Susumu Tohno

Wavelength‐dependent aerosol single‐scattering albedo: Measurements and model calculations for a coastal site near the Sea of Japan during ACE‐Asia

Wavelength-dependent optical properties together with the size-resolved elemental and chemical composition of the atmospheric aerosol were measured at Yasaka, Japan, near Wakasa Bay on the coast of the Sea of Japan. Observations were performed as part of the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) campaign during three weeks in March and April 2001. Information about the detailed chemical composition and the size distribution of the aerosol, including absorbing material, was used to model optical properties of the aerosol and compare them with directly measured properties. Continuous, size-resolved measurements of aerosol scattering and backscattering coefficients were made at wavelengths of 450, 550, and 700 nm. Aerosol size distribution measurements were taken three times during the campaign for a period of 3-4 days each, using cascade impactors. One of the measurement periods was influenced by an intense yellow dust event originating on the Asian continent (20-25 March 2001), while the other two data sets were only weakly influenced by dust particles. The size-resolved measurement of aerosol scattering coefficients and the chemical analysis showed that the dust was accompanied by fine accumulation-mode particles during the dust event. The effects of the mineral dust particles on the optical and chemical properties of the aerosol are discussed, and data sets with and without desert dust influence are compared. Before the optical closure calculation a mass closure of the aerosol was performed, and the influence of the nonanalyzed fraction on the calculated optical properties of the aerosol is investigated. In general, good agreement between measured and modeled aerosol optical properties was found for the aerosol scattering and absorption coefficients, while less agreement was found for the backscattering coefficients, especially for the coarse mode of the aerosol. A distinct difference between the dust and nondust periods was found for the wavelength-dependent single-scattering albedo.

Life-cycle analysis of charging infrastructure for electric vehicles

Life-cycle analysis of a charging station for electric vehicles (EVs) was performed in the three phases, that is, production, transportation and installation of the charging equipment, which consists of charger, battery and stand. We chose parking lots on expressways, commercial parking lots in cities, municipal facilities, shopping centers, etc. throughout the country as the charging sites according to the EV charge program in Southern California. Air-pollutant emissions during the transportation phase were calculated based on the emission factors of vehicles, running speed and the transport distance between one factory of the charging equipment and each site. The share of transporting the charging machines in total emissions of CO2, SOx and CO was less than 15% and the production phase was dominant. In case of NOx, the share of transporting them was over 20%. The relation between gasoline vehicle and gas station was applied to estimate the number of EVs using the charging stations through the country, and the contribution of the charging stations to life-cycle emissions of air pollutants from EV was presented. The share of infrastructure in total emissions of CO2 was 16% in our model case. Thus the development of the charging infrastructure almost did not change the advantage of EV compared to gasoline vehicle (GV) in terms of CO2, NOx, and CO emissions. But an EV emits more life-cycle SOx than gasoline vehicles (GVs).

Characterization of the winter atmospheric aerosols in Kyoto and Seoul using PIXE, EAS and IC

Abstract Characteristics of atmospheric aerosols in Kyoto, Japan and Seoul, Korea were investigated using particle-induced X-ray emission (PIXE), elemental analysis system (EAS) and ion chromatograph (IC). Atmospheric aerosols were collected into fine and coarse fractions using a two-stage filter pack sampler in Kyoto and Seoul in winter of 1998. PIXE was applied to analyze the middle and heavy elements with atomic number greater than 14 (Si), and EAS was applied to analyze the light elements such as H, C and N. The total mass concentration in Seoul was about two times higher than in Kyoto and the concentration of Ca, Si, and Ti that are mainly originated from soil were remarkably higher in Seoul. During an Asian dust storm event, the concentration of soil components increased dramatically and amounted to about 15 times higher than average concentration. The fine/coarse ratios of NH4+, NO3−, and SO42− were extremely high in both sites. The fact that nearly 70% of fine particles in both Kyoto and Seoul consist of the light elements (N, C, and H) suggests the importance of light elements measurement. Good mass closure for fine particles with light element data was achieved.

Changes in the Carbon Footprint of Japanese Households in an Aging Society

As the aging and low birthrate trends continue in Japan, and as changes in the working population and consumption patterns occur, new factors are expected to have an impact on consumption-based greenhouse gas (GHG) emissions. We present the impacts of changes in the composition of Japanese households on GHG emission structures using current (2005) consumption-based accounting on the commodity sectors that are expected to require priority efforts for reducing emissions in 2035. This is done using the Global Link Input-Output model (GLIO) and domestic household consumption data and assuming that recent detailed consumption expenditures based on the Social Accounting Matrix (SAM) will continue into the future. The results show that consumption-based GHG emissions derived from Japanese household consumption in 2035 are estimated to be 1061 Mt-CO2eq (4.2% lower than in 2005). This study can be used to reveal more information and as a resource in developing policies to more meticulously and efficiently reduce emissions based on emission and import rates for each domestic and overseas commodity supply chain.

Effects of electric vehicles (EV) on environmental loads with consideration of regional differences of electric power generation and charging characteristic of EV users in Japan

In order to evaluate the reduction effect of electric vehicles (EVs) on various atmospheric environmental loads, we have performed a life-cycle inventory analysis (LCI), including the installation of charging stations and regional, seasonal and temporal difference of the energy mix of electricity generation. For an EV converted from a small gasoline vehicle, a regional LCI analysis was carried out in the following steps: (1) location of the charging stations, (2) modeling of charging characteristics of station users, (3) calculation of temporal life-cycle emission intensities of CO2, NOx and SOx by region, season and day. Assuming that total traveling distance is 100,000 km, the electricity consumption rate is 0.119 kWh/km and the charging/discharging efficiency is 70%, the average life-cycle emission of CO2 for that EV was 3.6 t-C throughout Japan. However, if we took regional difference into account, the emission ranged over 70-160% of the average amount. It was revealed that the regional difference of the primary energy mix significantly affected the emissions of EVs during the operation phase.

Production of highly concentrated nanophase Ag dispersoids without aggregation

High-number-density, contact-free nanophase silver particles were prepared in hexane. The particles were produced by an evaporation/condensation aerosol process, trapped in an organic solvent, coated with a surfactant, and then concentrated. A highly concentrated state (1018–1019 particles m−3) could be achieved in hexane for particles with 7 nm mean diameter. The changes in particle size and agglomeration during processing were determined from electron microscopy and photon correlation spectroscopy. The surfactant coating of the particle surface effectively prevented fusion of the nanophase particles. The advantage of this method was confirmed by the size preservation of the particle size distribution after deflocculation from the coagulums which had formed upon concentrating the solution.

Fixation and chemical analysis of single fog and rain droplets

Abstract Last decade, the importance of global environmental problems has been recognized worldwide. Acid rain is one of the most important global environmental problems as well as the global warming. The grasp of physical and chemical properties of fog and rain droplets is essential to make clear the physical and chemical processes of acid rain and also their effects on forests, materials and ecosystems. We examined the physical and chemical properties of single fog and raindrops by applying fixation technique. The sampling method and treatment procedure to fix the liquid droplets as a solid particle were investigated. Small liquid particles like fog droplet could be easily fixed within few minutes by exposure to cyanoacrylate vapor. The large liquid particles like raindrops were also fixed successively, but some of them were not perfect. Freezing method was applied to fix the large raindrops. Frozen liquid particles existed stably by exposure to cyanoacrylate vapor after freezing. The particle size measurement and the elemental analysis of the fixed particle were performed in individual base using microscope, and SEX-EDX, particle-induced X-ray emission (PIXE) and micro-PIXE analyses, respectively. The concentration in raindrops was dependent upon the droplet size and the elapsed time from the beginning of rainfall.

Morphological and dynamic characterization of Pb fume particles undergoing Brownian coagulation

Morphological changes of Pb fume particles undergoing Brownian coagulation in a flowing system were studied using computer image processing of two-dimensional electron micrographs to measure radii of gyration and perimeters. From these two parameters; (1) fractal dimensions were calculated considering the aggregates as multifractal; changes in fractal dimension were related to the degree of agglomeration; (2) volume equivalent diameters were calculated based on a new relationship between volume and projected area for fractal aggregates, presented in Appendix A. The validity of this equation was confirmed for aggregates composed of small numbers of primary particles (n < 30); and (3) dynamic shape factors were calculated and comparison was made with a new relationship between shape factor and volume equivalent diameter presented in Appendix B.

Comprehensive assessment of PM2.5 physicochemical properties during the Southeast Asia dry season (southwest monsoon)

A comprehensive assessment of fine particulate matter (PM2.5) compositions during the Southeast Asia dry season is presented. Samples of PM2.5 were collected between 24 June and 14 September 2014 using a high-volume sampler. Water-soluble ions, trace species, rare earth elements, and a range of elemental carbon (EC) and organic carbon were analyzed. The characterization and source apportionment of PM2.5 were investigated. The results showed that the 24 h PM2.5 concentration ranged from 6.64 to 68.2 µg m−3. Meteorological driving factors strongly governed the diurnal concentration of aerosol, while the traffic in the morning and evening rush hours coincided with higher levels of CO and NO2. The correlation analysis for non sea-salt K+-EC showed that EC is potentially associated with biomass burning events, while the formation of secondary organic carbon had a moderate association with motor vehicle emissions. Positive matrix factorization (PMF) version 5.0 identified the sources of PM2.5: (i) biomass burning coupled with sea salt [I] (7%), (ii) aged sea salt and mixed industrial emissions (5%), (iii) road dust and fuel oil combustion (7%), (iv) coal-fired combustion (25%), (v) mineral dust (8%), (vi) secondary inorganic aerosol (SIA) coupled with F− (15%), and (vii) motor vehicle emissions coupled with sea salt [II] (24%). Motor vehicle emissions, SIA, and coal-fired power plant are the predominant sources contributing to PM2.5. The response of the potential source contribution function and Hybrid Single-Particle Lagrangian Integrated Trajectory backward trajectory model suggest that the outline of source regions were consistent to the sources by PMF 5.0.

An Aerosol climatology at Kyoto: Observed local radiative forcing and columnar optical properties

Abstract In order to evaluate the radiative effect of the atmospheric aerosol at Kyoto, Japan, surface solar irradiance and columnar aerosol optical properties were observed in the period between September 1998 and December 2001. The aerosol optical thickness, which is an indicator of the columnar mass burden and the overall radiative effect of the aerosol, was on average 0.27 at a wavelength of 500 nm. Springtime aerosol optical thickness was generally higher primarily because of “yellow dust” from the Asian continent. The Angstrom exponent had values ranging from 0.5 to 2.8, with an average value of 1.64, and was found to be low in periods during which the aerosol optical thickness was high. As a first step toward calculating the local climate impact of the atmospheric aerosol at Kyoto, the clear-sky direct radiative forcing is considered in this paper. For an evaluation of the surface aerosol radiative forcing, observed total surface fluxes measured by a pyranometer are subtracted from modeled surface ...