The atmospheric aerosol distribution in Asia is complex because it is influenced by both natural phenomena and human activities. In this article, multifaceted approach using satellite observations and numerical model simulation shows seasonal and regional variations of the aerosol distribution over Asia. Asia covers a large area however, this article is limited to East and Southeast Asia. The aerosol optical thickness (AOT) in the inland desert area is normally high in spring and dusty aerosols are widely spread with the wind. The AOT values are high in summer over East Asia. A high AOT caused by biomass burning plumes is observed in autumn over Southeast Asia and in spring over Siberia and heavy air pollution occurs in Beijing in winter, a very well-known phenomenon. These phenomena caused by heavy aerosol concentration were determined based on Aqua/MODIS data and aerosol characteristics retrievals and estimated the aerosol characteristics. Furthermore, the impact of aerosols on the climate assessed by numerical model simulations suggest that aerosols reduce solar radiation and therefore the Earth's surface temperature. In addition to these influences on the radiation budget, aerosols have a significant potential to change the circulation fields.

It is known that the biomass burning aerosols (BBA) generated by the large-scale forest fires and burn agriculture have influenced the severity of air pollution. Nevertheless the biomass burning plumes increase due to global warming and climate change and vice versa. It is worth noting that the near ultra violet (NUV) measurements are helpful for the detection of carbonaceous particles, which are the main component of aerosols from biomass burning. In this work, improved retrieval algorithms for BBA are interpreted by using the measurements observed by GLI and POLDER-2 on Japanese short term mission ADEOS-2 from December 2002 to October 2003. The GLI sensor has 380nm channel. Finally the obtained optical properties of BBA are investigated from the standpoint of spatial and temporal variations in comparison with the numerical model simulations.

This work intends to consider the retrieval algorithms of remote sensing for severe air pollutions. In these cases mixture of aerosols and clouds, namely aerosols in cloudy scenes and/or clouds in heavy aerosol episode, are often occurred. Aerosol retrieval in the hazy atmosphere has been achieved based on radiation simulation method of successive order of scattering (MSOS). JAXA has been developing the new Earth observing system GCOM-C satellite. GCOM-C will be launched in early of 2017 and board the polarization sensor SGLI. The SGLI has multi (19)-channels as MODIS and measures polarized reflected sunlight at wavelengths of 0.679 mu m and 0.869 mu m as POLDER. The radiance and polarization degree are taken into account here in the severe biomass burning episode over Borneo islands in Indonesia observed by PARASOL. / POLDER and Aqua/MODIS. As a result the possibility of JAXA / GCOM-C / SGLI related to remote sensing for a mixture case of aerosols and clouds can be examined.

Aerosol distributions in East Asia are complicated owing to both natural factors and human activities. In recent years, influence of yellow sand and biomass burning aerosols generated by agricultural biomass burning (ABB) has been noted upon the severe air pollution episodes. This work intends to make the retrieval algorithm more efficient and to make the aerosol model more tractable as far as heavy air pollution caused by ABB is concerned. Aerosol retrieval in the hazy atmosphere is achieved based on radiation simulation method of successive order of scattering (MSOS) for the moderate resolution imaging spectroradiometer (MODIS) on AQUA data. The retrieved aerosol properties agree well with the ground measurements and numerical model simulations. Multi-angle observations with the polarization and directionality of the Earth's reflectances (POLDER) on the polarization & anisotropy of reflectances for atmospheric sciences coupled with observations from a lidar (PARASOL) are available for aerosol retrieval from a mixture of cloud and haze, and many potential applications of MSOS involving polarization information are expected to be available for cloud as well as aerosol episodes.

We investigate heavy haze episodes (with dense concentrations of atmospheric aerosols) occurring around Beijing in June, when serious air pollution was detected by both satellite and ground measurements. Aerosol retrieval is achieved by radiative transfer simulation in an Earth atmosphere model. We solve the radiative transfer problem in the case of haze episodes by successive order of scattering. We conclude that air pollution around Beijing in June is mainly due to increased emissions of anthropogenic aerosols and that carbonaceous aerosols from agriculture biomass burning in Southeast Asia also contribute to pollution.

Aerosol retrieval work from satellite data is divided into three parts: satellite data analysis, aerosol modeling, and multiple light scattering simulations in the atmosphere modeling what is known as the radiative transfer problem. It is well known that the aerosol model has been developed using the accumulated measurements during more than ten years provided with the world-wide aerosol monitoring network (AERONET). The radiative transfer simulations incorporate the Rayleigh scattering by molecules and Mie scattering by aerosols in the atmosphere. Thus the aerosol properties are estimated by comparing satellite measurements with the numerical values of radiation simulations in the Earth-atmosphere model. It is reasonable to consider that the precise simulation of multiple light scattering processes is necessary, and requires a long computational time, especially for an optically thick atmosphere. Therefore, efficient algorithms for radiative transfer problems are indispensable to retrieve aerosols from space. It is shown here that dense aerosol events can be well simulated by a semi infinite radiative-transfer model. For an example, the air pollution event observed by Aqua/MODIS in June of 2010 over Beijing is interpreted based on the proposed aerosol models and the semi-infinite radiative transfer simulation code known as MSOS (Method of Successive Order of Scattering).

Air pollution in East Asia has become severe in recent years, with heavy air pollutants and Asian dust being transported from China to neighboring countries throughout the year. In this study, we focus on heavy haze event occurring around Beijing in June, when a serious aerosol episode was detected by both satellite and ground measurements. Retrieval of atmospheric aerosol characteristics from satellite is achieved by radiative transfer simulation in the Earth atmosphere model. The aerosol model is compiled from the worldwide aerosol monitoring network (NASA/AERONET). It is shown here that the radiative transfer problem in the case of aerosol episode is solved by a method of successive order of scattering. In addition we conclude that air pollution around Beijing in June is mainly due to increasing emissions of the anthropogenic aerosols, furthermore carbonaceous aerosols from agriculture biomass burning in Southeast Asia also contribute to the pollution.

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 surface-level particulate mass data appears to be a promising approach for gaining a better understanding of air quality and the atmospheric environment.

To monitor urban atmospheric particles, we have undertaken simultaneous measurements of aerosols and suspended particulate matter (SPM) at Kinki University Campus, Higashi-Osaka, Japan, since 2004. The largest dust event recorded during our long-term observations was detected during the spring of 2006.
We also examined the relationship between PM_2.5 concentrations and aerosol properties obtained from radiometry using a multi-spectral photometer located at a NASA/AERONET station. We found a linear correlation between aerosol optical thickness and PM_2.5 concentrations for both ordinary days and days with dust events.

For monitoring of urban atmospheric particles, simultaneous measurements of aerosols and suspended particulate matter (SPM) have been undertaken at Kinki University Campus, Higashi-Osaka, Japan, since 2004. The relationship between PM2.5 concentrations and aerosol properties obtained from radiometry using a multi-spectral photometer located as a NASA/AERONET station is examined in this work. It is found a linear correlation between aerosol optical thickness and PM2.5 concentrations for both ordinary days and days with dust events. This fact indicates that aerosol characteristics can be estimated from SPM data, and vice versa. Combining radiometric aerosol information with surface-level particulate mass measurements is useful in studying air quality and aerosol properties. It is of interest to mention that the largest dust event recorded among our long-term observations was detected during the spring of 2006.

Each retrieval algorithm for atmospheric aerosols, clouds and water vapor from ADEOS/POLDER data is described. A POLDER sensor, mounted on the Earth observation satellite ADEOS in 1996, is a unique sensor which can gather multi-directional (up to 14) polarization measurements of one target. Atmospheric aerosol properties as optical thickness and Angstrom exponent are derived from the POLDER polarization data at wavelengths of 0.670 and 0.865 mum. The polarization data at 0.865 mum is also available for cloud retrieval. Two channels in the near infrared wavelengths are used to estimate the total column water vapor content. The first channel is in the water vapor absorption band of 0.910 mum and the second is in the gas absorption-free band of 0.865 mum. In practice, a ratio of each reflectance for these two channels is used in this study. Then the obtained global maps of aerosol properties, cloud microphysics and water vapor content are compared with one another. It is shown that column number density of aerosols has a negative correlation with the effective radius of cloud particles and proportionally correlates with the optical thickness and the column number density of cloud particles. These results confirm the indirect effect of aerosols, namely aerosols play sufficient role as cloud condensation nuclei (CCN). (C) 2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

In this work we describe procedures for detection of clouds and water/ice discrimination of the cloud top using the combined information of the polarization data from ADEOS/POLDER (0.865μm) and the infrared data from OCTS (10.9μm). On the basis of the satellite images obtained on November 10, 1996, we show that the cloud detection algorithm for POLDER proposed by CNES tends to overestimate the cloud regions. Better estimation can be obtained by adding a brightness temperature test by means of the OCTS data. A single-scattering simulation, carried out for water droplets and hexagonal ice crystals, indicates that the phase discrimination of the cloud top can be accomplished by comparing the polarized reflection data of POLDER at two scattering angles of 100^°and 140^°. The result is in reasonable agreement with the classification with the OCTS temperature data.

衛星データを用いた雲特性の導出方法について報告した。 （英文）

This study aimed at performance of efficient system for aerosol retrieval based on the satellite data utilized together with ground-based measurements, radiative transfer algorithms, and the numerical model simulations. Summary of this work is as follows: Improved description of aerosol models, and validation it by using Terra/MODIS and ADEOS-2/GLI. 2. Development of radiative transfer system for polarization or non-polarization field. 3. An absorbing aerosol index (AAI) has been proposed defined as the ratio of the satellite-observed radiance at a wavelength of 412 nm to that at 380 nm in order to detect the absorbing particles. 4. Application for air pollution, PM analysis and an impact on the environment and climate change. 5. Validation system for satellite observations based on NASA/AERONET data. 6. The obtained results in this study are available for JAXA/GCOM-C/SGLI and other future missions.

(1)NASA/AERONET放射計等による大気エアロゾル地上観測、(2)SPMのサンプリング計測と化学分析、(3)エアロゾル放射特性とSPM値の関係解析、(4)地上と衛星データの併合によるエアロゾルマップの導出等に関し、継続的に研究実績を挙げている. (5)2008年5月にNIESライダーネットワーク機器を設置し、(6)エアロゾルの発生から拡散までの解明、(7)総合的なデータ解析手法の実装、(8)モデルシミュレーションと実データの融合を実現した.

The obtained results during this search period from 2001 to 2004 are as follows ; 1.Aerosol retrieval using satellite data The global distribution of aerosols are obtained by using polarization data together with radiance data derived from ADEOS/POLDER in 1997 and 2003. The basic idea of our aerosol retrieval is that the scattering behavior of aerosols plays a sufficient role in the polarization field of the Earth atmosphere-surface system in the near infrared wavelengths. It is shown that the aerosol loading increases from 1997 to 2003, and aerosol events, which means anomaly lots of aerosol loading, are shown in north-west Africa and east Asia. 2.Ground based photo-polarimetry of aerosols To characterize urban aerosols, sun/sky photometry and polarimetry with PSR-1000 (Opto Research) have been performed over Higashi-Osaka since 1996. Multi-spectral photometer CE-318-2 (Cimel Electronique) was subsequently set up for an AERONET site in 2002. Another AERONET instrument (CE-318-1) has been operating at Shirahama since 2000 as a part of NASA/AERONET. The radiometers at both Osaka and Shirahama were calibrated using a standard AERONET procedure. The new SPM-613D instrument makes it possible to determine the relationship between aerosol properties and the particulate mass

平成15年度の成果を以下にまとめる. 1.衛星データを用いた大気エアロゾル特性の導出精度向上 衛星搭載偏光センサーデータ(ADEOS/POLDER)を用いて,対流圏エアロゾル粒子特性導出に際し,偏光情報の有効利用と地表面反射光の変更を考慮する事により,陸域エアロゾル特性の導出制度を向上させた 2.衛星データを用いた地表面反射偏光特性の考察 陸域エアロゾル特性導出精度向上のため、POLDERセンサデータ、IGBP土地被服分類データ)を用いて、地表面反射偏光特性を考察、導出した。 3.衛星データを用いた大気水蒸気量の導出 衛星データ(ADEOS/POLDER, OCTS)を用いた海陸上空大気水蒸気量の導出 4.大気エアロゾルの地上観測 和歌山県白浜(AERONET),東大阪(AERONET, SKYNET),長崎県福江島(新規SKYNET),石川県柳田村(AERONET臨時サイト)の4ヶ所にて放射計を設置・運用を行い,エアロゾルの連続観測を実施した.観測結果は,NASA/AERONET(白浜,能登,東大阪),SKYNET(福江,東大阪)としてWeb上でデータが公開が行われている.(AERONET ; http://aeronet.gsfc.nasa.gov, SKYNET) 5.大気エアロゾルと大気汚染物質の関係 環境省管轄の大気監視局データ(SPM他)の解析と表示システムの作成、並びに大気放射観測、衛星解析から得られたエアロゾル特性との相互参照から、明らかな相関関係のあることが判明した。 新たに測定機器を導入し、PM2.5の計測を開始した(H16年3月15日)。