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Aircraft-Measured Indirect Cloud Effects from Biomass Burning Smoke in the Arctic and SubarcticThe incidence of wildfires in the Arctic and subarctic is increasing; in boreal North America, for example, the burned area is expected to increase by 200-300% over the next 50-100 years, which previous studies suggest could have a large effect on cloud microphysics, lifetime, albedo, and precipitation. However, the interactions between smoke particles and clouds remain poorly quantified due to confounding meteorological influences and remote sensing limitations. Here, we use data from several aircraft campaigns in the Arctic and subarctic to explore cloud microphysics in liquid-phase clouds influenced by biomass burning. Median cloud droplet radii in smoky clouds were approx. 40- 60% smaller than in background clouds. Based on the relationship between cloud droplet number (N(liq)/ and various biomass burning tracers (BBt/ across the multi-campaign data set, we calculated the magnitude of subarctic and Arctic smoke aerosol-cloud interactions (ACIs, where ACI = (1/3) x dln(N(liq))/dln(BBt)) to be approx. 0.16 out of a maximum possible value of 0.33 that would be obtained if all aerosols were to nucleate cloud droplets. Interestingly, in a separate subarctic case study with low liquid water content (0.02 gm/cu m and very high aerosol concentrations (2000- 3000/ cu cm in the most polluted clouds, the estimated ACI value was only 0.05. In this case, competition for water vapor by the high concentration of cloud condensation nuclei (CCN) strongly limited the formation of droplets and reduced the cloud albedo effect, which highlights the importance of cloud feedbacks across scales. Using our calculated ACI values, we estimate that the smoke-driven cloud albedo effect may decrease local summertime short-wave radiative flux by between 2 and 4 W/sq m or more under some low and homogeneous cloud cover conditions in the subarctic, although the changes should be smaller in high surface albedo regions of the Arctic.We lastly explore evidence suggesting that numerous northern-latitude background Aitken particles can interact with combustion particles, perhaps impacting their properties as cloud condensation and ice nuclei.
Document ID
20160002954
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Zamora, L. M.
(Oak Ridge Associated Universities Greenbelt, MD, United States)
Kahn, R. A.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Cubison, M. J.
(Colorado Univ. Boulder, CO, United States)
Diskin, G. S.
(NASA Langley Research Center Hampton, VA, United States)
Jimenez, J. L.
(Colorado Univ. Boulder, CO, United States)
Kondo, Y.
(National Inst. of Polar Research Tokyo, Japan)
McFarquhar, G. M.
(Illinois Univ. at Urbana-Champaign Urbana, IL, United States)
Nenes, A.
(Georgia Inst. of Tech. Atlanta, GA, United States)
Thornhill, K. L.
(Science Systems and Applications, Inc. Hampton, VA, United States)
Wisthaler, A.
(Oslo Univ. Norway)
Zelenyuk, A.
(Pacific Northwest National Lab. Richland, WA, United States)
Ziemba, L. D.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
March 3, 2016
Publication Date
January 21, 2016
Publication Information
Publication: Atmospheric Chemistry and Physics
Publisher: European Geophysical Union
Volume: 16
Issue: 2
Subject Category
Meteorology And Climatology
Environment Pollution
Report/Patent Number
GSFC-E-DAA-TN29947
Funding Number(s)
CONTRACT_GRANT: NNL11AA00B
CONTRACT_GRANT: NNH06CC03B
Distribution Limits
Public
Copyright
Other
Keywords
cloud microphysics
biomass burning smoke
arctic

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