Japan Meteorological Agency (JMA) continuously monitors the aerosol optical depth (AOD) at three stations in Japan. Until the year 2006 sunphotometers (Model MS110, manufactured by EKO Instruments, Japan) had been used to measure AOD. Since the year 2007 precision filter radiometers(PFR, available from Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center, PMOD/WRC) has been used to monitor AOD following recommendations by World Meteorological Organization (WMO). WMO encourages that the calibration constant over an interval of one year and the uncertainty of measured AOD are less than 2% and 0.02, respectively. In order to verify that WMO’s recommendations are being satisfied our sunphotometers were calibrated by Langley method. For the same purpose our PFR instruments are sent to PMOD/WRC periodically to determine the extraterrestrial calibration constants of each PFR instruments.
Data quality assurance of lidar observations of aerosols is discussed. Measurement principles of Mie scattering lidar, Raman lidar and high-spectral resolution lidar are introduced, and errors in the measured parameters and the derived parameters are discussed. The data processing methods and data products for the two-wavelength (532 nm and 1064 nm) polarization-sensitive (532 nm) lidars in the Asian dust and aerosol lidar observation network (AD-Net) are presented. It is concluded that clear definitions of data products and providing the data along with error estimates are essential for the use of the data. Possibility of establishing consistency of observations with lidars having different measurement parameters based on a unified data analysis method (the aerosol component analysis method) is also discussed.
Aerosol particles acting as cloud condensation nuclei (CCN) determine initial cloud droplet concentrations and subsequent evolutions of microphysical structures of clouds and precipitation, and affect a short-range precipitation forecast and climate change projection. The Global Atmosphere Watch Scientific Advisory Group recommends the CCN monitoring as a part of determination of the spatio-temporal distribution of aerosol properties related to climate forcing and air quality on multi decadal time scales and on regional, hemispheric and global spatial scales. We have been monitoring CCN concentrations along with aerosol concentrations, aerosol size distributions, and ice nuclei (IN) concentrations on the campus of Meteorological Research Institute in Tsukuba city (36.06°N,140.13°E), Ibaraki, Japan since March 2012. In this report, the maintenance information for long-term measurements with continuous-flow stream-wise thermal gradient chamber type CCN counter, especially calibration methods of supersaturations in the CCN counter and their error factors, are described. Also, the results of the long-term monitoring of CCN concentrations and the research activity on cloud droplet formation processes at MRI are briefly introduced.
Sulfate aerosols are ubiquitous in the troposphere and play important roles in air pollution and climate change. This article reviews the current status of automated, online analysis methods for mass concentrations of PM2.5 sulfate aerosols. The methods include a Particle-Into-Liquid sampler coupled with ion chromatography (PILS-IC), an Aerodyne aerosol mass spectrometer (AMS), a Thermo sulfate particle analyzer (SPA). Although they can achieve sufficiently high precision required for ambient measurements in many cases, routine calibration is one of the most critical issues that have not been fully addressed. A calibration protocol for the quality assurance of online analysis of mass concentrations of PM2.5 sulfate aerosols is proposed and discussed.
In a “task and ambient air-cleaning system”, there is no ceiling, and therefore equipment apparatus such as fan coil unit, fan filter unit and air duct are exposed to the surroundings. Consequently, reentrainment of particles deposited on those equipment becomes a problem. In this paper, we examined the reentrainment of particles which were deposited on fan coil unit, fan filter unit and air duct by airflow of a cleanroom. Test pieces (aluminum plate or polyvinyl chloride plate) on which particles (glass beads, Lycopodium, or airborne particulate matter) were deposited were placed in a wind tunnel, clean air was supplied to the tunnel, and the reentrained particles were measured by a particle counter. As a result, it was found that the deposited particles were resuspended at an air velocity of about 3.5 m/s or higher and that the particles were hardly resuspnded at the air velocity (0.3–0.4 m/sec) in a cleanroom.
We conducted intensive field studies in Bangi, Selangor, Malaysia in September, 2013 and characterized PM2.5 inorganic ions based on ground-based sampling. Inorganic ions in PM2.5 were primarily composed of sulfate ion (66% of total ions mass), and particulate sulfate was considered to be present in the form of mixtures of ammonium (61%), potassium (24%), and sodium sulfates (15%) in the atmosphere.Extremely strong chlorine loss from sodium and potassium chloride particles was suggested.
When we consider the health effect of PM2.5, the size distribution of inhaled particle is the important factor as well as the concentration and the chemical component. The size distribution significantly alters the total and regional deposition in the respiratory tracts. However, regulations of PM2.5 are based on the mass concentration (μg m-3) without mentioning the particle size and components. In this report, Ipresent the importance of particle size using ICRP Publ.66 respiratory tract model for dose assessment of inhaled radioactive particles through the discussion on the relationship between particle size of PM2.5and regional deposition in the respiratory tracts.