosol models (the bulk aerosol model and modal-based aerosol microphysics model, MATRIX) and allows exploration of the uncertainties associated with aerosol modelling within the same host model, NASA GISS ModelE2.

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An integrated modeling study on the effects of mineral dust and sea salt particles on clouds and precipitation

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-23959-2010 ◽

2010 ◽

Vol 10 (10) ◽

pp. 23959-24014 ◽

Cited By ~ 1

Author(s):

S. Solomos ◽

G. Kallos ◽

J. Kushta ◽

M. Astitha ◽

C. Tremback ◽

...

Keyword(s):

Air Quality ◽

Mineral Dust ◽

Eastern Mediterranean ◽

Atmospheric Modeling ◽

Sea Salt ◽

Cloud Formation ◽

Dust Particles ◽

Limited Area ◽

Aerosol Cloud ◽

Climate Interactions

Abstract. The amount of airborne particles that will nucleate and form cloud droplets under specific atmospheric conditions, depends on their number concentration, size distribution and chemical composition. Aerosol is affected by primary particle emissions, gas-phase precursors, their transformation and interaction with atmospheric constituents, clouds and dynamics. A comprehensive assessment of these interactions requires an integrated approach; most studies however decouple aerosol processes from cloud and atmospheric dynamics and cannot account for all the feedbacks involved in aerosol-cloud-climate interactions. This study addresses aerosol-cloud-climate interactions with the Integrated Community Limited Area Modeling System (ICLAMS) that includes online parameterization of the physical and chemical processes between air quality and meteorology. ICLAMS is an extended version of the Regional Atmospheric Modeling System (RAMS) and it has been designed for coupled air quality – meteorology studies. Model sensitivity tests for a single-cloud study as well as for a case study over the Eastern Mediterranean illustrate the importance of aerosol properties in cloud formation and precipitation. Mineral dust particles are often coated with soluble material such as sea-salt, thus exhibiting increased CCN efficiency. Increasing the percentage of salt-coated dust particles by 15% in the model resulted in more vigorous convection and more intense updrafts. The clouds that were formed extended about 3 km higher and the initiation of precipitation was delayed by one hour. Including on-line parameterization of the aerosol effects improved the model bias for the twenty-four hour accumulated precipitation by 7%. However, the spatial distribution and the amounts of precipitation varied greatly between the different aerosol scenarios. These results indicate the large portion of uncertainty that remains unresolved and the need for more accurate description of aerosol feedbacks in atmospheric models and climate change predictions.

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A comprehensive study of hygroscopic properties of calcium- and magnesium-containing salts: implication for hygroscopicity of mineral dust and sea salt aerosols

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-2115-2019 ◽

2019 ◽

Vol 19 (4) ◽

pp. 2115-2133 ◽

Cited By ~ 14

Author(s):

Liya Guo ◽

Wenjun Gu ◽

Chao Peng ◽

Weigang Wang ◽

Yong Jie Li ◽

...

Keyword(s):

Growth Factors ◽

Physicochemical Properties ◽

Mineral Dust ◽

Aerosol Particles ◽

Sea Salt ◽

Hygroscopic Growth ◽

Continuous Growth ◽

Sea Salt Aerosols ◽

Hygroscopic Properties ◽

Calcium And Magnesium

Abstract. Calcium- and magnesium-containing salts are important components for mineral dust and sea salt aerosols, but their physicochemical properties are not well understood yet. In this study, hygroscopic properties of eight Ca- and Mg-containing salts, including Ca(NO3)2⚫4H2O, Mg(NO3)2⚫6H2O, MgCl2⚫6H2O, CaCl2⚫6H2O, Ca(HCOO)2, Mg(HCOO)2⚫2H2O, Ca(CH3COO)2⚫H2O and Mg(CH3COO)2⚫4H2O, were investigated using two complementary techniques. A vapor sorption analyzer was used to measure the change of sample mass with relative humidity (RH) under isotherm conditions, and the deliquescence relative humidities (DRHs) for temperature in the range of 5–30 ∘C as well as water-to-solute ratios as a function of RH at 5 and 25 ∘C were reported for these eight compounds. DRH values showed large variation for these compounds; for example, at 25 ∘C DRHs were measured to be ∼ 28.5 % for CaCl2⚫6H2O and >95 % for Ca(HCOO)2 and Mg(HCOO)2⚫2H2O. We further found that the dependence of DRH on temperature can be approximated by the Clausius–Clapeyron equation. In addition, a humidity tandem differential mobility analyzer was used to measure the change in mobility diameter with RH (up to 90 %) at room temperature, in order to determine hygroscopic growth factors of aerosol particles generated by atomizing water solutions of these eight compounds. All the aerosol particles studied in this work, very likely to be amorphous under dry conditions, started to grow at very low RH (as low as 10 %) and showed continuous growth with RH. Hygroscopic growth factors at 90 % RH were found to range from 1.26 ± 0.04 for Ca(HCOO)2 to 1.79 ± 0.03 for Ca(NO3)2, and the single hygroscopicity parameter ranged from 0.09–0.13 for Ca(CH3COO)2 to 0.49–0.56 for Ca(NO3)2. Overall, our work provides a comprehensive investigation of hygroscopic properties of these Ca- and Mg-containing salts, largely improving our knowledge of the physicochemical properties of mineral dust and sea salt aerosols.

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Expected Impacts of Mixing European Beech with Silver Fir on Regional Air Quality and Radiation Balance

Climate ◽

10.3390/cli8100105 ◽

2020 ◽

Vol 8 (10) ◽

pp. 105

Author(s):

Boris Bonn ◽

Jürgen Kreuzwieser ◽

Ruth-Kristina Magh ◽

Heinz Rennenberg ◽

Dirk Schindler ◽

...

Keyword(s):

Air Quality ◽

Tree Species ◽

Cloud Condensation Nuclei ◽

Regional Scale ◽

Abies Alba ◽

European Beech ◽

Radiation Balance ◽

Silver Fir ◽

Radiative Balance ◽

Air Chemistry

The anticipated climate change during the next decades is posing crucial challenges to ecosystems. In order to decrease the vulnerability of forests, introducing tree species’ mixtures are a viable strategy, with deep-rooting native Silver fir (Abies alba) being a primary candidate for admixture into current pure stands of European beech (Fagus sylvatica) especially in mountainous areas. Such a change in forest structure also has effects on the regional scale, which, however, have been seldomly quantified. Therefore, we measured and modeled radiative balance and air chemistry impacts of admixing Silver fir to European beech stands, including changes in biogenic volatile organic compound emissions. An increased fraction of Silver fir caused a smaller albedo and a (simulated) larger evapotranspiration, leading to a dryer and warmer forest. While isoprene emission was negligible for both species, sesquiterpene and monoterpene emissions were larger for fir than for beech. From these differences, we derived that ozone concentration as well as secondary organic aerosols and cloud condensation nuclei would increase regionally. Overall, we demonstrated that even a relatively mild scenario of tree species change will alter the energy balance and air quality in a way that could potentially influence the climate on a landscape scale.

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Properties of cloud condensation nuclei (CCN) in the trade wind marine boundary layer of the western North Atlantic

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-2675-2016 ◽

2016 ◽

Vol 16 (4) ◽

pp. 2675-2688 ◽

Cited By ~ 21

Author(s):

Thomas B. Kristensen ◽

Thomas Müller ◽

Konrad Kandler ◽

Nathalie Benker ◽

Markus Hartmann ◽

...

Keyword(s):

Boundary Layer ◽

Long Range ◽

North Atlantic ◽

Particle Number ◽

Marine Boundary Layer ◽

Mineral Dust ◽

Cloud Condensation Nuclei ◽

Sea Salt ◽

Condensation Nuclei ◽

Accumulation Mode

Abstract. Cloud optical properties in the trade winds over the eastern Caribbean Sea have been shown to be sensitive to cloud condensation nuclei (CCN) concentrations. The objective of the current study was to investigate the CCN properties in the marine boundary layer (MBL) in the tropical western North Atlantic, in order to assess the respective roles of inorganic sulfate, organic species, long-range transported mineral dust and sea-salt particles. Measurements were carried out in June–July 2013, on the east coast of Barbados, and included CCN number concentrations, particle number size distributions and offline analysis of sampled particulate matter (PM) and sampled accumulation mode particles for an investigation of composition and mixing state with transmission electron microscopy (TEM) in combination with energy-dispersive X-ray spectroscopy (EDX). During most of the campaign, significant mass concentrations of long-range transported mineral dust was present in the PM, and influence from local island sources can be ruled out. The CCN and particle number concentrations were similar to what can be expected in pristine marine environments. The hygroscopicity parameter κ was inferred, and values in the range 0.2–0.5 were found during most of the campaign, with similar values for the Aitken and the accumulation mode. The accumulation mode particles studied with TEM were dominated by non-refractory material, and concentrations of mineral dust, sea salt and soot were too small to influence the CCN properties. It is highly likely that the CCN were dominated by a mixture of sulfate species and organic compounds.

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Development of an aerosol chemical transport model RAQM2 and predictions of Northeast Asian aerosol mass, size, chemistry, and mixing type

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-13405-2012 ◽

2012 ◽

Vol 12 (5) ◽

pp. 13405-13456 ◽

Cited By ~ 4

Author(s):

M. Kajino ◽

Y. Inomata ◽

K. Sato ◽

H. Ueda ◽

Z. Han ◽

...

Keyword(s):

Air Quality ◽

Transport Model ◽

Regional Scale ◽

Chemical Transport ◽

Sea Salt ◽

Chemical Components ◽

Air Quality Model ◽

Chemical Transport Model ◽

Wide Range ◽

Northeast Asian

Abstract. A new aerosol chemical transport model, Regional Air Quality Model 2 (RAQM2), was developed to simulate Asian air quality. We implemented a simple version of a modal-moment aerosol dynamics model (MADMS) and achieved a completely dynamic (non-equilibrium) solution of a gas-to-particle mass transfer over a wide range of aerosol diameters from 1 nm to super μm. To consider a variety of atmospheric aerosol properties, a category approach was utilized, in which the aerosols were distributed into 4 categories: Aitken mode (ATK), soot-free accumulation mode (ACM), soot aggregates (AGR), and coarse mode (COR). Condensation, evaporation, and Brownian coagulations for each category were solved dynamically. A regional-scale simulation (Δ x = 60 km) was performed for the entire year of 2006 covering the Northeast Asian region. Statistical analyses showed that the model reproduced the regional-scale transport and transformation of the major inorganic anthropogenic and natural air constituents within factors of 2 to 5. The modeled PM1/bulk ratios of the chemical components were consistent with the observations, indicating that the simulations of aerosol mixing types were successful. Non-sea salt SO42- mixed with ATK + ACM was the largest at Hedo in summer, whereas it mixed with AGR was substantial in cold seasons. Ninety-eight percent of the modeled NO3- was mixed with sea salt at Hedo, whereas 53.7% of the NO3- was mixed with sea salt at Gosan, located upwind toward the Asian continent. The condensation of HNO3 onto sea salt particles during transport over the ocean makes the difference in the NO3- mixing type at the two sites. Because the aerosol mixing type alters optical properties and cloud condensation nuclei activity, its accurate prediction and evaluation are indispensable for aerosol-cloud-radiation interaction studies.

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Properties of cloud condensation nuclei (CCN) in the trade wind marine boundary layer of the Eastern Caribbean Sea

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-30757-2015 ◽

2015 ◽

Vol 15 (21) ◽

pp. 30757-30791

Author(s):

T. B. Kristensen ◽

T. Müller ◽

K. Kandler ◽

N. Benker ◽

M. Hartmann ◽

...

Keyword(s):

Boundary Layer ◽

Long Range ◽

Particle Number ◽

Marine Boundary Layer ◽

Mineral Dust ◽

Cloud Condensation Nuclei ◽

Caribbean Sea ◽

Sea Salt ◽

Accumulation Mode ◽

Eastern Caribbean

Abstract. Cloud optical properties in the trade winds over the Eastern Caribbean Sea have been shown to be sensitive to cloud condensation nuclei (CCN) concentrations. The objective of the current study was to investigate the CCN properties in the marine boundary layer (MBL) in the Eastern Caribbean, in order to assess the respective roles of organic species, long-range transported mineral dust, and sea salt particles. Measurements were carried out in June–July 2013, on the East Coast of Barbados and included CCN number concentrations, particle number size distributions, as well as off-line analysis of sampled particulate matter (PM) and sampled accumulation mode particles for an investigation of composition and mixing state with transmission electron microscopy (TEM) in combination with energy-dispersive X-ray spectroscopy (EDX). During most of the campaign, significant mass concentrations of long-range transported mineral dust was present in the PM, and influence from local island sources can be ruled out. The CCN and particle number concentrations were similar to what can be expected in pristine marine environments. The hygroscopicity parameter κ was inferred, and values in the range 0.2–0.5 were found during most of the campaign, with similar values for the Aitken and the accumulation mode. The accumulation mode particles studied with TEM were dominated by non-refractory material, and concentrations of mineral dust, sea salt, and soot were too small to influence the CCN properties. It is highly likely that the CCN were dominated by a mixture of sulphate species and organic compounds.

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Development of the RAQM2 aerosol chemical transport model and predictions of the Northeast Asian aerosol mass, size, chemistry, and mixing type

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-11833-2012 ◽

2012 ◽

Vol 12 (24) ◽

pp. 11833-11856 ◽

Cited By ~ 43

Author(s):

M. Kajino ◽

Y. Inomata ◽

K. Sato ◽

H. Ueda ◽

Z. Han ◽

...

Keyword(s):

Air Quality ◽

Transport Model ◽

Regional Scale ◽

Chemical Transport ◽

Sea Salt ◽

Aerosol Size Distribution ◽

Chemical Components ◽

Chemical Transport Model ◽

Wide Range ◽

Northeast Asian

Abstract. A new aerosol chemical transport model, the Regional Air Quality Model 2 (RAQM2), was developed to simulate the Asian air quality. We implemented a simple version of a triple-moment modal aerosol dynamics model (MADMS) and achieved a completely dynamic (non-equilibrium) solution of a gas-to-particle mass transfer over a wide range of aerosol diameters from 1 nm to super-μm. To consider a variety of atmospheric aerosol properties, a category approach was utilized in which the aerosols were distributed into four categories: particles in the Aitken mode (ATK), soot-free particles in the accumulation mode (ACM), soot aggregates (AGR), and particles in the coarse mode (COR). The aerosol size distribution in each category is characterized by a single mode. The condensation, evaporation, and Brownian coagulations for each mode were solved dynamically. A regional-scale simulation (Δx = 60 km) was performed for the entire year of 2006 covering the Northeast Asian region. The modeled PM1/bulk ratios of the chemical components were consistent with observations, indicating that the simulated aerosol mixing types were consistent with those in nature. The non–sea-salt SO42− mixed with ATK + ACM was the largest at Hedo in summer, whereas the SOSO42− was substantially mixed with AGR in the cold seasons. Ninety-eight percent of the modeled NO3− was mixed with sea salt at Hedo, whereas 53.7% of the NO3− was mixed with sea salt at Gosan, which is located upwind toward the Asian continent. The condensation of HNO3 onto sea salt particles during transport over the ocean accounts for the difference in the NO3− mixing type at the two sites. Because the aerosol mixing type alters the optical properties and cloud condensation nuclei activity, its accurate prediction and evaluation are indispensable for aerosol-cloud-radiation interaction studies.

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