AAS21-01

Room:201B

Time:May 27 15:15-15:30

Volume Integral Equation Method Optimized for Black Carbon-Containing Aerosol Particles
NOBUHIRO, Moteki1∗
1

Department of Earth and Planetary Science, The University of Tokyo

We propose a robust scheme of volume integral equation method (VIEM) for light scattering and absorption by black carboncontaining aerosol particles: the fractal-like aggregates of absorbing black carbon (BC) spherules that may be mixed with nonabsorbing (or weakly absorbing) compounds. Conventionally, a particle volume has been uniformly approximated as a collectionof small volume elements (dipoles) on a cubic lattice (CL). In the proposed scheme, each BC spherule is considered as a spherical
dipole with original size, while remaining particle volume occupied by non-absorbing compounds is approximated by a collectionof dipoles on a CL. We call this as Spherule-Retained-Cubic-Lattice (SRCL) scheme. For several model BC-containing particles,
positive absorption bias of ˜30% persistent in the CL scheme is success-fully eliminated in SRCL scheme. The interaction matrix(i.e., discretized volume integral operator) associated with the SRCL scheme has less simple structure compared with that for CL
scheme. We propose some key strategies for mitigating memory and computational costs in solving the matrix equation in the
SRCL scheme.
Keywords: Atmospheric Radiation, Light Scattering Theory, Aerosol, Black Carbon

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AAS21-02

Room:201B

Time:May 27 15:30-15:45

Improved Technique to Measure the Size Distribution of Black Carbon Particles Suspended in Rainwater and Snow Samples
MORI, Tatsuhiro1∗ ; OHATA, Sho1 ; MOTEKI, Nobuhiro1 ; KONDO, Yutaka1
1

Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo

Black carbon (BC) aerosols strongly absorb visible solar radiation. Quantitative understanding of wet removal process, whichstrongly affects the spatial distribution of BC, is important to improve our understandings on climate change. For this purpose,a measurement technique for BC in rainwater and in snow samples has been developed, as a combination of a nebulizer and asingle particle soot photometer (SP2) (Ohata et al. 2011, 2013; Mori et al. 2014). We show two important improvements in thistechnique: (1) We have introduced a pneumatic nebulizer and experimentally confirmed its high extraction efficiency (∼50%)
independent of particle-size up to 2 µm. (2) We have extended the upper limit of detectable BC size range by the SP2 from 0.9µm to 4 µm by modifying a photo-detector for incandescence. Using this technique, we have measured the size-resolved massconcentration in air and in rainwater, simultaneously, during last summer in Tokyo. We observed significant amounts of BC
particles with diameters larger than 1µm in rain samples. The correlation between BC mass concentration in air and in rainwater
was high (r2 = 0.59), suggesting that the major sources of BC in rainwater were BC in the atmospheric planetary boundary layer.
The size distribution of BC in rainwater was shifted to larger size as compared with that in air, indicating that larger BC particles
in the air were removed more efficiently by precipitation.
Keywords: Black Carbon, Measurement, Wet deposition

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AAS21-03

Room:201B

Time:May 27 15:45-16:00

Measurements of the hygroscopicity and wet removal of black-carbon-containing particles in Tokyo
OHATA, Sho1∗ ; NOBUHIRO, Moteki1 ; MORI, Tatsuhiro1 ; KOIKE, Makoto1 ; TAKAMI, Akinori2 ;KONDO, Yutaka1
1

Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 2 Center for Regional Environmental Research, National Institute for Environmental Studies
Megacities are very large, concentrated anthropogenic sources of black carbon (BC) aerosols. Freshly emitted BC particles
inside megacities affect local air quality and regional and global climate. The microphysical properties (e.g., number size distribution, coating thickness, and hygroscopicity) of atmospheric BC-containing particles are important because their efficiency of
wet removal from the atmosphere can be highly dependent on these properties. In this study, we conducted intensive observationsof the hygroscopicity and wet removal of BC-containing particles in the urban atmosphere of Tokyo during summer 2014. The
number size distribution and coating thickness of BC-containing particles were measured with a standard Single Particle Soot
Photometer (SP2). The hygroscopicity of BC-free and BC-containing particles was measured with a modified (humidified) SP2.
In addition, the number size distribution of BC cores in rainwater was also measured with a nebulizer?SP2 system during rain
events.
Throughout the observation period, for BC-containing particles with a dry diameter of about 200 nm, the particles with smaller
BC fractions tended to represent greater water uptake, and the number fraction of the less hygroscopic (Growth factor <1.2 at
85% relative humidity) BC-containing particles was more than 70% of the total BC-containing particles. The measured average
number size distribution of BC cores in rainwater was larger than that in the surface air before precipitation began, and thedependence of the wet removal of BC-containing particles on their BC-core sizes was successfully explained by the measured
microphysical properties of BC-containing particles in the air and an assumed maximum supersaturation that the particles would
have experienced during rain events. These measurement data indicated that BC-containing particles in Tokyo, especially particles with small BC cores (or with high critical supersaturation), were efficiently transported upward without being removed by
precipitation.

Keywords: black carbon, hygroscopicity, wet removal

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AAS21-04

Room:201B

Time:May 27 16:15-16:30

Evaluation of Refueling emissions and its OFPHIROYUKI, Yamada1∗ ; INOMATA, Satoshi2 ; TANIMOTO, Hiroshi2
1

National Traffic Safety and Environment Lavoratory, 2 National Institute for Environmental Study

Refueling emissions have been considered one of the main VOC sources in Japan. However there is only a few study which
discuss the emission mechanism and its detailed effect on total VOC emissions in Japan. We performed the experiments using
sealed housing evaporative determination (SHED) to evaluate the refueling emissions. For the measurement devices, we adopted
not only total hydrocarbon, but also the composition analysis using proton transfer reaction plus switchable reagent ion mass
spectrometry (PTR+SRI-MS) to estimate the ozone formation potential of refueling emissions. We also tested some provention
devices of refueling emissions.
Keywords: Refueling emissions, VOC, Ozone formation potential, PTR-MS

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AAS21-05

Room:201B

Time:May 27 16:30-16:45

Evaluation of black carbon radiative effect using a mixing state resolved three-dimensional
model
MATSUI, Hitoshi1∗
1

JAMSTEC

This study evaluates the uncertainties in black carbon (BC) and its optical and radiative parameters over East Asia (spring2009) using a BC mixing state resolved three-dimensional model that can explicitly calculate BC processes in the atmospheresuch as emissions, aging processes by condensation and coagulation, the enhancement of absorption and CCN activity by the
aging, activation to cloud, and dry and wet deposition. The focus of this study is the uncertainties in the size distribution and themixing state in emissions. One base case simulation and 14 sensitivity simulations are conducted to understand the variabilityof BC mass concentrations in column, absorption aerosol optical depth, and the radiative forcing by BC absorption due to theuncertainties in emissions. The variability of BC optical and radiative parameters is estimated to be 39-59%. This variability
corresponds to BC absorption forcing from -12.6 to 6.5 W m−2 at the surface and from 4.3 to 6.6 W m−2 at the top of atmosphere over East Asia, showing the importance of the treatment of the size and the mixing state in emissions. In contrast, thevariability of BC mass concentrations is 17% and smaller than that of BC optical and radiative parameters. Therefore, BC opticaland radiative parameters (BC mass concentrations) are more (less) sensitive to the size and the mixing state in emissions. This
result shows that the following two points are important in the estimation of BC radiative forcing. The first is to reduce theuncertainties in the size and the mixing state in emissions. The second is to improve the representation of BC mixing state andthe enhancement of BC absorption in aerosol models because most models do not treat them sufficiently. My analysis also showsthat coagulation and lens effect (absorption enhancement due to the change in BC mixing state) play important roles to make thedifferent variability between BC mass concentrations and BC optical and radiative parameters.
Keywords: aerosol, black carbon, mixing state, mixing state resolved three-dimensional model, absorption enhancement, radiative forcing

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AAS21-06

Room:201B

Time:May 28 09:00-09:15

Atmospheric Processing of Combustion Aerosols as a Source of Soluble Iron to the OpenOcean
ITO, Akinori1∗
1

Japan Agency for Marine-Earth Science and Technology

Atmospheric processing of combustion aerosols may promote transformation of insoluble iron into soluble forms. Here, an
explicit scheme for iron dissolution of combustion aerosols due to photochemical reactions with inorganic and organic acids
in solution is implemented in an atmospheric chemistry transport model to estimate the atmospheric sources of bioavailable
iron. The model results suggest that deposition of soluble iron from combustion sources contributes more than 40% of the totalsoluble iron deposition over significant portions of the open ocean in the Southern Hemisphere. A sensitivity simulation using
half the iron dissolution rate for combustion aerosols results in relatively small decreases in soluble iron deposition in the ocean,compared with the large uncertainties associated with iron solubility at emission. More accurate quantification of the solubleiron burdens near the source regions and the open ocean is needed to improve the process-based understanding of the chemical
modification of iron-containing minerals.
Keywords: Global environmental change, Atmospheric deposition, Soluble iron, Biomass burning

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AAS21-07

Room:201B

Time:May 28 09:15-09:30

Adjoint of the coupled Eulerian-Lagrangian transport model
BELIKOV, Dmitry1∗ ; MAKSYUTOV, Shamil2 ; YAREMCHUK, Alexey4 ; GANSHIN, Alexander5 ;ZHURAVLEV, Ruslan5 ; AOKI, Shuji61

National Institute of Polar Research, Tokyo, 2 National Institute for Environmental Studies, Tsukuba, 3 Tomsk State University,
Tomsk, Russia, 4 N.N. Andreev Acoustic Institute, Moscow, Russia, 5 Central Aerological Observatory, Dolgoprudny, Russia,
6
Center for Atmospheric and Oceanic Studies, Graduate School of Science, Tohoku University, Sendai
We present the development of an inverse modeling system employing an adjoint of the global coupled transport model
consisting of the National Institute for Environmental Studies (NIES) Eulerian transport model (TM) and the Lagrangian plume
diffusion model (LPDM) FLEXPART. NIES TM is a three-dimensional atmospheric transport model, which solves the continuity
equation for a number of atmospheric tracers on a grid spanning the entire globe. The Lagrangian component of the forward
and adjoint models uses precalculated responses of the observed concentration to the surface fluxes and 3-D concentrations
field simulated with the FLEXPART model. Construction of the adjoint of the Lagrangian part is less complicated, as LPDMs
calculate the sensitivity of measurements to the surrounding emissions field by tracking a large number of particles backwards
in time. Developing of the adjoint to Eulerian part required significant manual code modification owing to the structure andcomplexity of the NIES model.
The overall advantages of our method are follows:
1. No code modification of Lagrangian model is required, making it applicable to combination of global NIES TM and any
Lagrangian model;
2. Once run, the Lagrangian output can be applied to any chemically neutral gas;
3. High-resolution results can be obtained over limited regions close to the monitoring sites (using the LPDM part), and atcoarse resolution for the rest of the globe (using the Eulerian part), minimizing aggregation errors and computation cost.
The results are verified using a series of test experiments. These tests demonstrate the high accuracy of the NIES-FLEXPART
adjoint when compared with direct forward sensitivity calculations. Adjoint of coupled NIES-FLEXPART model therefore
combines the flux conservation and stability of an Eulerian finite difference of adjoint formulation with the flexibility, accuracy
and high-resolution of a Lagrangian backward trajectory formulation.
The accuracy of the adjoint model is extensively verified by comparing adjoint to finite difference sensitivities. We show
acceptable tolerance of agreement obtained. The potential for inverse modeling using the adjoint of NIES- FLEXPART coupledmodel is assessed in a data assimilation framework using simulated observations, demonstrating the feasibility of exploiting CO2
measurements for optimizing CO2 emission inventories.

Keywords: carbon cycle, atmospheric transport, adjoint model, inverse modeling

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AAS21-08

Room:201B

Time:May 28 09:30-09:45

Estimating source-receptor relationships of tropospheric ozone: On the importance ofmodel horizontal resolution
SEKIYA, Takashi1∗ ; SUDO, Kengo1
1

Graduated School of Environmental Studies, Nagoya University

Ozone (O3 ) near the surface is harmful to human health and to vegetation including crops. It is recognized that intercontinental
transport of air pollutants affects air quality over a region. Task Force on Hemispheric Transport of Air Pollutants (TF HTAP)
coordinated a multi-model inter-comparison of 21 chemical transport models (CTMs) for assessing source-receptor relationships(i.e., the change in pollutants over a receptor region produced by change in emissions in a source region). Typical horizontal
resolution of HTAP models was about 300 km. A coarse-resolution model tends to overpredict ozone chemical production(e.g., Wild and Prather, 2006). However, it is unclear how model horizontal resolution affects source-receptor relationships oftropospheric ozone. We estimated source-receptor relationships of tropospheric ozone using the CHASER global CTM (Sudo etal., 2002) with medium-resolution (T42; 2.8 deg. x 2.8 deg.) and high-resolution (T106; 1.1 deg. x 1.1 deg.). The CHASER
model is also developed as an atmospheric chemistry component of the MIROC-ESM-CHEM earth system model, and simulates
detailed chemistry in the troposphere and the stratosphere with aerosols simultaneously. We conducted a 2010 control simulation
and a sensitivity simulation with 20% reduced emissions in East Asia to estimate source-receptor relationships. The model
results show that 20% East Asian emission reductions decrease surface O3 by 0.94 ppbv and by 0.75 ppbv over East Asia inspring respectively in the medium-resolution and high-resolution models. The East Asian emission perturbations also reduced
surface O3 by 0.27 ppbv and by 0.24 ppbv in spring over North America respectively in the medium-resolution and the highresolution models. Our results suggest that the high-resolution model tends to predict smaller decreases in surface O3 over East
Asia and North America in response to the East Asian emission reductions.
Reference
Wild and Prather (2006), J. Geophys. Res., 111, D11305, doi:10.1029/2005JD006605.
Sudo et al. (2002), J. Geophys. Res., 107, 10.1029/2001JD001113.

Keywords: tropospheric ozone, chemical transport model, source-receptor relationship, intercontinental transport

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AAS21-09

Room:201B

Time:May 28 09:45-10:00

Impacts of black carbon aging on its spatial distribution and radiative effect in the global
scale
OSHIMA, Naga1∗ ; TANAKA, Taichu2 ; KOSHIRO, Tsuyoshi1 ; KAWAI, Hideaki1 ; DEUSHI, Makoto1 ;KOIKE, Makoto3 ; NOBUHIRO, Moteki3 ; KONDO, Yutaka3
1

Meteorological Research Institute, 2 Global Environment and Marine Department, Japan Meteorological Agency, 3 Departmentof Earth and Planetary Science, Graduate School of Science, The University of Tokyo

Most aerosol components scatter solar radiation; however, black carbon (BC) aerosols efficiently absorb it and lead to heatingof the atmosphere. Because of these effects, the role of BC particles in the climate system has been recognized to be particularly
important. Freshly emitted hydrophobic BC particles become internally mixed with other water-soluble compounds throughaging processes and they are converted to hydrophilic BC. Internal mixing with sufficient water-soluble compounds enhances the
BC absorption efficiency of solar radiation, and the hydrophilic BC particles are able to serve as cloud condensation nuclei (CCN),
which can be removed from the atmosphere by precipitation. Consequently, aging processes of BC influence its atmospheric
lifetime and play an important role for the spatial distributions of BC and its radiative effects. However, a simple approach
using constant values of the conversion rate from hydrophobic BC to hydrophilic BC (such as 24 hours) has been widely usedin most global models and there were large uncertainties in estimating the spatial distribution of BC and its radiative forcing inprevious studies. Recent studies pointed out the necessity of an advanced parameterization of BC aging processes to improve thequantitative estimation of the climate impacts of BC.
Recently, Oshima and Koike [2013] developed a new parameterization of BC aging based on the physical and chemical
processes. In this parameterization, the conversion rate from hydrophobic BC to hydrophilic BC is expressed as a production rateof condensed materials normalized by the hydrophobic BC mass concentration. In this study, we applied this parameterization
to the global-scale aerosol model MASINGAR-mk2 included in the MRI’s earth system model [Yukimoto et al., 2012], whichenables the representation of spatial and temporal variations of the conversion rate of BC aging depending on atmosphericconditions (the original approach assumed the constant conversion rate of 1.2 days).
We performed the model calculation with the BC aging parameterization for 2008-2009. We find that the conversion time scales
from hydrophobic BC to hydrophilic BC exhibit distinct spatial variations and they were approximately one day and one week
over the source regions in East Asia and the remote regions in the Arctic, respectively. We also performed the model calculation
with the constant conversion rate (1.2 days) for the comparison. Over the source regions in East Asia, both calculations givesmall differences in BC mass concentrations and they reproduced the seasonal variations of BC mass concentrations observedby the surface measurements reasonably well. On the other hand, the both calculations give large differences in BC massconcentrations over the Arctic regions and the calculation with the parameterization improved the prediction of the BC massconcentration, which was underestimated in the constant-rate calculation.
The direct radiative forcing by BC (annually and globally averaged at the top of atmosphere) was approximately 0.3 W m−2 forthe calculation with the parameterization (approximately 0.2 W m−2 for the constant-rate calculation). This result indicates thatthe aging process of BC in the micro-scale can significantly impact on the spatial distribution and radiative forcing in the globalscale through the parameterization. However, the calculations shown in this study do not take into account the enhancement of
BC light absorption due to coatings and they may underestimate the direct radiative forcing. We will introduce model results
including the enhancement effect in this presentation.
References
Oshima, N., and M. Koike (2013), Geosci. Model Dev., 6 , 263-282, doi:10.5194/gmd-6-263-2013.
Yukimoto, S., et al. (2012), J. Meteor. Soc. Japan, 90A , 23-64, doi:10.2151/jmsj.2012-A02.

Keywords: Aerosol, Black carbon, Global aerosol model, Aging process, Transport, Radiative effects

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AAS21-10

Room:201B

Time:May 28 10:00-10:15

Interannual variabilities in tropospheric constituents during 2000-2013 simulated in achemistry-aerosol coupled climate
SUDO, Kengo1∗ ; ITO, Akihiko3
1

Graduate School of Environmental Studies, Nagoya University, 2 Japan Marine-Earth Science and Technology, 3 National Institute of Environmental Studies
Global distributions and abundances of tropospheric constituents (O3 , CH4 , NOy, CO, VOCs, NHx, SOx and aerosols) interannually change under the influences of meteorology (transport, temperature, water vapor, clouds, rain, etc.) and emissions
from anthropogenic/natural sources and biomass burning. In this study, we investigate interannual variability of troposphericconstituents during the years 2000 to 2013 in a chemistry-aerosol coupled climate model. The base chemical model used in thisstudy is CHASER (Sudo et al., 2002, 2007) coupled with the aerosol model SPRINTARS (Takemura et al., 2006). The CHASER
model, also developed in the framework of the MIROC earth system model (MIROC-ESM-CHEM), simulates detailed chemistry
in the troposphere and stratosphere with an on-line aerosol simulation including production of particulate nitrate and SOA. We
use the NCEP reanalysis data (FNL) for constraining the model’s meteorology.Anthropogenic and biomass burning emissions
are specified using the HTAP2 and MAC inventories, respectively. For biogenic VOCs emissions, we employ calculation by
the land ecosystem/trace gas emission model VISIT (Ito et al., 2008). Our results show that temporal variability (anomaly) insurface and lower tropospheric ozone very clearly correlates with that in CO especially in NH, indicating principal importanceof biomass burning emission in determining near-surface O3 variability; surface PM (PM2.5 ) in NH also coincides with CO.
Changes in middle to upper tropospheric O3, on the other hand, basically respond to variability in transport from the stratosphereand lightning NOx production. It is also demonstrated that temporal variability in tropospheric mean OH is largely controlled bytropospheric abundances of O3 , CO, and water vapor.
Keywords: tropospheric ozone, aerosol, PM2.5, methane, oxidation capacity, chemistry climate model

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AAS21-11

Room:201B

Time:May 28 10:15-10:30

Numerical Analysis of total nitrate deposition over marginal seas of Japan
ITAHASHI, Syuichi1∗ ; HAYAMI, Hiroshi1 ; UNO, Itsushi2 ; UEMATSU, Mitsuo3
1

Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, 2 Research Institute of Applied Mechanics, Kyushu University, 3 Atmosphere and Ocean Research Institute, The University of Tokyo
In China, due to the expanded economy growth, anthropogenic NOx emissions increased more than twofold between 2000
and 2010. Aerosol nitrate and gas-phase nitrate produced from NOx deposite above ocean during long-range transport process,and the impacts on ocean-ecosystem are apprehensive. In this study, on the basis of regional chemical transport which cantreat the detailed behavior of air pollutants, we investigated the deposition of total nitrate from atmosphere into marginal seasof Japan. Analyzed period was on the year from 2002 to 2004. Chemical transport model can well reproduce the atmosphericconcentration and wet deposition amount by comparing the ground-based observation dataset of EANET. Above East China Sea(ECS), three-year averaged deposition amount of total nitrate was 252 Gg-N/year. Dry and wet deposition process respectively
accounted 60% and 40%. Deposition amount of fine-mode nitrate and coarse-mode nitrate respectively attributed 22% and 50%,
and the rest of 28% was gas-phase nitrate. During these period, anthropogenic NOx emissions from China was 5377 Gg-N/year,
therefore, the deposition amount of total nitrate over ECS was corresponded to 4.7%. Taking into account that the deposition
amount above China was 2039 Gg-N/year, the deposition amount over ECS was identified as 7.5% against to anthropogenic NOxemissions from China. In the conference presentation, we would like to present the analyzed results over Sea of Japan, Yellow
Sea, and Pacific open oceans, and discuss the correspondence with anthropogenic NOx emissions from China.
Keywords: marginal seas of Japan, aerosol nitrate, gas-phase nitrate, deposition amount, chemical transport model

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AAS21-12

Room:201B

Time:May 28 10:30-10:45

Contribution of Siberian forest fires to PM2.5 pollution in Japan
IKEDA, Kohei1∗ ; TANIMOTO, Hiroshi11National Institute for Environmental Studies

We examined the contribution from Siberian forest fires to PM2.5 pollution in Japan using a regional chemical transportmodel. In May 2003, several events resulting in PM2.5 concentrations exceeding Japan’s air quality standard for daily meanvalue (35 µg/m3 ) were observed at Rishiri in northern Japan. The model generally well reproduced the temporal variations of
PM2.5 including the elevated events. The simulations demonstrated that the PM2.5 enhancements during the events were mostly
attributed to biomass burning in Siberia, suggesting that the contribution from Siberian forest fires had a critical impact on thehigh PM2.5 days (>35 µg/m3 ). The contributions from Siberian biomass burning to the monthly mean PM2.5 concentrations
were estimated to be 64% at Rishiri and 45% at both Nonodake and Oki located in eastern and western Japan, respectively,
suggesting that Siberian forest fires had a large impact on air quality for the whole of Japan. Especially at Rishiri, the observed
PM2.5 concentrations and aerosol optical depth (AOD) from MODIS in May 2003 were much larger than those of the 10-year
average in May from 2001 to 2010. The trend in horizontal distribution for May 2003 was opposite to the long-term average;
PM2.5 and AOD in May 2003 were the highest in northern Japan.
Keywords: PM2.5, aerosol, forest fires, Siberia, transboundary pollution

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AAS21-13

Room:201B

Time:May 28 11:00-11:15

Observations of O3, CO, CO2 and CH4 concentrations at Happo and estimations of thesource by chemical transport model
OKAMOTO, Sachiko1∗ ; TANIMOTO, Hiroshi1 ; NARA, Hideki1 ; IKEDA, Kohei1 ; YAMAJI, Kazuyo2
1

National Institute for Environmental Studies, 2 Kobe University

A large increase in tropospheric O3 concentrations was observed during spring for the period from 1998 to 2006 at Mt.
Happo Observatory (36.7o N, 137.8o E, 1840 m asl), which is one of the Acid Deposition Monitoring Network in East Asia
(EANET) stations (Tanimoto, 2009). The increase in the springtime O3 reproduced by a regional chemistry-transport model
incorporating the updated anthropogenic emissions inventory in East Asia can only explain about half of the observed O3 increase(Tanimoto et al., 2009). On the other hand, previous source-receptor analysis by a global chemistry-transport model indicatedthat the contributions of local and regional sources can vary, depending on individual episodes (Wild et al., 2004). For better
understanding of the discrepancies between the model prediction and observational evidence, it is necessary to better characterize
air masses at Mt. Happo by simultaneous measurements of additional tracers like CO, CO2 , and CH4 .
Starting in July 2013, we have made continuous measurements of CO, CO2 and CH4 as well as O3 at Mt. Happo. We foundthat the O3 levels at Mt. Happo increased until 2007, and then the increase slowed down and now decreased to the same level asin 1990s. The CO concentrations observed for the period of 2013-2014 was found to be lower than those in 1990s. In particular,
the current CO levels were 50 ppbv lower than in 1990s during summer. In total, 44 events associated with O3 enhancement
were identified for the period from July 2013 to August 2014. Correlations of CO with CO2 and CH4 with CO2 were used to
identify possible source regions for individual episodes. Emission ratios (∆CO/∆CO2 and ∆CH4 /∆CO2 ) were calculated ineach event, and compared with the ratios estimated by the regional emission inventory in Asia (REAS; Kurokawa et al., 2013).
There is a discrepancy between two emission ratios. The∆CO/∆CO2 indicated that most events except summer were affected by
the emissions from East Asia. On the other hand, the ∆CH4 /∆CO2 indicated that most of events were caused by the emissions
from Japan and Korea. It is difficult to identify the source regions by the ratios only.
We compared the observations with the model calculations by CMAQ v4.7.1, a regional chemistry-transport model, with thehorizontal and vertical resolutions of 80 km and 37 layers, respectively. The model calculations well reproduced variability andseasonal changes of CO. For O3 , although the model prediction was higher than the observed, in particular during the summer
season, the model reproduced the O3 enhancement events reasonably well. The source regions inferred by the model will be
discussed in the presentation.
Keywords: ozone, carbon monoxide, methane, carbon dioxide

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AAS21-14

Room:201B

Time:May 28 11:15-11:30

Long-term variations of atmospheric methane concentration over Siberia derived fromaircraft and tower measurements
SASAKAWA, Motoki1∗ ; MACHIDA, Toshinobu1 ; ITO, Akihiko1 ; TSUDA, Noritsugu2 ; ARSHINOV, Mikhail3 ;DAVYDOV, Denis3 ; FOFONOV, Alexandrov3 ; KRASNOV, Oleg3 ; PATRA, Prabir4 ; ISHIJIMA, Kentaro4
1

National Institute for Environmental Studies, 2 Global Environmental Forum, 3 V.E. Zuev Institute of Atmospheric Optics, Russian Academy of Sciences, 4 Japan Agency for Marine-Earth Science and Technology

Methane measurements over Siberia are crucial for estimating global CH4 emissions since Siberia is estimated to containover 100 million ha of wetlands. We have been acquiring long-term records of atmospheric CH4 concentration in Siberia at 3
sites (Surgut, Novosibirsk, Yakutsk) using aircraft since 1993 and at a tower network since 2004 (JR-STATION: Japan-Russia
Siberian Tall Tower Inland Observation Network, Sasakawa et al., 2010, 2012). Observed CH4 concentrations at the tower sites
in West Siberia showed much higher than those observed at coastal background sites operated by NOAA in northern high latitudinal zone. They also exhibited clear seasonal cycle with double maxima in winter and summer. However increasing trend
observed in background sites did not appear in tower data due to high variability in concentration during summer and winter.
On the other hand, aircraft data did not have clear seasonal cycle but showed obvious increasing trend. Global stagnation in riseof CH4 concentration around 2000-2006 was observed in aircraft data over taiga sites (Novosibirsk, Yakutsk) but not clear overwetland site (Surgut). In Surgut, vertical difference of CH4 concentration in recent years between 1 km and 5.5 km altitude data
decreased less than 2/3 of that in early 1990’s. This weakening vertical gradient appeared in other altitude data (0.5-4 km) as
well. Simulation results with a chemistry-transport model (ACTM; Patra et al., 2009) suggested that transport influence on thistrend could be small. A regional emission tagged tracer simulation with the ACTM (Umezawa et al., 2014) indicated that theCH4 emissions from West Siberia and Europe could produce most extent of the vertical gradient. This finding thus suggested
that the sum of dominant emissions decreased in these 20 years.
References
Patra et al., J. Meteorol. Soc. Jpn., 87(4), 635-663, 2009.
Sasakawa et al., Tellus, 62B, 403-416, 2010.
Sasakawa et al., Tellus, 64B, 17514, doi:10.3402/tellusb.v64i0.17514, 2012.
Umezawa et al, Tellus, 66B, 23837, 2014.
Keywords: Siberia, methane, tower network, aircraft observation

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AAS21-15

Room:201B

Time:May 28 11:30-11:45

Variations of atmospheric methane concentration and its carbon and hydrogen isotopic
ratios at Churchill, Canada
FUJITA, Ryo1∗ ; MORIMOTO, Shinji1 ; UMEZAWA, Taku2 ; DOUG, Worthy3 ; AOKI, Shuji1 ;NAKAZAWA, Takakiyo1
1

Center for Atmospheric and Oceanic Studies, Graduate School of Science, Tohoku University, 2 National Institute for Environmental Studies, 3 Environment Canada
Methane (CH4 ) is the second most important anthropogenic greenhouse gas after CO2 . High-precision measurements ofcarbon and hydrogen stable isotopic ratios of CH4 (δ 13 CH4 and δD-CH4 ) provide additional constrains to contributions of individual CH4 sources to atmospheric CH4 variations. Since 2007, we have conducted an air-sampling program at Churchill,
Canada (58.44’N, 93.50’W) on the northern perimeter of the Hudson Bay Lowland, the second largest wetland area in the world
i.e. one of the most important CH4 source regions at northern high latitudes. In this study, we present temporal variations ofCH4 , δ 13 CH4 and δD-CH4 at this site.
We observed long-term increase in the CH4 concentrations at Churchill since 2007, which is consistent with the trend reportedby the global observation networks such as NOAA/ESRL/GMD. The CH4 concentration at Churchill is generally higher than thatat Ny-Ålesund (78.55’N, 11.56’E), a northern high-latitude background station away from regional CH4 sources. On the other
hand, δ 13 CH4 and δD-CH4 at Churchill are lower than those at Ny-Ålesund, plausibly reflecting regional CH4 emissions. Clear
seasonal cycles of the CH4 concentration and δ 13 CH4 were observed; seasonal maximum and minimum of the CH4 concentration take place in January-February and June-July, respectively, while those of δ 13 CH4 were in May and October, respectively.
Seasonal cycles of δD-CH4 were obscure but observable. The seasonal phases of these variables were up to one month earlier
than those at Ny-Ålesund. The cause of the difference could be attributable to wetland emissions in the surrounding region.
Short-term variations of the CH4 concentration were observed year around, but pronounced in summer. By inspecting relationships between the CH4 concentration and the isotopic ratios, we found that the predominant CH4 source of the short-term CH4
variations is wetlands in summer but fossil fuels in winter.

Keywords: methane, carbon and hydrogen isotopic ratios, Hudson Bay Lowland, wetlands

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AAS21-16

Room:201B

Time:May 28 11:45-12:00

Temporal variation of methane profile observed with FTIR at Tsukuba
MURATA, Isao1∗ ; NAKAJIMA, Hideaki2 ; MORINO, Isamu3
1

Graduate School of Environmental Studies, Tohoku University, 2 Council for Science, Technology and Innovation, Cabinet
Office, Government of Japan, 3 National Institute for Environmental Studies
The vertical profiles of CH4 have been observed with high-resolution Fourier transform spectrometer at Tsukuba, Japan since2001. SFIT2 spectral fitting program was used to derive the vertical profiles from 3 spectral regions in 3 micrometer region.
CH4 is the second important contributor of the anthropogenically enhanced greenhouse effect but there are many uncertainties
in the source variations.
Daily averaged CH4 total column density kept a level from 2001 to 2006, then increased from 2007 to 2008, and again kept
a level from 2009 to 2014. Tropopause height shows no significant change between before and after 2007, indicating stable
dynamical situation. Derived CH4 profiles show that the increase occurred mainly in the troposphere.
Keywords: FTIR, Greenhouse Gas, Methane

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AAS21-17

Room:201B

Time:May 28 12:00-12:15

Atmospheric methane measurement by open-path laser methane instrument at paddy fields
in India
HIDEMORI, Takehiro1∗ ; MATSUMI, Yutaka1 ; NAKAYAMA, Tomoki1 ; SASAGO, Hiroshi1 ; KAWASAKI, Masahiro1 ;IMASU, Ryoichi2 ; ADACHI, Minaco3 ; TAKEUCHI, Wataru3 ; TERAO, Yukio4 ; NOMURA, Shohei4 ;MACHIDA, Toshinobu4 ; TAKAHASHI, Kenshi5 ; DHAKA, Surendra6 ; SINGH, Jagmohan6
1

Solar-Terrestrial Environment Laboratory, Nagoya University, 2 Atmosphere and Ocean Research Institute, The University ofTokyo, 3 The University of Tokyo, Institute of Industrial Science, 4 National Institute for Environmental Studies, 5 Research Institute for Sustainable Humanosphere, Kyoto University, 6 Rajdhani College, Univ. of Delhi
Methane is the second important greenhouse gas after carbon dioxide, and increasing importance to the Earth’s radiative budget. To better quantify methane emissions, their regional and temporal distribution, and attribution to the different methane
sources is needed.Satellite observations offer the possibility of sensing methane globally and retrieving methane abundances inremote areas and can help with interpretation of sparse ground based measurement. In southeast and south Asia, the previous
satellite observations suggest that the emission from rice paddies is significant and important source of methane during rainyseason. However, there are large uncertainties in quantitative estimation of methane emission in these areas and there are needs
for more certification between satellite and ground based measurements. In remote areas with insufficient infrastructure, airsampling and subsequently analysis are typical and reliable method for gas analysis. We developed the methane concentration
measurement system which can make a continuous observation to interpolate the data of sampled air between each sampling
period and we have operated the developed system at rural area in India.
The developed measurement system consists of gas sensor, power supply, data logger, remote control instruments and telecommunication equipment. The methane gas sensor is used a laser methane measurement instrument (LaserMethane, ANRITSUCORPORATION) which is a portable detector with low electric consumption, easy maintenance, and outdoor use. Remote sensing of methane is accomplished by means of infrared absorption spectroscopy with near-IR diode laser using reflected light froma reflector located at several tens meters away from the detector. High sensitivity is achieved by the second-harmonic detection of
wavelength modulation spectroscopy. It can quickly and selectively detect the integral methane concentration on the optical pathof the laser beam. To measure the methane concentration at paddy field in India, the methane measurement system was installedat rural area (Sonepat, Haryanea) on the north of Delhi and has been operated since the winter of 2014. The air sampling alongwith our measurement has been carried out once a weak currently. The methane concentration from the laser instrument canbe corrected with the more precise value of the sampled air. To establish how to correct the data and calibrate the system, we
performed both of laboratory experiment and field measurement. We will present about the development of the open-path laser
methane measurement system and the recent results of field measurement in India.

Keywords: methane, open-path laser spectroscopy, paddy field, India

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AAS21-18

Room:201B

Time:May 28 12:15-12:30

Relationship between interannual variation in the changing rate of APO trend at Cape
Ochi-ishi and PDO
TOHJIMA, Yasunori1∗ ; MUKAI, Hitoshi1 ; MACHIDA, Toshinobu1 ; TERAO, Yukio1
1

National Institute for Environmental Studies

Since atmospheric potential oxygen (APO=O2 +1.1xCO2 ) mainly reflects the air-sea gas exchange of O2 and CO2 by definition,
the spatio-temporal variations in APO are expected to constrain the ocean biogeochemical process and dynamics. Here we
examine the relationship between temporal variations in APO trend observed at Cape Ochi-ishi (COI; 43.2o N, 145.5o E) and
the Pacific Decadal Oscillation (PDO) index to investigate the causes for the inter-annual variations in the APO trend. The
PDO is a long-term Pacific climate variability, having two extreme phases which is classified by basin-scale patterns of the sea
surface temperature (SST) anomaly. When the SST anomalies are cool in the northern North Pacific and warm in the tropical
Pacific, the PDO index has positive value. And the opposite pattern of the SST anomalies correspond to the negative PDO
index. The cool SST enhances the ocean vertical ventilation which brings deeper waters with depleted O2 to the surface, causing
the O2 ingassing. The cool SST also enhances the ingassing flux by increasing gas solubility. To the contrary, the enhanced
ocean vertical ventilation brings the subsurface nutrients to the surface, enhancing the O2 outgassing through the increase in
the ocean primary production. Thus, the correlation analysis between the changing rate of the APO trend (dAPO/dt) at COI
and the PDO index would allow us to investigate how the SST anomaly in the northern North Pacific affect the air-sea gas
exchanges. Unfortunately, there is no significant correlation between dAPO/dt and the POD index. However, when dAPO/dt
and the PDO index are decomposed into the middle (0.3<f<0.6 cycle/yr) and low (f<0.3 cycle/yr) frequency domains by using
a digital filtering technique, the scatter plots of the middle-term and long-term variations show significant negative and positive
correlations, respectively. These results might suggest that the ventilation/thermal effect is dominant for the middle-term SST
variation while the biotic effect exceeds it for the long-term SST variation.
Keywords: APO, atmospheric oxygen, PDO, atmospheric CO2, air-sea gas exchange

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AAS21-19

Room:201B

Time:May 28 12:30-12:45

Variations in the atmospheric Ar/N2 and APO observed at Tsukuba, Ochi-Ishi, Hateruma
and Minamitorishima, JapanISHIDOYA, Shigeyuki1∗ ; MURAYAMA, Shohei1 ; TOHJIMA, Yasunori2 ; TSUBOI, Kazuhiro3 ;MATSUEDA, Hidekazu3 ; TAGUCHI, Shoichi1 ; PATRA, Prabir4 ; KONDO, Hiroaki1
13

National Institute of Advanced Industrial Science and Technology (AIST), 2 National Institute for Environmental Studies (NIES),
Meteorological Research Institute (MRI), 4 Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

Atmospheric Ar/N2 ratio is a unique tracer of spatiotemporally-integrated air-sea heat fluxes, and expected to be a new tool tovalidate changes in the global ocean heat content (e.g. Keeling et al. 2004; Cassar et al., 2008). The Ar/N2 ratio is also usefulto estimate thermal and biological components of Atmospheric Potential Oxygen (APO = O2 +1.1xCO2 ) separately, so that it
will contribute to better understanding of the oceanic carbon cycle. Therefore, we have developed a high-precision measurement
system of the atmospheric Ar/N2 ratio and APO (Ishidoya and Murayama, 2014), which is applicable both for continuous observations and analyses of discrete flask air samples, and started systematic observations of the Ar/N2 and APO at Tsukuba (36N,
140E) and Hateruma Island (24N, 124E), Japan since 2012 and at Cape Ochi-Ishi (43N, 146E) and Minamitorishima Island (24N,
154E), Japan since 2013. Clear seasonal cycles of the Ar/N2 ratio were observed at all the sites, and the peak-to-peak amplitudesof the seasonal cycles were in the range of 15 - 50 per meg. The observed amplitudes were found to be significantly larger thanthose calculated using atmospheric transport models and the seasonal air-sea N2 fluxes climatology (TransCom fluxes; Garcia
and Keeling et al., 2001) with a scaling factor to convert changes in the atmospheric N2 concentration to those in the Ar/N2 ratio(Blaine, 2005). We will also present preliminary estimations of the thermal and the biological APO at our sites by using theobserved seasonal Ar/N2 and APO cycles.
Acknowledgements
We would like to acknowledge N. Oda and F. Shimano, Global Environmental Forum, and many staffs of Japan Meteorological
Agency for their supporting the observations.
References
Blaine, T. (2005) Continuous Measurements of Atmospheric Argon/Nitrogen as a Tracer of Air-Sea Heat Flux: Models, Methods, and Data. PhD Thesis, University of California, San Diego.
Cassar, N. et al. (2008) An improved comparison of atmospheric Ar/N2 time series and paired ocean-atmosphere model predictions. J. Geophys. Res., 113, D21122. DOI: 10.1029/2008 JD009817.
Garcia, H. & Keeling, R. (2001) On the global oxygen anomaly and air-sea flux. J. Geophys. Res, 106, 31155-31166.
Ishidoya, S. & Murayama, S. (2014) Development of high precision continuous measuring system of the atmospheric O2 /N2and Ar/N2 ratios and its application to the observation in Tsukuba, Japan. Tellus B, 66, 22574, http://dx.doi.org/ 10.3402/tellusb.v66.22574.
Keeling, R. et al. (2004) Measurement of changes in atmospheric Ar/N2 ratio using a rapid-switching, single-capillary mass
spectrometer system. Tellus B, 56, 322-338.

Keywords: Atmospheric Ar/N2 ratio, Atmospheric Potential Oxygen (APO), Air-sea heat flux

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AAS21-20

Room:201B

Time:May 28 14:15-14:30

Seasonal variations of nitrogen and oxygen isotopic signature of atmospheric nitrate incoastal Antarctica
ISHINO, Sakiko1∗ ; HATTORI, Shohei1 ; CAILLON, Nicolas2 ; BARBERO, Albane2 ; GAUTIER, Elsa2 ;JOURDAIN, Bruno2 ; PREUNKERT, Susanne2 ; LEGRAND, Michel2 ; YOSHIDA, Naohiro1 ; SAVARINO, Joel2
1

Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Japan, 2 Universite Grenoble
Alpes/CNRS, LGGE, F-38000 Grenoble, France
Nitrate (NO3 − ) is the end-product of oxidation of nitrogen oxides (NOX =NO+NO2 ) in the atmosphere and one of the major
ions preserved in Antarctic snow and ice. Therefore, there has been great interest in using concentration and isotopic signatureof nitrate in ice cores to reconstruct past atmospheric NOX sources and their oxidation processes to nitrate. For interpretation of
nitrate records in Antarctic ice cores, it is necessary to know the long-term changes of concentration and isotopic compositions(15 N/14 N, 17 O/16 O and 18 O/16 O) of nitrate in the atmosphere which deposits on the surface snow. In this study, we present
seasonal variation of nitrogen and triple oxygen isotopic composition of nitrate collected at French Antarctic Station Dumontd’Urville (66o 40’S, 140o 01’E) throughout the year 2011. The significant increase of nitrate concentration during spring andsummer period was observed and 15 N were depleted in the nitrates, indicating that there was the substantial NOX input to theatmosphere by photolysis of nitrate in the surface snow. In addition, relatively low 17 O excess in summer period suggests that
NOX oxidation to nitrate by OH radicals was increased. On the other hand, high 17 O excess with low concentration in fall
and winter period suggests that OH oxidation pathway was depleted and other oxidation pathways related to O3 were dominant.
Additionally, the small nitrate increase in winter period might be attributed to the transport of stratospheric nitrate to troposphere
due to the formation of polar stratospheric clouds. In the presentation, we will discuss the long-term change of the seasonal
trends and compare the result with that of 2001 year-round isotopic analysis using nitrate aerosols at the same station.
Keywords: Antarctic, Aerosol, Nitrate, Stable isotopic analysis

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AAS21-21

Room:201B

Time:May 28 14:30-14:45

Determination on the triple oxygen isotopic composition of atmospheric nitrous acid
(HONO)NAKANE, Ray1∗ ; OHYAMA, Takuya1 ; NAKAGAWA, Fumiko1 ; TSUNOGAI, Urumu1 ; NOGUCHI, Izumi2 ;YAMAGUCHI, Takashi2
1

Graduate School of Environmental Studies, Nagoya University, 2 Hokkaido Institute of Environmental Sciences

The photolysis of nitrous acid (HONO) has been recognized as a potentially important source of OH radicals, which is known
as a major oxidant in the atmosphere removing reductive trace gases such as methane and NMHCs. There are two major formation pathways to produce atmospheric HONO, one is a process so-called “direct emission” in which HONO emits directlyfrom various sources on the ground and the other “secondary formation” in which HONO is produced by chemical reaction of
nitrogen compounds in the atmosphere. Their contributions to the production of atmospheric HONO, however, have not been
well understood.
In order to quantify the contribution of HONO derived from secondary formation, we determined a triple oxygen isotope, ∆17
O value of atmospheric nitrous acid (HONO). ∆ 17 O value of HONO produced via secondary formation is expected to havehighly positive values as those of O3 (∆ 17 O = +30 ±10 ‰), while no ∆ 17 O anomaly (∆ 17 O = 0 ‰) should be observed for
HONO which is emitted directly from various sources on the ground.
Atmospheric HONO was collected using filter-pack method (Noguchi et al., 2007) in which HONO accumulates on the K2 CO3
impregnated filter as NO2 − . Since HONO is collected as NO2 − , we must be careful about oxygen exchange between NO2 − andH2 O on the filter. If the sampling period becomes longer, ∆ 17 O of HONO could become smaller than the original value due torapid oxygen exchange between NO2 − and H2 O on the filter. Therefore, in order to decide appropriate sampling periods for ∆17
O measurement of HONO, we conducted a field sampling of atmospheric HONO during December 15-26, 2014, at Hokkaido
Institute of Environmental Sciences, Sapporo, Japan. We arranged seven different periods (half a day, one day, two days, threedays, four days, one week and two weeks) for atmospheric HONO collection. We also set two kinds of sampling flow rate for
HONO sampling; faster flow rate (10 L/min) for shorter sampling periods (from half a day to three days) and slower flow rate
(4 L/min) for longer sampling periods (from four days to two weeks). HONO-derived NO2 − on the filter was extracted to purewater. After that, it was reduced to N2 O using HN3 and then converted to O2 via thermal decomposition and then introduced to
IRMS for ∆ 17 O measurement. The concentration of NO2 − and NO3 − in the extracted water were measured by traditional ion
chromatography to calculate NO2 − yield (ratio of NO2 − among the sum of NO2 − and NO3 − ) on the filter.
We found clear difference on NO2 − yield absorbed on the filter between the two sample flow rates. Low flow late (4 L/min)
result in lower NO2 − yield of around 79% on average which coincide well with those reported previously (76%, Ohyama et al.,2012). Very high NO2 − yield of more than 98% were observed in the filter collected at high rates (10 L/min). We concluded that
we could prevent NO3 − formation via reaction of NO2 − with O3 by collecting HONO in the condition of higher sample flowrate.
The result of ∆ 17 O value of HONO ranged from +6 ‰ to +9 ‰ through the observation periods. We could not find any ∆17
O depletion due to oxygen exchange between NO2 − and H2 O on the filter during the collection periods. Assuming that ∆17
O value of HONO derived from secondary formation is +35 ‰, the contribution of HONO produced via secondary formation
to atmospheric HONO was estimated to be about more than 20% demonstrating its significance on the formation pathway of
atmospheric HONO in the winter of urban area.

Keywords: HONO, nitrous acid, triple oxygen isotope, source, winter, Sapporo

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AAS21-22

Room:201B

Time:May 28 14:45-15:00

Determination of partitioning of alpha-pinene ozonolysis products between gaseous andaerosol phases
INOMATA, Satoshi1∗ ; TANIMOTO, Hiroshi1 ; SATO, Kei1 ; FUJITANI, Yuji1 ; YAJIMA, Ryoji2 ;SAKAMOTO, Yosuke2 ; HIROKAWA, Jun2
1National Institute for Environmental Studies, 2 Hokkaido University

Organic material accounts for a substantial fraction of atmospheric fine particulate matter, which directly and indirectly affects
the global climate as well as human health. Many gas-phase organic compounds undergo oxidation in the gas phase to yieldproducts, generally oxygenated, that have vapor pressures sufficiently low that they are partitioned between the gas and aerosol
phases. Such compounds are often referred to as semi-volatile organic compounds (SVOCs) and, when present in the aerosol
phase, as secondary organic aerosols (SOAs). Quantification of the impacts of SOAs requires understanding their chemical composition and processes of formation as well as mass yields. In particular, because a systematic underestimation of simulated SOA
production increases with air mass ageing, speciation of the SVOCs produced by gaseous oxidation is essential. In addition,
information about the partitioning of each SVOC between the gaseous and condensed phases as well as the reactions of thecondensed SVOCs within the particulate phase is important for the description of SOA formation. We use chemical ionizationmass spectrometry to identify SVOCs in both the gaseous and the aerosol phases and to estimate the gas-aerosol partitioningof each SVOC. By using the same technique to measure SVOCs in both the gaseous and the aerosol phases, we were able todetermine the partitioning of each SVOC between the gaseous and aerosol phases from the ratio of ion signals, without knowing
the concentration of each SVOC. This ability to partition each SVOC between the gaseous and aerosol phases is a strong pointof this approach, because most chemical species in SOAs are thought to be multifunctional, and determining their concentrations
seems to be impossible. In the present study, we used two proton transfer reaction-mass spectrometers for real-time measurements of SVOCs produced in α-pinene ozonolysis in both the gaseous and the aerosol phases and determined the partitioningof each SVOC between the gaseous and aerosol phases. Time profiles of the SVOCs in both the gaseous and the aerosol phases
were compared. This work was supported by the Environmental Research and Technology Development Fund (5-1408) of the
Ministry of the Environment, Japan.
Keywords: Secondary organic aerosol, Gas-particle partitioning, Chemical ionization-mass spectrometry, Proton transfer reactionmass spectrometry, alpha-Pinene, Ozonolysis

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AAS21-23

Room:201B

Time:May 28 15:00-15:15

Impact of oxidation processes on optical properties of isoprene SOAs
NAKAYAMA, Tomoki1∗ ; SATO, Kei2 ; IMAMURA, Takashi2 ; MATSUMI, Yutaka1
1

Solar-Terrestrial Environment Laboratory, Nagoya University, 2 National Institute for Environmental Studies

Isoprene is the most abundant volatile organic compounds (VOCs) emitted from biosphere and is known as one of the precursors of secondary organic aerosols (SOAs) in the atmosphere. The formation yield of the isoprene-SOAs is considered to beenhanced in the presence of acidic seed particles such as sulfuric acid. Recently, it has been suggested that some organic aerosols,
which is called “brown carbon” , can absorb solar radiation, especially at the ultraviolet (UV) and shorter visible wavelengths andcontribute to the radiation balance and photochemical reactions in the atmosphere. However, no experimental study on complex
refractive index (RI) of the SOAs generated from the isoprene has been reported. In this work, wavelength dependence of thecomplex RI values of the SOAs generated in the oxidation of isoprene with OH, NO3 , and O3 in the presence or absence of SO2
have been examined.
The SOAs were generated in a 6 m3 Teflon coated stainless steel photochemical smog chamber. In the OH oxidation experiments, the reaction mixture of isoprene and NO in the presence or absence of SO2 (sulfuric acid precursor) was continuously
irradiated by UV light after the addition of a small amount of methyl nitrite as a source of OH radicals. In the ozonolysis
experiments, isoprene was reacted with O3 in the presence or absence of CO (OH scavenger) and SO2 . In the NO3 oxidation
experiments, ozone was added to the mixture of isoprene and NO2 in the presence of SO2 . The optical properties of the SOAs
were measured by two photoacoustic spectrometers (PASS-3 and PAX, absorption and scattering at 375, 405, 532, 781 nm) and acustom-built cavity ring-down spectrometer (CRDS, extinction at 532 nm). Chemical properties of aerosols were also measured
by an Aerodyne aerosol mass spectrometer (ToF-AMS). The size distributions of SOAs were measured by a scanning mobility
particle sizer (SMPS).
Absorption, scattering, and extinction efficiencies of SOAs are calculated by dividing the absorption, scattering, and extinction
coefficients by total mobility cross sections measured with the SMPS. The RI of the SOAs is determined by comparing the size
parameter dependence of extinction, scattering, and absorption efficiencies with Mie theory. The significant imaginary part values of RI at 405 and 532 nm are obtained for the SOAs generated in the OH oxidation of isoprene in the presence of SO2 , while
the imaginary part values are negligible for the SOAs generated in the ozonolysis (in the presence of OH scavenger) and NO3oxidation of isoprene. In the presentation, relationship with chemical properties and the atmospheric implications of the results
will also be discussed.

Keywords: Isoprene, Secondary organic aerosol, Aerosol optical properties, Complex refractive index, Brown carbon

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AAS21-24

Room:201B

Time:May 28 15:15-15:30

Effects of relative humidity on tetrol formation from isoprene/NO photo-oxidation
SATO, Kei1∗ ; OKUMURA, Motonori2 ; TAKAMI, Akinori1 ; IMAMURA, Takashi11National Institute for Environmental Studies, 2 Kyoto University

2-Methyltetrols, molecular markers of isoprene secondary aerosol, are produced by the particle-phase hydrolysis of organonitrate esters (Sato, 2008; Szmigielski et al ., 2010; Jacobs et al ., 2014) and/or the particle-phase oxidation of isoprene epoxydiols(Jacobs et al ., 2014) during the isoprene/NOx photo-oxidation. The effects of relative humidity, acid and base on 2-methyltetrol
formation from the isoprene/NO photo-oxidation were investigated. We used a 6-m3 Teflon bag and a 6-m3 stainless steel chamber for humid and dry conditions, respectively. 2-Methyltetrol formation under humid conditions (RH ' 80%) was enhanced in
the presence of sulfur dioxide and was also enhanced in the presence of ammonia. In contrast, 2-methyltetrol formation under
dry conditions (RH <1%) was less catalyzed or suppressed in the presence of sulfur dioxide. The ratio of total 2-methyltetrol
mass to total organic aerosol mass was 0.21 ‒ 18 wt% under various present conditions. 2-Methyltetrol formation in the aqueous
solution of aerosol sample was also investigated, and was found to be enhanced by both the acid and the base. The present results
show that the presence of water is critical for acid-catalyzed 2-methyltetrol formation from isoprene/NO photo-oxidation. The
ester hydrolysis will be a major pathway for 2-methyltetrol formation because it was enhanced by the base.
This work was supported by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (No.
25340021, FY2013 ‒ 2015). K.S. and M.O. thank Professor Susumu Tohno of Kyoto University for supplying a GC/MS instrument.
References: Sato, K. (2008) Atmos. Environ. 42, 6851 ‒ 6861. Szmigielski, R. et al . (2010) Atmos. Res. 98, 183 ‒ 189.
Jacobs, M. I. et al . (2014) Atmos. Chem. Phys . 14, 8933 ‒ 8946.
Keywords: biogenic volatile organic compound, secondary organic aerosol, organic nitrate, aqueous-phase reaction, environmental chamber

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AAS21-25

Room:201B

Time:May 28 15:30-15:45

Continuous observations of atmospheric HCHO by MAX-DOAS at Yokosuka, Japan:
Verification and correlation with ozone
KANAYA, Yugo1∗ ; POSTYLYAKOV, Oleg2 ; IRIE, Hitoshi3 ; TAKASHIMA, Hisahiro4
1

DEGCR/JAMSTEC, 2 Institute of Atmospheric Physics, Russian Academy of Sciences, 3 Chiba University, 4 Fukuoka University

Tropospheric ozone is an important greenhouse gas with the third largest global warming effect after CO2 and CH4. Its photochemical production in the atmosphere is not quantitatively understood, partly because of the large uncertainties in the amountand origins of the volatile organic compounds (VOCs) in the atmosphere serving as precursors of ozone. Accurate observationsof formaldehyde (HCHO), formed from VOC oxidation simultaneously with ozone, would provide pivotal information of the
VOC emission rates and ozone production mechanisms. This study focuses on the measurements of HCHO in the urban area,
specifically at Yokosuka (35.32 degN, 139.65 degE), Japan. Appropriateness of the observations was verified and then the correlation with ozone concentrations was studied.
Differential slant column densities of HCHO were derived from MAX-DOAS spectrum observations (336.5 - 359 nm) at
Yokosuka and then converted to the vertical column densities/profiles using aerosol information retrieved simultaneously. We
obtained observational data from October 2007 to December 2013, and from 08H (0800-0900 JST) to 15H in winter and from
06H to 17H in summer. The HCHO concentrations at the lowest layer derived from MAX-DOAS agreed quite well with themonthly ground-based observations of HCHO conducted at Oppama site, 2 km west of our location. Although we showed thatrecent satellite observations of HCHO provided reasonable agreement with MAX-DOAS over a rural site near Moscow, Russia,
poorer agreement was obtained at Yokosuka, potentially affected by the spatial inhomogeneity in the HCHO concentrations in ornear the urban region.
Monthly averages of the tropospheric vertical column density of HCHO derived from MAX-DOAS at 13H showed clear seasonal variation with maxima during July-September ((1.4-2.0)x10ˆ16 molecules cmˆ-2) and minima during December-March.
The temporal variation during summer was quite similar to that of ozone concentrations observed at Oppama, while the HCHO
levels were quite low in April/May, when the ozone concentration was even higher. The HCHO partial column in the lowest
1 km altitude range at 13H during June-August showed tight positive correlation with the surface ozone concentrations. These
analyses suggested that the MAX-DOAS observations of HCHO are successful in quantifying HCHO secondarily produced in
the atmosphere by photochemistry and that the short-lived HCHO would be a useful tracer to differentiate in-situ ozone production from long range transport.

Keywords: Tropospheric photochemistry, Volatile organic compounds, Urban atmosphere, Ozone precursors

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AAS21-26

Room:201B

Time:May 28 15:45-16:00

Evaporation of aerosol particles upon heating in a transmission electron microscope
ADACHI, Kouji1∗
1

Meteorological Research Institute

Thermal property (e.g., evaporation temperature) of atmospheric aerosol particles is important to measure and classify their
species using, for example, an aerosol mass spectrometer, a thermos denuder, and thermal method for elemental carbon/organiccarbon (EC/OC). However, it is largely unknown about the thermal behavior of ambient aerosol particles especially organic
aerosol particles and their mixture with inorganic materials. Therefore, evaporation temperatures of ambient aerosol particles
with their compositions need to be determined.
This study uses a transmission electron microscope (TEM) and a heating holder, which can heat samples on TEM grids >1000℃ while observing their shapes. Thus, it is possible to observe particle evaporation process upon heating. The TEM chamber
is in vacuum (˜0.00001Pa) and lacks of oxygen. Thus, particle volumes on TEM grids changes through evaporation/sublimation
at specific temperature. In general, an aerosol mass spectrometer uses 600 ℃ to vaporize aerosol particles, a thermos denuder
uses 200-300 ℃ to remove volatile materials, and an EC/OC measurement use ˜500 ℃ to distinguish OC and EC. Thus aerosol
thermal properties were analyzed by heating from room temperature to 600 ℃.
This study mainly used ambient samples collected from biomass burning during Biomass Burn Observation Project (BBOP) in
2013. These samples were collected at North America using an aircraft. The results indicated that organic materials in biomassburning lost their volume while heating up to 600 ℃ but did not completely evaporate but remained residue, which is probably
due to charring of organic matters. Especially, spherical brown carbon organic particles occurring in biomass burning (tar balls)
left their volume by 30% at 600 ℃. The results imply that tar balls are difficult to measure their properties when assuming they
are volatile materials even at 600 ℃.
Acknowledgements: The author acknowledges the BBOP campaign team, especially L I Kleinman, A, J Sedlacek, and P R
Buseck, for their helps for the sampling and the analyses of BBOP samples.

Keywords: aerosol, heating, organic matter, transmission electron microscopy, biomass burning

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AAS21-27

Room:201B

Time:May 28 16:15-16:30

Speciation of sulfate in aerosols for the precise estimation of its global cooling effectMIYAMOTO, Chihiro1∗ ; YAMAKAWA, Yoshiaki1 ; SAKATA, Kohei2 ; MIYAHARA, Aya2 ; SUGA, Hiroki2 ;SAKAGUCHI, Aya3 ; TAKEICHI, Yasuo4 ; ONO, Kanta4 ; TAKAHASHI, Yoshio1
1

Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 2 Department of Earth andPlanetary Systems Science, Graduate School of Science, Hiroshima University, 3 Faculty of Pure and Applied Science, Universityof Tsukuba, 4 Institute of Materials Structure Science, KEK
Global cooling effect by aerosol is one of causes which influence earth’s climatic change (IPCC, 2013). In particular, sulfate
aerosols are known to cool the earth indirectly by forming cloud condensation nuclei (CCN) because of their high hygroscopicity.
However, the hygroscopicity can change depending on the sulfate species. For example, CaSO4 ·2H2 O is sulfate having low
hygroscopicity. Therefore, determination of sulfate species in aerosols is necessary to interpret the degree of cooling effect by
sulfate aerosols in environment.
In this study, aerosol sampling was conducted in Higashi-Hiroshima (34.40 N, 123.71 E), Hiroshima, Japan. In addition, thesamples were collected using two methods as to particle size. One method collected non-size-fractionated aerosols for about ayear from September 2012 to September 2013. The other method collected size-fractionated aerosol in various periods such as
winter when concentrations of anthropogenic aerosols were high (PA sample; collected from January 31 to February 1, 2013),
spring (March 4 to 9, 2013), summer (July 22 to August 5, 2013), and fall (November 11 to 25, 2013). For these samples, major
ion composition was measured by ion-chromatography, while chemical species of sulfur and calcium in the aerosol samples
were determined by X-ray absorption fine structure (XAFS) spectroscopy. Furthermore, to unravel the function of CCN bysulfate aerosols in more detail, samples for single particle analysis were collected on May 31, 2014 during a dust event, which
was analyzed individually using scanning transmission X-ray microscopy (STXM).
Atmospheric concentration of each major ion in the atmosphere had seasonal variation. Sulfate ion (SO4 2− ) concentration
was larger in PA, in which concentration of ammonium ion (NH4 + ) and nitrate ion (NO3 − ) were also larger than those in otherseasons. Meanwhile, size distribution of aerosol is important to determine its origin, because it is widely recognized that aerosol
larger than 1 µm diameter is of natural origin. On the other hand, particles finer than 1 µm is of anthropogenic origin. In general,
concentrations of SO4 2− and NH4 + were larger in finer particles. Therefore, it is strongly suggested that the aerosol sample
collected in this period was influenced by human activities. In spring, concentration of calcium ion (Ca2+ ) increased particularlyin the coarse particles, which suggests that its origin was from natural source.
Subsequently, sulfate species in the aerosol samples was determined using XAFS, where it was found that concentration
ratio of calcium sulfate (CaSO4 ·2H2 O) which has low hygroscopicity to total concentration of SO4 2− in the aerosol sample([CaSO4 ·2H2 O]/[SO4 2− ]t ) was larger in spring than that in PA. The abundance of CaSO4 ·2H2 O in atmosphere cannot be ignored
because of its comparatively high [CaSO4 ·2H2 O]/[SO4 2− ]t ratio, especially in spring. It was also found that indirect cooling
effect by sulfate will be small in spring due to the larger ratio of [CaSO4 ·2H2 O]/[SO4 2− ]t . To provide further details of theeffect by CCN function, Ca species of single particle samples in the dust period was determined using STXM. It was shown that
there was CaSO4 ·2H2 O at the surface of the particle, which is the site of the chemical reactions with other species in aerosols.
In addition, Ca(NO3 )2 ·4H2 O, which was minor Ca species in the bulk analysis, was also detected in the particles. Individual
analysis of single particle is important to determine minor species in aerosol samples, which leads to better understanding ofchemical processes in the atmosphere.
In conclusion, it was suggested that the degree of indirect cooling effects of sulfate aerosol can change seasonally because
concentrations of low hygroscopicity sulfate species in the atmosphere are variable.

Keywords: aerosol, speciation of sulfate, global cooling effect, X-ray absorption fine structure

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AAS21-28

Room:201B

Time:May 28 16:30-16:45

Interaction between oxalate aerosol and metal: stability and global cooling effect ofaerosol
YAMAKAWA, Yoshiaki1∗ ; SAKATA, Kohei2 ; MIYAHARA, Aya2 ; MIYAMOTO, Chihiro2 ; TAKAHASHI, Yoshio1 ;SAKAGUCHI, Aya3
1

University of Tokyo, 2 Hiroshima University, 3 University of Tsukuba

Photoreaction contributes to the formation and removal processes of oxalic acid that is a major component of organic aerosols.
Oxalic acid is formed by photooxidation of high molecular weight organic aerosols via glyoxylic acid, and decomposed into
carbon dioxide. In addition, previous study showed that oxalic acid forms insoluble metal-oxalate complex, which suggested
that global cooling effect of oxalic acid is lower than previous estimation because metal-oxalate complex does not work as cloud
condensation nuclei. Interaction between oxalic acid and metal might affect photoreactivity like hygroscopicity. In this study,
speciation of oxalic acid and measurement of reaction rate constant for photoreaction were conducted to evaluate the effect ofmetal for global cooling effect and photoreaction.
Size fractionated aerosol samples were collected at Higashi-Hiroshima in winter, spring, and summer. Speciation analysis ofoxalic acid was conducted by X-ray absorption fine structure (XAFS) spectroscopy for zinc (Zn), lead (Pb), and Calcium (Ca).
Photoreaction experiments were conducted by ultraviolet ray about oxalic acid and glyoxylic acid. Oxalic acid and glyoxylic
acid were measured by Total Organic Carbon (TOC) Analyzer and colorimeter using Schiff base, respectively.
As a result of speciation, Ca and Zn oxalate complexes were found in fine particles (<1.7 µm), but Pb complex was hardly
found. The ratio of metal-oxalate complexes to total oxalic acid was about 30% to 50% about each sample. This result showedthat the cooling effect of oxalic acid might be smaller than previous estimation.
As a result of photolysis experiments, half-life time of oxalic acid, Mg complex, and Zn complex is 19 minutes, 71minutes, and172minutes, respectively. This result showed that photoreactivity of oxalic acid was decreased due to the decrease of quantum
yield by forming metal-oxalate complexes. In contrast, photoreactivity of glyoxylic acid was increased by coexisting with Zn.
Photoreaction of glyoxylic acid to oxalic acid is addition reaction of oxygen, which differs that of oxalic acid to carbon dioxideby cutting carbon bond. It is thought that the reason why photoreactivity was improved is what Zn worked as catalyst.

Keywords: organic aerosol, oxalic acid, metal complex, photo reactivity, indirect effect

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AAS21-29

Room:201B

Time:May 28 16:45-17:00

Major ion composition in aerosol: As an new indicator of chlorine deficiency
SAKATA, Kohei1∗ ; SAKAGUCHI, Aya2 ; TAMENORI, Yusuke3 ; OGAWA, Masahiro4 ; TAKAHASHI, Yoshio5
1

Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, 2 Faculty of Pure and Applied Science, University of Tsukuba, 3 Japan Synchrotron Radiation Research Institute (JASRI), 4 SR-center Ritsumeikan University,
5
Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo

A large part of sodium and chlorine in aerosol particles are derived from surface seawater as sodium chloride (sea-salt; NaCl).
Sodium chloride in aerosol is altered to sodium nitrate (NaNO3 ) and sulfate (Na2 SO4 ) by the reaction with nitric acid (HNO3 )and sulfuric acid (H2 SO4 ) in atmosphere, respectively. In these reactions, gaseous HCl is emitted from sea-salt particles to theatmosphere, which is is called as chlorine deficiency. These are important chemical reactions to anthropogenic N, in the processof transport from continent to open ocean, and to H2 SO4 as scavenging process in atmosphere (Akimoto, 2014). However, detailprocesses of the chemical reaction and size-dependence of aerosol particles on this reaction are not clear. In order to clarify
these reactions/processes in aerosol, we employed mass fractions (MF) parameter to size-fractionated aerosol particles obtained
from land/continent and ocean. Direct speciation of Na was also conducted by soft X-ray absorption fine structure (XAFS)
spectroscopy to intercompare the abundance ratio of Na species to those estimated by MF.
Size-fractionated aerosol particles on land were collected by a high volume cascade impactor at Higashi-Hiroshima from December 2012 to March 2014. Marine total suspended particulate (TSP) and size-fractionated aerosol particles were collectedin the R/V Hakuho-Maru research cruises of KH-12-4 (the North Pacific Ocean: from 23th August to 3rd October 2012) andKH-13-4 Leg. 4 (the Bay of Bengal: from 31th July to 14th August 2013), respectively. Major ionic concentrations (Na+ ,NH4 + , K+ , Mg2+ , Ca2+ , Cl− , NO3 − and SO4 2− ) in aerosol samples were determined by an ion chromatography after appropriate pretreatment. MF parameters were calculated as [X]eq /[total anion]eq (X: Cl− , NO3 − and nssSO4 2− ). Direct speciation of
Na in continental size-fractionated aerosol particles were conducted by XAFS spectroscopy on BL-10, SR-center, Ritsumeikan
University.
MF[Cl− ]eq was inversely correlated with both MF[NO3 − ]eq and MF[nssSO4 2− ]eq in continental coarse aerosol particles.
It can be said that the chlorine deficiency is explained by the reaction with NO3 − and/or nssSO4 2− . The regression line for
MF[Cl− ]eq -MF[nssSO4 2− ]eq was -2.16. As for MF[Cl− ]eq -MF[NO3 − ]eq , the regression line shows -1.03, and this regression
line satisfies the equation of y=1-x. Thus, HNO3 has large contribution as a reactant of NaCl in the urban atmosphere. Furthermore, chemical reaction of NaCl with HNO3 and H2 SO4 preferentially occur on the small aerosol particles because further
decrement of MF[Cl− ]eq was found in smaller size of aerosols compared with that of large aerosol particles. The speciation
analysis with XAFS spectroscopy showed comparable results with that obtained from MF analysis using the high reacted aerosol
samples from continent (MF[Cl− ]eq : MF[NO3 − ]eq : MF[nssSO4 2− ]eq =18:56:23). As for marine aerosol samples from theNorth Pacific Ocean, dominant reactant of NaCl is H2 SO4 . On the other hand, the reaction of NaCl occurs with both NO3 − andSO4 2− above the Bay of Bengal.
As a consequence, MF is very useful tools to find dominant reactant of NaCl and Na chemical species as a result of chlorine
deficiency in both continental and marine aerosol particles.

Keywords: atmospheric chemistry, aerosol, Na, XAFS spectroscopy

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