The concentration of suspended particulate matter smaller than 2.5 µm (PM2.5) was linearly correlated with the column aerosol optical thickness (AOT) based on simultaneous measurements at a NASA/AERONET station at Kinki University Campus, Higashi-Osaka, Japan, between March 2004 and June 2006. The correlation coefficient differed with the aerosol type, being maximal when PM2.5 values were measured 120 minutes after AOT data for a dust episode, but almost independent of the time difference between measurements for anthropogenic aerosols. The obtained results were validated using data obtained at the Higashi-Osaka and Noto sites. Our results suggest that the PM2.5 mass concentration can be estimated from the AOT, and vice versa, and hence a distribution map of PM2.5 can be produced from the satellite-derived AOT map determined from the Aqua/MODIS sensor.
Green house gases observational satellite (GOSAT) was successfully launched on 23 January in 2009 by JAXA. The
satellite carries two sensors, Fourier Transform Spectrometer (FTS) and Cloud Aerosol Imager (CAI). The CAI has four
observing wavelengths as 0.38, 0.67, 0.87 and 1.6 μm. It is shown here that this CAI/0.38μm is a unique observing band
among usual sensors as MODIS and so on, and it is useful to distinguish the aerosol characteristics of absorbing (e.g.,
biomass burning) or non-absorbing (e.g., sulfate). In other word, this work proposed a space based retrieval algorithm
for atmospheric aerosols including estimation of the optical constant for biomass burning particles. Our algorithm aims
to apply the combination use of near UV data with GOAT/CAI, the violet data with Aqua/MODIS and near-IR
polarization data with PARASOL/POLDER. In practice the algorithm has been partly examined by using ADEOS-2 /
GLI data.
It is well known that the heavy soil dust has been transported from the China continent to Japan on westerly winds,
especially in spring. It is also known that the increasing emissions of anthropogenic aerosols associated with continuing
economic growth in Asia has caused serious air pollution over the wide range of East Asia. Accordingly the dust
particles involve anthropogenic aerosols as well as soil dust. Thus aerosols in Asia are very complex due to mixing of
small anthropogenic particles and large dust particles, which are called Asian dust. The satellite observation is an
effective tool for global monitoring of the Asian dust. A new algorithm for detection of Asian dust from space is
proposed based on the multispectral satellite (Terra/Aqua/MODIS) data. The derived space-based results are validated
with the ground-based measurements and/or model simulations. The sun/sky photometry has been undertaken at
NASA/AERONET stations at Higashi-Osaka in Japan, where the suspended particulate matter (SPM) sampling and
NIES/LIDAR network equipment have been simultaneously working. In order to validate the satellite results with these
surface-level data, an aerosol transportation model is available. In other word, the space-based and/or surface-based
measurements are examined with the model simulations, and vice-versa.
KEYWORDS: Aerosols, Atmospheric modeling, Data modeling, MODIS, Solar radiation models, 3D modeling, Combustion, Atmospheric particles, Satellites, Solar radiation
A wide variety of aerosols are suspended in the atmosphere. Especially in East Asia, a huge amount of fossil fuel burning
aerosols are emitted throughout the year. Further it seems that the characteristics of aerosols change with the season, and
hence the influence impact of aerosols over the climate also varies according to the season. Thus an accurate estimation
of seasonal aerosol properties is an urgent subject on the global climate problem. This work is based on the
Moderate-resolution Imaging Spectroradiometer (MODIS) data and the simulation results with a three-dimensional
aerosol transport-radiation model. It is of interest to mention that aerosol distribution explicitly shows the seasonal
change. For example, aerosol concentration in summer is larger than that in winter from eastern China to Japan. This
result is drawn from both MODIS data and model simulations. The model simulations suggest that the seasonal change is
due to the variations in the photochemical reaction process and transportation process. MODIS data shows that the
sulfate aerosols are much more dominant in summer than those in winter at Beijing which is influenced strongly by fossil
fuel burning aerosols. This fact is also supported by model simulations. From the present study I can draw such a result
in respect of surface radiation budget as the aerosol impact on the reduction of solar radiation is more dominant in
summer than that in winter in East Asia.
Concentration of suspended particulate matter less than 2.5 μm (PM2.5) is a representative parameter of air quality.
Simultaneous measurements of PM2.5 and the column aerosol optical thickness (AOT) have been performed at a
NASA/AERONET station, Higashi-Osaka, Japan since March 2004. They successfully provide a linear correlation
between PM2.5 and AOT. A Mie scattering lidar instrument was deployed at the same observational site in April, 2008.
It provides us with the attenuated backscattering coefficients of aerosols at wavelengths of 0.532 and 1.064 μm, which
indicate the vertical distribution of aerosols. This work intends to improve the correlation between AOT and PM2.5 by
using the measurements of lidar.
The retrieval algorithm for aerosol remote sensing has still some problems to be solved. For example, miss-leading of
aerosol type selection has often happened due to the difficulties to detect the absorbing aerosols, such as carbonaceous
and dust aerosols, over land. The POLDER polarization data are useful to estimate the aerosol information even over
land region. This work intends to modify the satellite retrieval procedure by combining the model simulations. The
result of numerical simulations is used as a priori information of existence of absorbing aerosols in the atmosphere. Our
procedure, in practice, is applied to the POLDER observation period in April, 1997. As results, aerosol optical thickness
at three wavelengths are retrieved, and then they are applied to estimate the mass concentration of fine mode aerosols
based on the relationship between AOT by ground based sun photometry and PM2.5 sampling. It is found that in April of
1997 the bio-mass burning aerosols are heavily loaded over South East Asia.
The relationship between concentration of suspended particulate matter (PM2.5) and column aerosol optical thickness
(AOT) is examined based on the simultaneous measurements at a NASA/AERONET station at Kinki University
Campus, Higashi-Osaka, Japan since March in 2004. We drew the following results:
1. A strong linear correlation exists between PM2.5 and AOT,
2. The correlation is better within each type of aerosols as anthropogenic type and dust type than overall,
3. The correlation coefficients take the highest value in such a case that PM2.5 values are measured in 30-minutes
behind after AOT data.
These facts are explained with the model simulations. Our results highlight the possibility that the PM2.5 concentration
can be estimated from the AOT, and vice versa. Moreover, combining radiometric aerosol information with surfacelevel
particulate mass data appears to be a promising approach for gaining a better understanding of air quality and the
atmospheric environment.
The aerosol properties of urban atmospheric particles have been analyzed for radiometry data obtained using a multi-spectral photometer located at a NASA/AERONET station at Kinki University Campus, Higashi-Osaka, Japan, since 2002. The suspended particulate matter has been simultaneously measured at the same AERONET site since 2004. Our measurements and a clustering analysis reveal the aerosol types over the industrial city of Higashi-Osaka. It is shown that aerosols at Higashi-Osaka can be classified into three categories: (1) ordinary, which represents the background clear atmosphere of Higashi-Osaka, (2) anthropogenic aerosol events, and (2) dust episodes called Kosa, when large amounts of soil dust are transported to Higashi-Osaka from the Chinese mainland on westerly winds, especially in spring. We also found that the linear correlation exists between column aerosol optical thickness and PM2.5 concentration, and the correlation is better within each aerosol cluster than overall.
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