Yuichi Komazaki

Characterization of an Aerodyne Aerosol Mass Spectrometer (AMS): Intercomparison with other aerosol instruments

The Aerodyne Aerosol Mass Spectrometer (AMS) provides size-resolved chemical composition of non-refractory (vaporized at 600°C under vacuum) submicron aerosols with a time resolution of the order of minutes. Ambient measurements were performed in Tokyo between February 2003 and February 2004. We present intercomparisons of the AMS with a Particle-Into-Liquid Sampler combined with an Ion Chromatography analyzer (PILS-IC) and a Sunset Laboratory semi-continuous thermal-optical carbon analyzer. The temperature of the AMS inlet manifold was maintained at > 10 ˆ C above the ambient dew point to dry particles in the sample air (relative humidity (RH) in the inlet < 53%). Assuming a particle collection efficiency of 0.5 for the AMS, the mass concentrations of inorganic species (nitrate, sulfate, chloride, and ammonium) measured by the AMS agree with those measured by the PILS-IC to within 26%. The mass concentrations of organic compounds measured by the AMS correlate well with organic carbon (OC) mass measured by the Sunset Laboratory carbon analyzer (r 2 = 0.67–0.83). Assuming the same collection efficiency of 0.5 for the AMS organics, the linear regression slope is found to be 1.8 in summer and 1.6 in fall. These values are consistent with expected ratios of organic matter (OM) to OC in urban air.

Evolution of mixing state of black carbon particles : Aircraft measurements over the western Pacific in March 2004

0.63within12hours(h),namely2.3%h 1 ,afterbeingemitted from the Nagoya urban area in Japan. BC particles with a core diameter of 250 nm increased at the slower rate of 1.0% h 1 . The increase in coated BC particles was associated with increases in non-sea salt sulfate and water-soluble organic carbon by a factor of approximately two, indicating that these compounds contributed to the coating on the BC particles. These results give direct evidence that BC particles become internally mixed on a time scale of 12 h in urban plumes. Citation: Moteki, N., Y. Kondo, Y. Miyazaki, N. Takegawa, Y. Komazaki, G. Kurata, T. Shirai, D. R. Blake, T. Miyakawa, and M. Koike (2007), Evolution of mixing state of black carbon particles: Aircraft measurements over the western Pacific in March 2004,Geophys. Res. Lett., 34, L11803, doi:10.1029/2006GL028943.

Long‐range transport of ozone, carbon monoxide, and acidic trace gases at Oki Island, Japan, during PEM‐WEST B/PEACAMPOT B campaign

Ground based measurements of ozone, CO, HNO3 SO2, HCl, and formic acid were carried out at Oki, a remote island site in the Sea of Japan, during Feburuary 26 to March 16, 1994, as the Pacific Exploratory Mission in the Western Pacific/Perturbation by East Asian Continental Air Mass to the Pacific Oceanic Troposphere (PEM-West B/PEACAMPOT B) campaign. According to trajectory analysis, the air mass reaching Oki was classified into four groups: northerly, northwesterly, west-northwesterly, and westerly flows. Clear dependence of gas concentrations on flow direction of air mass was found for all species studied. Lowest concentrations were observed in the northerly airflow originating from the Bering Sea. The mean concentrations of ozone and CO in northerly flow were 37.6±1.9 and 151±1 ppbv, respectively. The mean values of HNO3, SO2, HCl, and formic acid in the northerly flow were 34±10, 41±5, 107±23, and 54±81 pptv, respectively. The highest concentrations of all species were observed in the westerly flow passing through a lower boundary layer over the Yellow Sea and South Korean Peninsula. The mean concentrations of ozone and CO in the westerly flow were 45.9±4.0 and 292±44 ppbv, respectively. The mean values of HNO3, SO2, HCl, and formic acid in the westerly flow were 137±37, 2075±1307, 515±214, and 264±183 pptv, respectively. Clear seasonal variation of the “background” concentrations of ozone and CO were identified by comparison with the data from the PEM-West A/PEACAMPOT A campaign conducted in the fall. In contrast to other species, strong diurnal variation of formic acid with a daytime maximum was observed. The possibility of photochemical formation of formic acid from HCHO and the HO2 radical is discussed.

Comparison of Black Carbon Mass Concentrations Observed by Multi-Angle Absorption Photometer (MAAP) and Continuous Soot-Monitoring System (COSMOS) on Fukue Island and in Tokyo, Japan

Reducing uncertainties associated with measurements of black carbon (BC) particles is critical for improved quantification of their impacts on climate and health. We compared BC measurements using a continuous soot-monitoring system (COSMOS) and a multi-angle absorption photometer (MAAP) to assess their uncertainties. We found that measurements by COSMOS and MAAP instruments correlate strongly to each other, and their hourly ratio showed minimal temporal variations, but the MAAP values were systematically higher by a factor of 1.56 ± 0.19 (1σ), based on simultaneous observations on Fukue, a remote island in Japan, for about a year. This factor was almost independent of the air mass origins and seasons. Measurements in central Tokyo for about 2 months also yielded a similar relationship, with a systematic difference factor of ∼1.8. It is likely that the systematic differences are caused by differences in the conditions/protocols in the thermal/optical BC determinations used for calibration of each optical instrument. Based on results from the COSMOS instrument calibrated using an elemental carbon and organic carbon analyzer with thermal/optical transmittance correction, the MAAP absorption cross section (6.6 m2 g−1) needs to be systematically increased to 10.3 m2 g−1 at 639 nm for Fukue when b abs values derived from the built-in software are used. Small temporal fluctuations in the ratios of MAAP-derived BC to COSMOS-derived BC were possibly caused by humidity effects and temporal variations in the optical properties of the measured particles. For MAAP, we also found that low filter-transmittance (0.2–0.5) could either increase or decrease the BC reading. The current best recommendations with the MAAP instrument are to use an increased cross section, to use data with high filter-transmittance (>0.5) only, and to control humidity. Copyright 2012 American Association for Aerosol Research

Transport of Atmospheric Pollutants from East Asia

Air-borne measurements of air pollutants transported from northeast Asia to Japan and the Pacific Ocean were carried out three times from 1996 to 1999 over the seas between Japan and Asian Continent. Those campaigns were named PEACAMPOT II under auspices of the IGAC/APARE program. A transport pattern of a highly polluted air mass from central China was found. Such air mass was driven by the quick movement of low pressure traveling from Taiwan area to the northeast of Japan. This finding supported well the results of modeling studies for long-range transport of atmospheric pollutants from East Asia.

Development of an automated measurement system using a diffusion scrubber and high-performance liquid chromatography for the monitoring of formaldehyde and acetaldehyde in automotive exhaust gas

An automated measurement system for monitoring formaldehyde (HCHO) and acetaldehyde (CH3CHO) in automotive exhaust gas by using a diffusion scrubber in combination with high-performance liquid chromatography (HPLC) was developed. HCHO and CH3CHO are effectively collected by the diffusion scrubber, which consists of a hydrophobic porous PTFE tube disposed concentrically within a Pyrex-glass tube and a scrubbing solution. 2,4-Dinitrophenylhydrazine is used as the scrubbing solution for trapping HCHO and CH3CHO, which are derivatized to formaldehyde 2,4-dinitrophenylhydrazone (DNPH-HCHO) and acetaldehyde 2,4-dinitrophenylhydrazone (DNPH-CH3CHO), respectively, with phosphoric acid as an acid catalyst. After the collection of the gas sample, the sample solution in the diffusion scrubber is injected into the HPLC system and DNPH-HCHO and DNPH-CH3CHO are separated and determined. All measurement operations are sequenced by a programmable controller and an automated continuous measurement can be performed at 10 min intervals. The collection efficiencies of HCHO and CH3CHO were higher than 97% at a gas flow rate of 0.21 min-1. The detection limit (3 sigma of the blank value) was 0.001 ppm v/v for HCHO and CH3CHO for a 1.61 gas sample volume. No interference of co-existing nitrogen dioxide (NO2) in the collection of HCHO and CH3CHO was observed. The average concentration of HCHO in the exhaust gas from methanol-fueled vehicles was 77.3 ppm v/v (n = 5) in the cold-phase mode when engines were first started. In the hot-phase mode, the average concentration of HCHO was 3.3 ppm v/v (n = 15). The concentrations of HCHO measured by this automated measurement system were in good agreement with those obtained using the impinger-HPLC method.

Laboratory measurements of emission factors of nonmethane volatile organic compounds from burning of Chinese crop residues

The emission factors (EFs) of nonmethane volatile organic compounds (NMVOCs) emitted during the burning of Chinese crop residue were investigated as a function of modified combustion efficiency in laboratory experiments. NMVOCs, including acetonitrile, aldehydes/ketones, furan, and aromatic hydrocarbons, were monitored by proton-transfer-reaction mass spectrometry. Rape plant was burned in dry conditions and wheat straw was burned in both wet and dry conditions to simulate the possible burning of damp crop residue in regions of high temperature and humidity. We compared the present data to field data reported by Kudo et al. (2014). Good agreement between field and laboratory data was obtained for aromatics under relatively more smoldering combustion of dry samples, but laboratory data were slightly overestimated compared to field data for oxygenated VOC (OVOC). When EFs from the burning of wet samples were investigated, the consistency between the field and laboratory data for OVOCs was stronger than for dry samples. This may be caused by residual moisture in crop residue that has been stockpiled in humid regions. Comparison of the wet laboratory data with field data suggests that Kudo et al. (2014) observed the biomass burning plumes under relatively more smoldering conditions in which approximately a few tens of percentages of burned fuel materials were wet.

A Chemical Ionization Mass Spectrometer for Ground-Based Measurements of Nitric Acid

Abstract A chemical ionization mass spectrometer (CIMS) instrument has been developed for high-precision measurements of gaseous nitric acid (HNO3) specifically under high- and variable-humidity conditions in the boundary layer. The instrument’s background signals (i.e., signals detected when HNO3-free air is measured), which depend on the humidity and HNO3 concentration of the sample air, are the most important factor affecting the limit of detection (LOD). A new system to provide HNO3-free air without changing both the humidity and the pressure of the sampled air was developed to measure the background level accurately. The detection limit was about 23 parts per trillion by volume (pptv) for 50-s averages. Field tests, including an intercomparison with the diffusion scrubber technique, were carried out at a surface site in Tokyo, Japan, in October 2003 and June 2004. A comparison between the measured concentrations of HNO3 and particulate nitrate indicated that the interference from particulate nitrate ...

Shipborne observations of atmospheric black carbon aerosol particles over the Arctic Ocean, Bering Sea, and North Pacific Ocean during September 2014

Measurements of refractory black carbon (rBC) aerosol particles using a highly sensitive online single particle soot photometer were performed on board the R/V Mirai during a cruise across the Arctic Ocean, Bering Sea, and North Pacific Ocean (31 August to 9 October 2014). The measured rBC mass concentrations over the Arctic Ocean in the latitudinal region > 70°N were in the range 0–66 ng/m3 for 1 min averages, with an overall mean value of 1.0 ± 1.2 ng/m3. Single-particle-based observations enabled the measurement of such low rBC mass concentrations. The effects of long-range transport from continents to the Arctic Ocean were limited during the observed period, which suggests that the low rBC concentration levels would prevail over the Arctic Ocean. An analysis of rBC mixing states showed that particles with a nonshell/noncore structure made a significant contribution to the rBC particles detected over the Arctic Ocean.

Seasonal cycles of ozone and oxidized nitrogen species in northeast Asia 2. A model analysis of the roles of chemistry and transport: OZONE AND SPECIATED NOyIN A GLOBAL CTM

Received 13 November 2001; revised 18 May 2002; accepted 20 May 2002; published 11 December 2002. [1] The dominant factors controlling the seasonal variations of ozone (O3) and three major oxidized nitrogen species, peroxyacetyl nitrate (PAN), nitrogen oxides (NOx), and nitric acid (HNO3), in northeast Asia are investigated by using a three-dimensional global chemical transport model to analyze surface observations made at Rishiri Island, a remote island in northern Japan. The model was evaluated by comparing with observed seasonal variations, and with the relationships between O3, CO, and PAN. We show that the model reproduces the chemical environment at Rishiri Island reasonably well, and that the seasonal cycles of O3, CO, NOy species, and VOCs are well predicted. The impact of local emissions on some of these constituents is significant, but is not the dominant factor affecting the seasonal cycles. The seasonal roles of chemistry and transport in controlling O3 and PAN are revealed by examining production/destruction and import/ export/deposition fluxes in the boundary layer over the Rishiri region. For O3, transport plays a key role throughout the year, and the regional photochemical contribution is at most 10% in summer. For PAN, in contrast, transport dominates in winter, while in-situ chemistry contributes as much as 75% in summer. It is suggested that the relative contribution of transport and in-situ chemistry is significantly different for O3 and PAN, but that the wintertime dominance of transport due to the long chemical lifetimes of these species is sufficient to drive the seasonal cycles of springtime maximum and summertime minimum characteristic of remote sites. INDEX TERMS: 0345 Atmospheric Composition and Structure: Pollution—urban and regional (0305); 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0368 Atmospheric Composition and Structure: Troposphere— constituent transport and chemistry; 9320 Information Related to Geographic Region: Asia; KEYWORDS: tropospheric ozone, oxidized nitrogen, seasonal cycle, transport, photochemistry Citation: Tanimoto, H., O. Wild, S. Kato, H. Furutani, Y. Makide, Y. Komazaki, S. Hashimoto, S. Tanaka, and H. Akimoto, Seasonal cycles of ozone and oxidized nitrogen species in northeast Asia, 2, A model analysis of the roles of chemistry and transport, J. Geophys. Res., 107(D23), 4706, doi:10.1029/2001JD001497, 2002.