[H-CG26] 農業残渣焼却のもたらす大気汚染と健康影響および解決への道筋

[HCG26-03] Influences of Post-Monsoon Crop Residue Burning Activities on Aerosol, Cloud, and Radiation Fields over Northwestern India

*Khatri Pradeep¹、Hayasaka Tadahiro¹、Patra Prabir²、Letu Husi³、Jevtha Hiren^4,5、Hayashida Sachiko² (1.Center for Atmospheric and Oceanic Studies,Tohoku University、2.Research Institute for Humanity and Nature, Kyoto, Japan、3.Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing, China、4.Morgan State University, GESTAR-II, Baltimore, MD, USA、5.National Aeronautics and Space Administration, Goddard Space Flight Center, Greenbelt, USA)

キーワード：crop residue burning、aerosol 、cloud、radiation

The post-monsoon crop residue burning (CRB) activities in northwestern (NW) India are recognized as one of the major socio-environmental problems in recent years due to their severe impacts on air quality degradation over a wide area, including the capital New Delhi. Thus, these CRB activities have been extensively studied from an air quality perspective. On the other hand, despite their high potential impacts on the climate system via their influences on cloud and radiation fields, such studies have been merely overlooked until now. Here, we analyze fire, meteorological parameters, aerosol, cloud, and radiation data spanning nearly two decades (2002-2021), obtained from satellite observations and reanalysis to fill this research gap. With distinct inter-annual variations, such as an increasing trend of CRB intensity and CRB peak time, but a decreasing trend of the intense CRB period, these CRB activities are found to significantly increase the loadings of light-absorbing aerosols. The enhanced light-absorbing aerosols due to CRB activities are found to have profound impacts on both water cloud properties and the radiation field: cloud droplet size increases (cloud optical thickness decreases), likely due to the enhancement of the cloud droplet collision-coalescence process. Additionally, the surface and top-of-the-atmosphere are cooled due to atmospheric heating caused by aerosol absorption across the entire shortwave and longwave spectrum, although the effects at shortwave and longwave spectrums are in opposite direction. The atmospheric heating caused by aerosol absorption has implications in further deteriorating the air quality at ground by stabilizing the atmosphere and cooling the surface, thereby, inhibiting vertical mixing. These results emphasize the need for future studies to focus on the climatic influences of CRB activities to better understand their roles in the regional climate system and hydrological cycle.