Interannual variability and trends of combustion aerosol and dust in major continental outflows revealed by MODIS retrievals and CAM5 simulations during 2003–2017

Journal Article · 03 January 2020 · Atmospheric Chemistry and Physics (Online)

DOI: https://doi.org/10.5194/acp-20-139-2020 · OSTI ID:1592420

Yu, Hongbin ^[1]; Yang, Yang  ^[2]; Wang, Hailong ^[2]; Tan, Qian ^[3]; Chin, Mian ^[1]; Levy, Robert C.  ^[1]; Remer, Lorraine A. ^[4]; Smith, Steven J.  ^[2]; Yuan, Tianle ^[5]; Shi, Yingxi ^[5]

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1. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
3. Bay Area Environmental Research Institute, Petaluma, CA (United States); NASA Ames Research Center, Moffett Field, CA (United States)
4. Univ. of Maryland Baltimore County (UMBC), Baltimore, MD (United States)
5. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Maryland Baltimore County (UMBC), Baltimore, MD (United States)

Emissions and long-range transport of mineral dust and combustion-related aerosol from burning fossil fuels and biomass vary from year to year, driven by the evolution of the economy and changes in meteorological conditions and environmental regulations. This study offers both satellite and model perspectives on the interannual variability and possible trends of combustion aerosol and dust in major continental outflow regions over the past 15 years (2003–2017). The decade-long record of aerosol optical depth (AOD, denoted as τ), separately for combustion aerosol (τ_c) and dust (τ_d), over global oceans is derived from the Collection 6 aerosol products of the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard both Terra and Aqua. These MODIS Aqua datasets, complemented by aerosol source-tagged simulations using the Community Atmospheric Model version 5 (CAM5), are then analyzed to understand the interannual variability and potential trends of τ_c and τ_d in the major continental outflows. Both MODIS and CAM5consistently yield a similar decreasing trend of –0.017 to –0.020 per decade for τ_c over the North Atlantic Ocean and the Mediterranean Sea that is attributable to reduced emissions from North America and Europe, respectively. On the contrary, both MODIS and CAM5 display an increasing trend of +0.017 to +0.036 per decade for τ_c over the tropical Indian Ocean, the Bay of Bengal, and the Arabian Sea, which reflects the influence of increased anthropogenic emissions from South Asia and the Middle East in the last 2 decades. Over the northwestern Pacific Ocean, which is often affected by East Asian emissions of pollution and dust, the MODIS retrievals show a decreasing trend of –0.021 per decade for τ_c and –0.012 per decade for τ_d, which is, however, not reproduced by the CAM5 model. In other outflow regions strongly influenced by biomass burning smoke or dust, both MODIS retrievals and CAM5 simulations show no statistically significant trends; the MODIS-observed interannual variability is usually larger than that of the CAM5 simulation.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: AC05-76RL01830
• OSTI ID: 1592420
• Report Number(s): PNNL-SA-147334; TRN: US2100904
• Journal Information: Atmospheric Chemistry and Physics (Online), Vol. 20, Issue 1; ISSN 1680-7324
• Publisher: European Geosciences UnionCopyright Statement
• Country of Publication: United States
• Language: English