Masayoshi Yasumoto

Estimation of Biomass Burning Influence on Air Pollution around Beijing from an Aerosol Retrieval Model

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.

Evaluation of air quality from space

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.

Combined use of OCTS and POLDER for cloud retrieval

Abstract OCTS and POLDER sensors were launched on ADEOS satellite in August 1996. It is well known that combination of multi-sensor data is useful to retrieve the physical properties of the Earth atmosphere from space. In this work, a procedure for cloud detection and distinction of thermodynamic phase of the top cloud is proposed based on the combined use of ADEOS/POLDER and OCTS. In practice, thermodynamic phase is distinguished by using polarized reflectance at 0.865 μm given by POLDER and brightness temperature at 10.9μm by OCTS. Further effective radius of water cloud particles is extracted from comparison of light scattering simulations with the polarization measurements by POLDER. In this work POLDER and OCTS data of Nov. 10, 1996 are examined.

Retrieval of aerosol episode due to agriculture biomass burning in the east-central China

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.

Interrelation of aerosols, water vapor and clouds on a global scale

Abstract 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 μm. The polarization data at 0.865 μm. 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 μm. and the second is in the gas absorption-free band of 0.865 pin. 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).

Calibration of the multispectral polarimeter and its measurements of atmospheric aerosols

PSR-1000 is a portable multispectral polarimeter which measures direct solar radiation and sky radiation at the same wavelength bands as a ADEOS/POLDER sensor. A calibration of our PSR-1000 was done based on Langley plot method involving gaseous absorption from October 27 to November 2 in 1997 at Mt. Mauna Kea in Hawaii Island. Then observations with the PSR-1000 were undertaken over the Seto Inland Sea of Japan in 1997, 1998 and 1999. This work describes a procedure to determine the calibration constants of PSR-1000 and an algorithm to retrieve aerosol characteristics from the polarization measurements of sky light.

Seasonal and Regional Characteristics of Aerosol Pollution in East and Southeast Asia

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.

Regional and seasonal effects on biomass burning aerosols

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.

Detection of severe air pollution from multidirectional perspectives

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 μm and 0.869 μm 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 remote sensing for Hazy atmosphere

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.