Vertical profiles of light absorption and scattering associated with black carbon particle fractions in the springtime Arctic above 79° N
[2];
[3];
[5];
[6];
[7];
[7];
[10];
[11];
[9];
[12];
[13];
[14]
- Environment and Climate Change Canada, Toronto, ON (Canada)
- Colorado State Univ., Fort Collins, CO (United States); Foundation for Research and Technology (FORTH), Padras (Greece). Inst. of Chemical Engineering Sciences (ICE)
- Univ. of Toronto, ON (Canada); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Univ. of British Columbia, Vancouver, BC (Canada); Environment and Climate Change Canada, Victoria, BC (Canada)
- Helmoltz Center for Polar and Marine Research, Bremerhaven (Germany)
- Univ. of Colorado, Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences (CIRES); National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States)
- Johannes Gutenberg Univ., Mainz (Germany)
- Univ. of Toronto, ON (Canada); Univ. of Vienna (Austria)
- Environment and Climate Change Canada, Victoria, BC (Canada)
- National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States)
- Univ. of British Columbia, Vancouver, BC (Canada); Univ. of Toronto Scarborough, Toronto, ON (Canada)
- Univ. of British Columbia, Vancouver, BC (Canada)
- Univ. of Toronto, ON (Canada)
- Colorado State Univ., Fort Collins, CO (United States)
Despite the potential importance of black carbon (BC) for radiative forcing of the Arctic atmosphere, vertically resolved measurements of the particle light scattering coefficient (σsp) and light absorption coefficient (σap) in the springtime Arctic atmosphere are infrequent, especially measurements at latitudes at or above 80° N. Here, relationships among vertically distributed aerosol optical properties (σap, σsp and single scattering albedo or SSA), particle microphysics and particle chemistry are examined for a region of the Canadian archipelago between 79.9 and 83.4° N from near the surface to 50 hPa. Airborne data collected during April 2015 are combined with ground-based observations from the observatory at Alert, Nunavut and simulations from the Goddard Earth Observing System (GEOS) model, GEOS-Chem, coupled with the TwO-Moment Aerosol Sectional (TOMAS) model (collectively GEOS-Chem–TOMAS; Kodros et al., 2018) to further our knowledge of the effects of BC on light absorption in the Arctic troposphere. The results are constrained for σsp less than 15 Mm-1, which represent 98% of the observed σsp, because the single scattering albedo (SSA) has a tendency to be lower at lower σsp, resulting in a larger relative contribution to Arctic warming. At 18.4 m2g-1, the average BC mass absorption coefficient (MAC) from the combined airborne and Alert observations is substantially higher than the two averaged modelled MAC values (13.6 and 9.1 m2 g-1) for two different internal mixing assumptions, the latter of which is based on previous observations. The higher observed MAC value may be explained by an underestimation of BC, the presence of small amounts of dust and/or possible differences in BC microphysics and morphologies between the observations and model. In comparing the observations and simulations, we present σap and SSA, as measured, and σap 2 and the corresponding SSA to encompass the lower modelled MAC that is more consistent with accepted MAC values. Median values of the measured σap, rBC and the organic component of particles all increase by a factor of 1.8±0.1, going from near-surface to 750 hPa, and values higher than the surface persist to 600 hPa. Modelled BC, organics and σap agree with the near-surface measurements but do not reproduce the higher values observed between 900 and 600 hPa. The differences between modelled and observed optical properties follow the same trend as the differences between the modelled and observed concentrations of the carbonaceous components (black and organic). Model-observation discrepancies may be mostly due to the modelled ejection of biomass burning particles only into the boundary layer at the sources. For the assumption of the observed MAC value, the SSA range between 0.88 and 0.94, which is significantly lower than other recent estimates for the Arctic, in part reflecting the constraint of σsp<15 Mm-1. The large uncertainties in measuring optical properties and BC, and the large differences between measured and modelled values here and in the literature, argue for improved measurements of BC and light absorption by BC and more vertical profiles of aerosol chemistry, microphysics and other optical properties in the Arctic.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Atmospheric Radiation Measurement (ARM) Data Center
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Contributing Organization:
- PNNL, BNL, ANL, ORNL
- Grant/Contract Number:
- SC0011780
- OSTI ID:
- 1671742
- Journal Information:
- Atmospheric Chemistry and Physics (Online), Vol. 20, Issue 17; ISSN 1680-7324
- Publisher:
- European Geosciences UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
AeroCom phase III multi-model evaluation of the aerosol life cycle and optical properties using ground- and space-based remote sensing as well as surface in situ observations
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journal | January 2021 |
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