Study of relationship between daily maxima in ozone and temperature in an urban site in India

he relationship between surface-level observations of daily maxima in ozone (O3max) volume mixing ratio and ambient air temperature (Tmax) has been studied at an urban site, i.e. Pune (18.4°N, 73.8°E), India during 2003-04. The mixing ratios of O3max were found to be highest during winter to pre-monsoon period and lowest in the monsoon season. The dependence of O3max levels on Tmax has been quantified using the linear regression fit for the different seasons. However, except for the monsoon season, reasonably good correlations between O3max and Tmax were noticed. The correlation between daily O3max concentration and minimum NOx (NOxmin) concentration was also studied to assess the importance of photochemical mechanism mainly reduction in the loss due to titration. Overall, the strong dependencies of O3max on Tmax and NOxmin signify the role of both meteorological and photochemical processes during most months of a year. The positive slopes of ΔO3max/ΔTmax and ΔO3max/ΔNOxmin clearly indicate the role of significant production and accumulation of O3 under high temperature and low NOx conditions respectively, during winter and premonsoon seasons. The statistical analysis of O3 in relation with the key meteorological and chemical parameters is important to understand the sensitivity of secondary pollutants on various controlling factors

Environmental, Social and Governance (ESG) performance and sovereign bond spreads : an empirical analysis of OECD countries

What are the determinants of borrowing cost in international capital markets? Apart from macroeconomic fundamentals, are there any qualitative factors that might capture sovereign bond spreads? In this paper we consider to what extent Environmental, social and governance (ESG) performance can affect sovereign bond spreads. First, countries with good ESG performance tend to have less default risk and thus lower bond spreads. Moreover, the economic impact is stronger in the long-run, suggesting that ESG performance is a long-lasting phenomenon. Second, we examine the financial impact of separate ESG dimensions, and find that the environmental dimension appears to have no financial impact whereas governance weighs more than social factors. Third, we examine cross-countries differences and show that ESG performance has a more significant and stronger impact in the Eurozone than elsewhere in OECD countries. Fourth, we include evidence from the global financial crisis and find stronger influence of country sustainability performance during crisis period.Publisher PD

Calibration and measurement uncertainties of a continuous-flow cloud condensation nuclei counter (DMT-CCNC): CCN activation of ammonium sulfate and sodium chloride aerosol particles in theory and experiment

International audienceExperimental and theoretical uncertainties in the measurement of cloud condensation nuclei (CCN) with a continuous-flow thermal-gradient CCN counter from Droplet Measurement Technologies (DMT-CCNC) have been assessed by model calculations and calibration experiments with ammonium sulfate and sodium chloride aerosol particles in the diameter range of 20?220 nm. Experiments have been performed in the laboratory and during field measurement campaigns, extending over a period of more than one year and covering a wide range of operating conditions (650?1020 hPa ambient pressure, 0.5?1.0 L min?1 aerosol flow rate, 20?30°C inlet temperature, 4?34 K m?1 temperature gradient). For each set of conditions, the effective water vapor supersaturation (Seff) in the CCNC was determined from the measured CCN activation spectra and Köhler model calculations. High measurement precision was achieved under stable laboratory conditions, where relative variations of Seff in the CCNC were generally less than ±2%. During field measurements, however, the relative variability increased up to ±5?7%, which can be mostly attributed to variations of the CCNC column top temperature with ambient temperature. To assess the accuracy of the Köhler models used to calculate Seff, we have performed a comprehensive comparison and uncertainty analysis of the various Köhler models and thermodynamic parameterizations commonly used in CCN studies. For the relevant supersaturation range (0.05?2%), the relative deviations between different modeling approaches were as high as 25% for (NH4)2SO4 and 16% for NaCl. The deviations were mostly caused by the different parameterizations for the activity of water in aqueous solutions of (NH4)2SO4 and NaCl (activity parameterization, osmotic coefficient, and van't Hoff factor models). The uncertainties related to the model parameterizations of water activity clearly exceeded the CCNC measurement precision. Relative deviations caused by different ways of calculating or approximating solution density and surface tension did not exceed 3% for (NH4)2SO4 and 1.5% for NaCl. Nevertheless, they did exceed the CCNC measurement precision under well-defined operating conditions and should not be neglected in studies aimed at high accuracy. To ensure comparability of results, we suggest that CCN studies should always report exactly which Köhler model equations and parameterizations of solution properties were used. Substantial differences between the CCNC calibration results obtained with (NH4)2SO4 and NaCl aerosols under equal experimental conditions (relative deviations of Seff up to ~10%) indicate inconsistencies between widely used activity parameterizations derived from electrodynamic balance (EDB) single particle experiments (Tang and Munkelwitz, 1994; Tang, 1996) and hygroscopicity tandem differential mobility analyzer (HTDMA) aerosol experiments (Kreidenweis et al., 2005). Therefore, we see a need for further evaluation and experimental confirmation of preferred data sets and parameterizations for the activity of water in dilute aqueous (NH4)2SO4 and NaCl solutions. The experimental results were also used to test the CCNC flow model of Lance et al.~(2006), which describes the dependence of Seff on temperature, pressure, and flow rate in the CCN counter. This model could be applied after subtraction of a near-constant temperature offset and derivation of an instrument-specific thermal resistance parameter (RT?1.8 K W?1). At Seff>0.1% the relative deviations between the flow model and experimental results were mostly less than 5%, when the same Köhler model approach was used. At Seff?.1%, however, the deviations exceeded 20%, which can be attributed to non-idealities which also caused the near-constant temperature offset. Therefore, we suggest that the CCNC flow model can be used to extrapolate calibration results, but should generally be complemented by calibration experiments performed under the relevant operating conditions ? during field campaigns as well as in laboratory studies

Hygroscopicity distribution concept for measurement data analysis and modeling of aerosol particle mixing state with regard to hygroscopic growth and CCN activation

This paper presents a general concept and mathematical framework of particle hygroscopicity distribution for the analysis and modeling of aerosol hygroscopic growth and cloud condensation nucleus (CCN) activity. The cumulative distribution function of particle hygroscopicity, H(κ, Dd) is defined as the number fraction of particles with a given dry diameter, Dd, and with an effective hygroscopicity parameter smaller than the parameter κ. From hygroscopicity tandem differential mobility analyzer (HTDMA) and size-resolved CCN measurement data, H(κ, Dd) can be derived by solving the κ-Köhler model equation. Alternatively, H(κ, Dd) can be predicted from measurement or model data resolving the chemical composition of single particles. A range of model scenarios are used to explain and illustrate the concept, and exemplary practical applications are shown with HTDMA and CCN measurement data from polluted megacity and pristine rainforest air. Lognormal distribution functions are found to be suitable for approximately describing the hygroscopicity distributions of the investigated atmospheric aerosol samples. For detailed characterization of aerosol hygroscopicity distributions, including externally mixed particles of low hygroscopicity such as freshly emitted soot, we suggest that size-resolved CCN measurements with a wide range and high resolution of water vapor supersaturation and dry particle diameter should be combined with comprehensive HTDMA measurements and size-resolved or single-particle measurements of aerosol chemical composition, including refractory components. In field and laboratory experiments, hygroscopicity distribution data from HTDMA and CCN measurements can complement mixing state information from optical, chemical and volatility-based techniques. Moreover, we propose and intend to use hygros

Aerosols in the central Arctic cryosphere: satellite and model integrated insights during Arctic spring and summer

The central Arctic cryosphere is influenced by the Arctic amplification (AA) and is warming faster than the lower latitudes. AA affects the formation, loss, and transport of aerosols. Efforts to assess the underlying processes determining aerosol variability are currently limited due to the lack of ground-based and space-borne aerosol observations with high spatial coverage in this region. This study addresses the observational gap by making use of total aerosol optical depth (AOD) datasets retrieved by the AEROSNOW algorithm over the vast cryospheric region of the central Arctic during Arctic spring and summer. GEOS-Chem (GC) simulations combined with AEROSNOW-retrieved data are used to investigate the processes controlling aerosol loading and distribution at different temporal and spatial scales. For the first time, an integrated study of AOD over the Arctic cryosphere during sunlight conditions was possible with the AEROSNOW retrieval and GC simulations. The results show that the spatial patterns observed by AEROSNOW differ from those simulated by GC. During spring, which is characterized by long-range transport of anthropogenic aerosols in the Arctic, GC underestimates the AOD in the vicinity of Alaska in comparison with AEROSNOW retrieval. At the same time, it overestimates the AOD along the Bering Strait, northern Europe, and the Siberian central Arctic sea-ice regions, with differences of −12.3 % and 21.7 %, respectively. By contrast, GC consistently underestimates AOD compared with AEROSNOW in summer, when transport from lower latitudes is insignificant and local natural processes are the dominant source of aerosol, especially north of 70° N. This underestimation is particularly pronounced over the central Arctic sea-ice region, where it is −10.6 %. Conversely, GC tends to overestimate AOD along the Siberian and Greenland marginal sea-ice zones by 19.5 % but underestimates AOD along the Canadian Archipelago by −9.3 %. The differences in summer AOD between AEROSNOW data products and GC-simulated AOD highlight the need to integrate improved knowledge of the summer aerosol process into existing models in order to constrain its effects on cloud condensation nuclei, on ice nucleating particles, and on the radiation budget over the central Arctic sea ice during the developing AA period.</p

Cloud condensation nuclei in pristine tropical rainforest air of Amazonia: size-resolved measurements and modeling of atmospheric aerosol composition and CCN activity

Atmospheric aerosol particles serving as cloud condensation nuclei (CCN) are key elements of the hydrological cycle and climate. We have measured and characterized CCN at water vapor supersaturations in the range of <i>S</i>=0.10–0.82% in pristine tropical rainforest air during the AMAZE-08 campaign in central Amazonia. <br><br> The effective hygroscopicity parameters describing the influence of chemical composition on the CCN activity of aerosol particles varied in the range of &kappa;&asymp;0.1–0.4 (0.16&plusmn;0.06 arithmetic mean and standard deviation). The overall median value of &kappa;&asymp;0.15 was by a factor of two lower than the values typically observed for continental aerosols in other regions of the world. Aitken mode particles were less hygroscopic than accumulation mode particles (&kappa;&asymp;0.1 at <i>D</i>&asymp;50 nm; &kappa;&asymp;0.2 at <i>D</i>&asymp;200 nm), which is in agreement with earlier hygroscopicity tandem differential mobility analyzer (H-TDMA) studies. <br><br> The CCN measurement results are consistent with aerosol mass spectrometry (AMS) data, showing that the organic mass fraction (<i>f</i>_org) was on average as high as ~90% in the Aitken mode (<i>D</i>&le;100 nm) and decreased with increasing particle diameter in the accumulation mode (~80% at <i>D</i>&asymp;200 nm). The κ values exhibited a negative linear correlation with <i>f</i>_org (<i>R</i>²=0.81), and extrapolation yielded the following effective hygroscopicity parameters for organic and inorganic particle components: &kappa;_org&asymp;0.1 which can be regarded as the effective hygroscopicity of biogenic secondary organic aerosol (SOA) and &kappa;_inorg&asymp;0.6 which is characteristic for ammonium sulfate and related salts. Both the size dependence and the temporal variability of effective particle hygroscopicity could be parameterized as a function of AMS-based organic and inorganic mass fractions (&kappa;_p=&kappa;_org&times;<i>f</i>_org +&kappa;_inorg&times;<i>f</i>_inorg). The CCN number concentrations predicted with &kappa;_p were in fair agreement with the measurement results (~20% average deviation). The median CCN number concentrations at <i>S</i>=0.1–0.82% ranged from <i>N</i>_CCN,0.10&asymp;35 cm^&minus;3 to <i>N</i>_CCN,0.82&asymp;160 cm^&minus;3, the median concentration of aerosol particles larger than 30 nm was <i>N</i>_CN,30&asymp;200 cm^&minus;3, and the corresponding integral CCN efficiencies were in the range of <i>N</i>_CCN,0.10/<i>N</i>_CN,30&asymp;0.1 to <i>N</i>_CCN,0.82/<i>N</i>_CN,30&asymp;0.8. <br><br> Although the number concentrations and hygroscopicity parameters were much lower in pristine rainforest air, the integral CCN efficiencies observed were similar to those in highly polluted megacity air. Moreover, model calculations of <i>N</i>_CCN,<i>S</i> assuming an approximate global average value of &kappa;&asymp;0.3 for continental aerosols led to systematic overpredictions, but the average deviations exceeded ~50% only at low water vapor supersaturation (0.1%) and low particle number concentrations (&le;100 cm^&minus;3). Model calculations assuming a constant aerosol size distribution led to higher average deviations at all investigated levels of supersaturation: ~60% for the campaign average distribution and ~1600% for a generic remote continental size distribution. These findings confirm earlier studies suggesting that aerosol particle number and size are the major predictors for the variability of the CCN concentration in continental boundary layer air, followed by particle composition and hygroscopicity as relatively minor modulators. <br><br> Depending on the required and applicable level of detail, the information and parameterizations presented in this paper should enable efficient description of the CCN properties of pristine tropical rainforest aerosols of Amazonia in detailed process models as well as in large-scale atmospheric and climate models

Seasonal Variability in Fine Particulate Matter Water Content and Estimated pH over a Coastal Region in the Northeast Arabian Sea

The acidity of atmospheric particles can promote specific chemical processes that result in the production of extra condensed phases from lesser volatile species (secondary fine particulate matter), change the optical and water absorption characteristics of particles, and enhance trace metal solubility that can function as essential nutrients in nutrient-limited environments. In this study, we present an estimated pH of fine particulate matter (FPM) through a thermodynamic model and assess its temporal variability over a coastal location in the northeast Arabian Sea. Here, we have used the chemical composition of FPM (PM2.5) collected during the period between 2017–2019. Chemical composition data showed large variability in water-soluble ionic concentrations (WSIC; range: 2.3–39.9 μg m−3) with higher and lower average values during the winter and summer months, respectively. SO42− ions were predominant among anions, while NH4+ was a major contributor among cations throughout the season. The estimated pH of FPM from the forward and reverse modes exhibits a moderate correlation for winter and summer samples. The estimated pH of FPM is largely regulated by SO42− content and strongly depends on the relative ambient humidity, particularly in the forward mode. Major sources of FPM assessed based on Positive matrix factorization (PMF) and air-mass back trajectory analyses demonstrate the dominance of natural sources (sea salt and dust) during summer months, anthropogenic sources in winter months and mixed sources during the post-monsoon season

Cloud condensation nuclei in polluted air and biomass burning smoke near the mega-city Guangzhou, China – Part 2: Size-resolved aerosol chemical composition, diurnal cycles, and externally mixed weakly CCN-active soot particles

Size-resolved chemical composition, mixing state, and cloud condensation nucleus (CCN) activity of aerosol particles in polluted mega-city air and biomass burning smoke were measured during the PRIDE-PRD2006 campaign near Guangzhou, China, using an aerosol mass spectrometer (AMS), a volatility tandem differential mobility analyzer (VTDMA), and a continuous-flow CCN counter (DMT-CCNC). The size-dependence and temporal variations of the effective average hygroscopicity parameter for CCN-active particles (κa) could be parameterized as a function of organic and inorganic mass fractions (forg, finorg) determined by the AMS: κa,p=κorg·forg + κinorg·finorg. The characteristic κ values of organic and inorganic components were similar to those observed in other continental regions of the world: κorg≈0.1 and κinorg≈0.6. The campaign average κa values increased with particle size from ~0.25 at ~50 nm to ~0.4 at ~200 nm, while forg decreased with particle size. At ~50 nm, forg was on average 60% and increased to almost 100% during a biomass burning event. The VTDMA results and complementary aerosol optical data suggest that the large fractions of CCN-inactive particles observed at low supersaturations (up to 60% at S≤0.27%) were externally mixed weakly CCN-active soot particles with low volatility (diameter reduction <5% at 300 °C) and effective hygroscopicity parameters around κLV≈0.01. A proxy for the effective average hygroscopicity of the total ensemble of CCN-active particles including weakly CCN-active particles (κt) could be parameterized as a function of κa,p and the number fraction of low volatility particles determined by VTDMA (φLV): κt,p=κa,p−φLV·(κa,p−κLV). Based on κ values derived from AMS and VTDMA data, the observed CCN number concentrations (NCCN,S≈102–104 cm−3 at S = 0.068–0.47%) could be efficiently predicted from the measured particle number size distribution. The mean relative deviations between observed and predicted CCN concentrations were ~10% when using κt,p, and they increased to ~20% when using only κa,p. The mean relative deviations were not higher (~20%) when using an approximate continental average value of κ≈0.3, although the constant κ value cannot account for the observed temporal variations in particle composition and mixing state (diurnal cycles and biomass burning events). Overall, the results confirm that on a global and climate modeling scale an average value of κ≈0.3 can be used for approximate predictions of CCN number concentrations in continental boundary layer air when aerosol size distribution data are available without information about chemical composition. Bulk or size-resolved data on aerosol chemical composition enable improved CCN predictions resolving regional and temporal variations, but the composition data need to be highly accurate and complemented by information about particle mixing state to achieve high precision (relative deviations <20%)

Cloud condensation nuclei (CCN) from fresh and aged air pollution in the megacity region of Beijing

Atmospheric aerosol particles serving as cloud condensation nuclei (CCN) are key elements of the hydrological cycle and climate. CCN properties were measured and characterized during the CAREBeijing-2006 campaign at a regional site south of the megacity of Beijing, China. Size-resolved CCN efficiency spectra recorded for a supersaturation range of &lt;i&gt;S&lt;/i&gt;=0.07% to 0.86% yielded average activation diameters in the range of 190 nm to 45 nm. The corresponding effective hygroscopicity parameters (&amp;kappa;) exhibited a strong size dependence ranging from ~0.25 in the Aitken size range to ~0.45 in the accumulation size range. The campaign average value (&amp;kappa; =0.3 ± 0.1) was similar to the values observed and modeled for other populated continental regions. &lt;br&gt;&lt;br&gt; The hygroscopicity parameters derived from the CCN measurements were consistent with chemical composition data recorded by an aerosol mass spectrometer (AMS) and thermo-optical measurements of apparent elemental and organic carbon (EC and OC). The CCN hygroscopicity and its size dependence could be parameterized as a function of only AMS based organic and inorganic mass fractions (&lt;i&gt;f&lt;/i&gt;&lt;sub&gt;org&lt;/sub&gt;, &lt;i&gt;f&lt;/i&gt;&lt;sub&gt;inorg&lt;/sub&gt;) using the simple mixing rule &amp;kappa;&lt;sub&gt;p&lt;/sub&gt; ≈ 0.1 · &lt;i&gt;f&lt;/i&gt;&lt;sub&gt;org&lt;/sub&gt; + 0.7 · &lt;i&gt;f&lt;/i&gt;&lt;sub&gt;inorg&lt;/sub&gt;. &lt;br&gt;&lt;br&gt; When the measured air masses originated from the north and passed rapidly over the center of Beijing (fresh city pollution), the average particle hygroscopicity was reduced (&amp;kappa; = 0.2 ± 0.1), which is consistent with enhanced mass fractions of organic compounds (~50%) and EC (~30%) in the fine particulate matter (PM&lt;sub&gt;1&lt;/sub&gt;). Moreover, substantial fractions of externally mixed weakly CCN-active particles were observed at low supersaturation (&lt;i&gt;S&lt;/i&gt;=0.07%), which can be explained by the presence of freshly emitted soot particles with very low hygroscopicity (&amp;kappa; &lt; 0.1). Particles in stagnant air from the industrialized region south of Beijing (aged regional pollution) were on average larger and more hygroscopic, which is consistent with enhanced mass fractions (~60%) of soluble inorganic ions (mostly sulfate, ammonium, and nitrate). Accordingly, the number concentration of CCN in aged air from the megacity region was higher than in fresh city outflow ((2.5–9.9) × 10&lt;sup&gt;3&lt;/sup&gt; cm&lt;sup&gt;−3&lt;/sup&gt; vs. (0.4–8.3) × 10&lt;sup&gt;3&lt;/sup&gt; cm&lt;sup&gt;−3&lt;/sup&gt; for &lt;i&gt;S&lt;/i&gt;=0.07–0.86%) although the total aerosol particle number concentration was lower (1.2 × 10&lt;sup&gt;4&lt;/sup&gt; cm&lt;sup&gt;−3&lt;/sup&gt; vs. 2.3 × 10&lt;sup&gt;4&lt;/sup&gt; cm&lt;sup&gt;−3&lt;/sup&gt;). A comparison with related studies suggests that the fresh outflow from Chinese urban centers generally may contain more, but smaller and less hygroscopic aerosol particles and thus fewer CCN than the aged outflow from megacity regions

Size-resolved measurement of the mixing state of soot in the megacity Beijing, China: diurnal cycle, aging and parameterization

Soot particles are the most efficient light absorbing aerosol species in the atmosphere, playing an important role as a driver of global warming. Their climate effects strongly depend on their mixing state, which significantly changes their light absorbing capability and cloud condensation nuclei (CCN) activity. Therefore, knowledge about the mixing state of soot and its aging mechanism becomes an important topic in the atmospheric sciences. &lt;br&gt;&lt;br&gt; The size-resolved (30–320 nm diameter) mixing state of soot particles in polluted megacity air was measured at a suburban site (Yufa) during the CAREBeijing 2006 campaign in Beijing, using a volatility tandem differential mobility analyzer (VTDMA). Particles in this size range with non-volatile residuals at 300 &amp;deg;C were considered to be soot particles. On average, the number fraction of internally mixed soot in total soot particles (&lt;i&gt;F&lt;/i&gt;&lt;sub&gt;in&lt;/sub&gt;), decreased from 0.80 to 0.57 when initial &lt;i&gt;D&lt;/i&gt;&lt;sub&gt;p&lt;/sub&gt; increased from 30 to 320 nm. Further analysis reveals that: (1) &lt;i&gt;F&lt;/i&gt;&lt;sub&gt;in&lt;/sub&gt; was well correlated with the aerosol hygroscopic mixing state measured by a CCN counter. More externally mixed soot particles were observed when particles showed more heterogeneous features with regard to hygroscopicity. (2) &lt;i&gt;F&lt;/i&gt;&lt;sub&gt;in&lt;/sub&gt; had pronounced diurnal cycles. For particles in the accumulation mode (&lt;i&gt;D&lt;/i&gt;&lt;sub&gt;p&lt;/sub&gt; at 100–320 nm), largest &lt;i&gt;F&lt;/i&gt;&lt;sub&gt;in&lt;/sub&gt; were observed at noon time, with "apparent" turnover rates (&lt;i&gt;k&lt;/i&gt;&lt;sub&gt;ex &amp;rarr; in&lt;/sub&gt;) up to 7.8% h&lt;sup&gt;−1&lt;/sup&gt;. (3) &lt;i&gt;F&lt;/i&gt;&lt;sub&gt;in&lt;/sub&gt; was subject to competing effects of both aging and emissions. While aging increases &lt;i&gt;F&lt;/i&gt;&lt;sub&gt;in&lt;/sub&gt; by converting externally mixed soot particles into internally mixed ones, emissions tend to reduce &lt;i&gt;F&lt;/i&gt;&lt;sub&gt;in&lt;/sub&gt; by emitting more fresh and externally mixed soot particles. Similar competing effects were also found with air mass age indicators. (4) Under the estimated emission intensities, actual turnover rates of soot (&lt;i&gt;k&lt;/i&gt;&lt;sub&gt;ex &amp;rarr; in&lt;/sub&gt;) up to 20% h&lt;sup&gt;−1&lt;/sup&gt; were derived, which showed a pronounced diurnal cycle peaking around noon time. This result confirms that (soot) particles are undergoing fast aging/coating with the existing high levels of condensable vapors in the megacity Beijing. (5) Diurnal cycles of &lt;i&gt;F&lt;/i&gt;&lt;sub&gt;in&lt;/sub&gt; were different between Aitken and accumulation mode particles, which could be explained by the faster growth of smaller Aitken mode particles into larger size bins. &lt;br&gt;&lt;br&gt; To improve the &lt;i&gt;F&lt;/i&gt;&lt;sub&gt;in&lt;/sub&gt; prediction in regional/global models, we suggest parameterizing &lt;i&gt;F&lt;/i&gt;&lt;sub&gt;in&lt;/sub&gt; by an air mass aging indicator, i.e., &lt;i&gt;F&lt;/i&gt;&lt;sub&gt;in&lt;/sub&gt; = &lt;i&gt;a&lt;/i&gt; + &lt;i&gt;bx&lt;/i&gt;, where &lt;i&gt;a&lt;/i&gt; and &lt;i&gt;b&lt;/i&gt; are empirical coefficients determined from observations, and &lt;i&gt;x&lt;/i&gt; is the value of an air mass age indicator. At the Yufa site in the North China Plain, fitted coefficients (&lt;i&gt;a&lt;/i&gt;, &lt;i&gt;b&lt;/i&gt;) were determined as (0.57, 0.21), (0.47, 0.21), and (0.52, 0.0088) for &lt;i&gt;x&lt;/i&gt; (indicators) as [NO&lt;sub&gt;z&lt;/sub&gt;]/[NO&lt;sub&gt;y&lt;/sub&gt;], [E]/[X] ([ethylbenzene]/[m,p-xylene]) and ([IM] + [OM])/[EC] ([inorganic + organic matter]/[elemental carbon]), respectively. Such a parameterization consumes little additional computing time, but yields a more realistic description of &lt;i&gt;F&lt;/i&gt;&lt;sub&gt;in&lt;/sub&gt; compared with the simple treatment of soot mixing state in regional/global models