Black Carbon and Inorganic Aerosols in Arctic Snowpack

• Published in: Journal of geophysical research. Atmospheres 2019-12, Vol.124 (23), p.13325-13356
• Main Authors: Mori, Tatsuhiro, Goto‐Azuma, Kumiko, Kondo, Yutaka, Ogawa‐Tsukagawa, Yoshimi, Miura, Kazuhiko, Hirabayashi, Motohiro, Oshima, Naga, Koike, Makoto, Kupiainen, Kaarle, Moteki, Nobuhiro, Ohata, Sho, Sinha, P.R., Sugiura, Konosuke, Aoki, Teruo, Schneebeli, Martin, Steffen, Konrad, Sato, Atsushi, Tsushima, Akane, Makarov, Vladimir, Omiya, Satoshi, Sugimoto, Atsuko, Takano, Shinya, Nagatsuka, Naoko
• Format: Article
• Language: English
• Subjects: Aerosols; Albedo; Albedo (solar); Anthropogenic factors; Arctic; Arctic aerosols; Arctic climates; Arctic snow; Arctic zone; Atmospheric models; Atmospheric particulates; Biomass burning; Black carbon; Carbon; Carbon aerosols; Chromatography; Climate; Climate models; deposition; Dust storms; Emission analysis; Fossil fuels; Geophysics; Human influences; Ice environments; inorganic aerosols; Laser induced incandescence; Lasers; Latitudinal variations; Mathematical models; New records; Numerical models; Photometers; Precipitable water; Radiative forcing; Regions; single‐particle soot photometer; Snow; Snow accumulation; Snow-water equivalent; Snowmelt; Snowpack; Solar radiation; Soot; Spatial distribution; Species; Spectrophotometers; Spring; Spring (season); Topography (geology)
• ISSN: 2169-897X; 2169-8996
• DOI: 10.1029/2019JD030623

Black carbon (BC) deposited on snow lowers its albedo, potentially contributing to warming in the Arctic. Atmospheric distributions of BC and inorganic aerosols, which contribute directly and indirectly to radiative forcing, are also greatly influenced by depositions. To quantify these effects, accurate measurement of the spatial distributions of BC and ionic species representative of inorganic aerosols (ionic species hereafter) in snowpack in various regions of the Arctic is needed, but few such measurements are available. We measured mass concentrations of size‐resolved BC (CMBC) and ionic species in snowpack by using a single‐particle soot photometer and ion chromatography, respectively, over Finland, Alaska, Siberia, Greenland, and Spitsbergen during early spring in 2012–2016. Total BC mass deposited per unit area (DEPMBC) during snow accumulation periods was derived from CMBC and snow water equivalent (SWE). Our analyses showed that the spatial distributions of anthropogenic BC emission flux, total precipitable water, and topography strongly influenced latitudinal variations of CMBC, BC size distributions, SWE, and DEPMBC. The average size distributions of BC in Arctic snowpack shifted to smaller sizes with decreasing CMBC due to an increase in the removal efficiency of larger BC particles during transport from major sources. Our measurements of CMBC were lower by a factor of ~13 than previous measurements made with an Integrating Sphere/Integrating Sandwich spectrophotometer due mainly to interference from coexisting non‐BC particles such as mineral dust. The SP2 data presented here will be useful for constraining climate models that estimate the effects of BC on the Arctic climate. Plain Language Summary Black carbon (BC) particles, commonly known as soot, are emitted from incomplete combustion of fossil fuels and biomass. They efficiently absorb solar radiation and thus heat the atmosphere. BC particles emitted at midlatitudes and in the Arctic are deposited onto snow in the Arctic, accelerating snowmelt in early spring by absorbing solar radiation. These processes contribute to warming in the Arctic. Calculations of this warming effect by using numerical models need to be validated by comparison with observed BC concentrations in snowpack. However, there are very few accurate records of concentrations of BC in snow because of technical difficulties in making these measurements. We developed a new laser‐induced incandescence technique to measure BC