Title Aircraft observations of enhancement and depletion of black carbon mass in the springtime Arctic
Author Spackman, J.R.; Gao, R.S.; Neff, W.D.; Schwarz, J.P.; Watts, L.A.; Fahey, D.W.; Holloway, J.S.; Ryerson, T.B.; Peischl, J.; Brock, C.A.
Author Affil Spackman, J.R., NOAA, Earth System Research Laboratory, Boulder, CO. Other: University of Colorado
Source Atmospheric Chemistry and Physics, 10(19), p.9667-9680, . Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1680- 7316
Publication Date 2010
Notes In English. Part of special issue no. 182, POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport), edited by Stohl, A., et al., http://www.atmos-chem- phys.net/special_issue182.html; published in Atmospheric Chemistry and Physics Discussions: 21 June 2010, http://www.atmos- chem-phys-discuss.net/10/15167/2010/acpd-10- 15167-2010. html; accessed in May, 2011. 50 refs. GeoRef Acc. No: 310395
Index Terms adsorption; aircraft; atmospheric boundary layer; biomass; boundary layer; climate; climatic change; fires; human activity; ice; meteorology; ozone; pollution; remote sensing; snow; statistical analysis; Arctic region; United States--Alaska-- Fairbanks; Alaska; annual variations; atmosphere; black carbon; bromine; carbon monoxide; climate change; depletion; deposition; Fairbanks Alaska; halogens; observations; sea ice; time series analysis; troposphere; United States
Abstract Understanding the processes controlling black carbon (BC) in the Arctic is crucial for evaluating the impact of anthropogenic and natural sources of BC on Arctic climate. Vertical profiles of BC mass loadings were observed from the surface to near 7-km altitude in April 2008 using a Single-Particle Soot Photometer (SP2) during flights on the NOAA WP-3D research aircraft from Fairbanks, Alaska. These measurements were conducted during the NOAA-sponsored Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) project. In the free troposphere, the Arctic air mass was influenced by long-range transport from biomass-burning and anthropogenic source regions at lower latitudes especially during the latter part of the campaign. Average BC mass mixing ratios peaked at about 150 ng BC (kg dry air )-1 near 5.5 km altitude in the aged Arctic air mass and 250 ng kg-1 at 4.5 km in biomass-burning influenced air. BC mass loadings were enhanced by up to a factor of 5 in biomass-burning influenced air compared to the aged Arctic air mass. At the bottom of some of the profiles, positive vertical gradients in BC were observed over the sea- ice. The vertical profiles generally occurred in the vicinity of open leads in the sea-ice. In the aged Arctic air mass, BC mass loadings more than doubled with increasing altitude within the ABL and across the boundary layer transition while carbon monoxide (CO) remained constant. This is evidence for depletion of BC mass in the ABL. BC mass loadings were positively correlated with O3 in ozone depletion events (ODEs) for all the observations in the ABL. Since bromine catalytically destroys ozone in the ABL after being released as molecular bromine in regions of new sea-ice formation at the surface, the BC-O3 correlation suggests that BC particles were removed by a surface process such as dry deposition. We develop a box model to estimate the dry deposition flux of BC mass to the snow constrained by the vertical profiles of BC mass in the ABL. Open leads in the sea-ice may increase vertical mixing and entrainment of pollution from the free troposphere possibly enhancing the deposition of BC aerosol to the snow.
URL http://www.atmos-chem-phys.net/10/9667/2010/acp-10-9667-2010.pdf
Publication Type journal article
Record ID 65007199