Vertical distribution of the Asian tropopause aerosols detected by CALIPSO

Hewen Niu; Shichang Kang; Wanni Gao; Yuhang Wang; Rukumesh Paudyal

doi:10.1016/j.envpol.2019.06.111

Vertical distribution of the Asian tropopause aerosols detected by CALIPSO

Environ Pollut. 2019 Oct:253:207-220. doi: 10.1016/j.envpol.2019.06.111. Epub 2019 Jul 10.

Authors

Hewen Niu¹, Shichang Kang², Wanni Gao³, Yuhang Wang⁴, Rukumesh Paudyal⁵

Affiliations

¹ State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
² State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences (UCAS), Beijing, 10049, China. Electronic address: shichang.kang@lzb.ac.cn.
³ School of International Cultural Exchange, Lanzhou University, Lanzhou, 730000, China.
⁴ School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
⁵ State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.

PMID: 31310871
DOI: 10.1016/j.envpol.2019.06.111

Abstract

Characterizing the vertical distribution of aerosol optical properties is crucial to reduce the uncertainty in quantifying the radiative forcing and climate effects of aerosols. The analysis of four-year (2007-2010) Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar measurements revealed the existence of tropospheric aerosol layers associated with the Asian summer monsoon. The measurements of five typical aerosol optical and microphysical parameters were used to explore the properties, spatial/vertical distributions, annual evolution of tropopause aerosols over the South Asia region. Results extracted from various latitude-height and longitude-height cross sections of aerosol extinction coefficient at 532 and 1064 nm, backscatter coefficient at 532 nm, and depolarization ratio at 532 nm demonstrated that a large amount of aerosols vertically extended up to the tropopause (12 km) during the monsoon season over the north Arabian Sea, India, north Bay of Bengal, and equatorial Indian Ocean, finally reaching the southeast of the Tibetan Plateau. Convective transport associated with Asian summer monsoon is an important factor controlling the vertical distribution of tropopause aerosols. The evolution of aerosol scattering ratio at 532 nm indicated that from equatorial Indian Ocean to South Asia, there exists an upward tilting and ascending structure of the aerosols layer during the monsoon season, which typically indicates enhanced aerosols over the Asian monsoon region. Information on aerosol size distribution and detailed composition are needed for better understanding the nature and origin of this aerosol layer. Enhancement of the tropopause aerosols should be considered in the future studies in evaluating the regional or global climate systems. Further satellite observations of aerosols and in-situ observations are also urgently needed to diagnose this aerosol layer, which likely originate from anthropogenic emissions.

Keywords: Aerosol; Asian summer monsoon; Tropopause; Vertical.

MeSH terms

Aerosols / analysis*
Air Pollutants / analysis*
Asia
Atmosphere / chemistry
Climate
Environmental Monitoring / methods*
India
Indian Ocean
Seasons

Substances

Aerosols
Air Pollutants