Sonoyo Mukai

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.

Air pollutants in Osaka (Japan)

Increasing emission of anthropogenic particles is causing heavy air pollution. This work intends to analyze the air pollution in greater metropolitan area of Asia and its influence on the environment. We focus on Osaka in Japan because our group has been monitoring suspended particulate matter (PM) at Osaka/AERONET since 2004. PM is usually used as an indicator of air quality, because high PM concentrations can degrade air quality. Osaka is the second largest metropolitan region of Japan and its air is significantly polluted by anthropogenic particles emitted from vehicles and industry. In this study, seasonal variation of air pollutants in Osaka is investigated using ground observations such as PM sampling, AERONET photometry, and numerical model simulation. Results indicate that PM concentrations are high during spring and summer because of yellow dust events and photochemical reactions, respectively. In addition, the impact of anthropogenic PM around Osaka is significant in summer.

Role of near ultraviolet wavelength measurements in the detection and retrieval of absorbing aerosols from space

Aerosol remote sensing by ultraviolet (UV) wavelength is established by a Total Ozone Mapping Spectrometer (TOMS) mounted on the long-life satellite Nimbus-7 and continues to make observations using Ozone monitoring instrument (OMI) located on the Aura satellite. For example, TOMS demonstrated that UV radiation (0.331 and 0.360 μm) could easily detect absorbing particles such as mineral dust or smoke aerosols. TOMS-AI (absorbing aerosol index) has been used to identify the absorbing aerosols from space. For an upcoming mission, JAXA/GCOM-C will have the polarization sensor SGLI boarded in December 2017. The SGLI has multi (19)-channels including near UV (0.380 μm) and violet (0.412 μm) wavelengths. This work intends to examine the role of near UV data in the detection of absorbing aerosols similar to TOMS-AI played. In practice, the measurements by GLI mounted on the short Japanese mission JAXA/ADEOS-2, whose data archive period was just 8 months from April to October in 2003, are available for simulation of SGLI data because ADEOS-2/GLI installed near UV and violet channels. First of all, the ratio of data at 0.412 μm to that at 0.380 μm is examined as an indicator to detect absorbing aerosols on a global scale during ADEOS-2 era. It is noted that our research group has developed an efficient algorithm for aerosol retrieval in hazy episodes (dense concentrations of atmospheric aerosols). It can be said that at least this work is an attempt to grasp the biomass burning plumes from the satellite.

Improvement of retrieval algorithms for severe air pollution

Increased emissions of anthropogenic aerosols associated with economic growth can lead to increased concentrations of hazardous air pollutants. Furthermore, dust storms or biomass burning plumes can cause serious environmental hazards, yet their aerosol properties are poorly understood. Our research group has worked on the development of an efficient algorithm for aerosol retrieval during hazy episodes (dense concentrations of atmospheric aerosols). It is noted that near UV measurements are available for detection of carbonaceous aerosols. The biomass burning aerosols (BBA) due to large-scale forest fires and/or burn agriculture exacerbated the severe air pollution. It is known that global warming and climate change have caused increasing instances of forest fires, which have in turn accelerated climate change. It is well known that this negative cycle decreases the quality of the global environment and human health. The Japan Aerospace Exploration Agency (JAXA) has been developing a new Earth observing system, the GCOM (Global Change Observation Mission) project, which consists of two satellite series: GCOM-W1 and GCOM-C1. The first GCOM-C satellite will board the SGLI (second generation GLI [global imager]) to be launched in early 2017. The SGLI is capable of multi-channel (19) observation, including a near UV channel (0.380 μm) and two polarization channels at red and near-infrared wavelengths of 0.67 and 0.87 μm. Thus, global aerosol retrieval will be achieved with simultaneous polarization and total radiance. In this study, algorithm improvement for aerosol remote sensing, especially of BBA episodes, is examined using Terra/MODIS measurements from 2003, when the GLI and POLDER-2 sensors were working onboard the Japanese satellite ADEOS-2.

Retrieval for PM 2.5 distribution from space

Concentration of particulate matter (PM2.5) is a good indicator of air pollution by anthropogenic aerosols in particular near surface. However instrumentation of PM2.5 is still on going in East Asia even in Japan. This work intends to develop an algorithm for estimating PM2.5 distribution based on the satellite measurements. Combined use of satellite derived columnar aerosol optical thickness (AOT) and vertical distribution of aerosol extinction by ground-based LIDAR measurements is available for estimation of near surface AOT. Thus the derived correlation between AOT and PM2.5 is utilized to retrieve satellite based PM2.5.

Discrimination and retrieval of aerosol types using multi-channels including near-UV and polarization by GCOM-C/SGLI

The second global imager (SGLI) is on board the Japanese mission GCOM-C (SHIKISAI in Japanese), which was launched on December 23, 2017. The SGLI has multiple channels (19), including near-UV (0.380 μm) and violet (0.412 μm) wavelengths, and polarization channels in the red and near-IR wavelengths. This study aimed to demonstrate such advantages of SGLI as near-UV and polarization measurements for aerosol remote sensing. The role of near UV data in the detection of absorbing aerosols, such as biomass burning aerosols (BBA) or mineral dust, is examined on a global scale. Not only is this absorbing aerosol index defined in the near-UV wavelength region, but short wavelength infrared measurements were utilized to discriminate BBA from mineral dust particles. First, an understanding of aerosol types facilitates subsequent aerosol retrieval. Then, the characterization for classified aerosols is made based on the radiation simulations with multi-spectral radiance and polarization measurements in the red and near- IR.

Remote Sensing of Heavy Aerosol Pollution Episodes: Smoke and Dust

Abstract In this chapter, we observe the remote sensing of aerosols in heavy pollution episodes. Extreme concentrations of aerosols in the atmosphere, such as dust storms or biomass burning plumes, prevent aerosol monitoring from the ground surface, whereas satellite observation can still be available from space. This chapter has two major parts. In the first part, we focus on the interpretation of the approaches for detecting heavy aerosol episodes such as dust storms and biomass burning plumes; the second part describes the algorithms for aerosol retrieval and showcases an example of the retrieved aerosol properties in the heavy biomass burning episodes in Siberia. In addition, polarization remote sensing is briefly mentioned as a promising tool for this field.

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.

Response of the climate system to anthropogenic aerosols

In general, aerosols influence the climate directly by scattering and absorbing the solar radiation and indirectly by acting as cloud condensation nuclei and ice nuclei, which modify the radiative properties of clouds. To estimate the effects of anthropogenic aerosols on the climate in future, we used earth system model simulations. The emission of anthropogenic aerosols can be decreased by controlling air pollution. If the emission of anthropogenic aerosol drops to zero abruptly, the surface temperature will rise in a short span of time. However, the surface temperature will decrease if the emission of anthropogenic aerosols is doubled suddenly. These results indicate that aerosols have immediate effects on climate change.