Source attribution of Arctic black carbon constrained by aircraft and surface measurements


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Andreas.Herber [ at ] awi.de

Abstract

Black carbon (BC) contributes to Arctic warm- ing, yet sources of Arctic BC and their geographic con- tributions remain uncertain. We interpret a series of recent airborne (NETCARE 2015; PAMARCMiP 2009 and 2011 campaigns) and ground-based measurements (at Alert, Bar- row and Ny-Ålesund) from multiple methods (thermal, laser incandescence and light absorption) with the GEOS-Chem global chemical transport model and its adjoint to attribute the sources of Arctic BC. This is the first comparison with a chemical transport model of refractory BC (rBC) measure- ments at Alert. The springtime airborne measurements per- formed by the NETCARE campaign in 2015 and the PA- MARCMiP campaigns in 2009 and 2011 offer BC vertical profiles extending to above 6 km across the Arctic and in- clude profiles above Arctic ground monitoring stations. Our simulations with the addition of seasonally varying domes- tic heating and of gas flaring emissions are consistent with ground-based measurements of BC concentrations at Alert and Barrow in winter and spring (rRMSE < 13 %) and with airborne measurements of the BC vertical profile across the Arctic (rRMSE = 17 %) except for an underestimation in the middle troposphere (500–700 hPa). Sensitivity simulations suggest that anthropogenic emis- sions in eastern and southern Asia have the largest effect on the Arctic BC column burden both in spring (56 %) and annu ally (37 %), with the largest contribution in the middle tropo- sphere (400–700 hPa). Anthropogenic emissions from north- ern Asia contribute considerable BC (27% in spring and 43 % annually) to the lower troposphere (below 900 hPa). Biomass burning contributes 20 % to the Arctic BC column annually. At the Arctic surface, anthropogenic emissions from northern Asia (40–45 %) and eastern and southern Asia (20– 40 %) are the largest BC contributors in winter and spring, followed by Europe (16–36 %). Biomass burning from North America is the most important contributor to all stations in summer, especially at Barrow. Our adjoint simulations indicate pronounced spatial het- erogeneity in the contribution of emissions to the Arctic BC column concentrations, with noteworthy contributions from emissions in eastern China (15 %) and western Siberia (6.5 %). Although uncertain, gas flaring emissions from oil- fields in western Siberia could have a striking impact (13 %) on Arctic BC loadings in January, comparable to the total influence of continental Europe and North America (6.5 % each in January). Emissions from as far as the Indo-Gangetic Plain could have a substantial influence (6.3 % annually) on Arctic BC as well.



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Published
Eprint ID
46146
DOI 10.5194/acp-17-11971-2017

Cite as
Xu, J. W. , Martin, R. W. , Morrow, A. , Sharma, S. , Huang, L. , Leaitch, W. R. , Burkart, J. , Schulz, H. , Zanatta, M. , Willis, M. D. , Henze, D. K. , Lee, C. J. , Herber, A. B. and Abbatt, J. P. D. (2017): Source attribution of Arctic black carbon constrained by aircraft and surface measurements , Atmospheric Chemistry and Physics, 17 , pp. 11971-11989 . doi: 10.5194/acp-17-11971-2017


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