Distribution of (a) DOC (mg L−1), (b) TN (mg L−1), (c) BC (μg L−1), and (d) major ions (μg L−1) in Alaskan snow cover in the spring of 2017. (Detailed sampling information can be referred to supplementary Table S1.).
Table 1.
DOC concentrations measured in snow of Alaska and Barrow and comparison with previous studies.
RegionSampling periodSnow typesDOC conc. (mg L−1)Sample sizeReferencesBarrowApr to May 2017Surface snow0.17 ± 0.0535This studyAcross Alaskan regionsApr 2017Surface snow0.30 ± 0.1827This studyJuneau Icefield, Southeast AlaskaMay 2013Glacial surface snow0.2010Fellman et al. (2015)Mendenhall Glacier, AlaskaSnowpit0.191Stubbins et al. (2012)Mt. Blanc, French AlpsSept. 2012Surface snow0.11 ± 0.014Legrand et al. (2013)Mt. Blanc, French AlpsSept. 2012Snowpit0.304Legrand et al. (2013)Glacier No.1, TienshanAug. 2014Snowpit0.52 ± 0.146–16Liu et al. (2016)Glacier No.1, TienshanMay 26 to Oct 4, 2013Surface snow0.35 ± 0.0978Li et al. (2018)LHG glacier No.12, northern Tibetan PlateauJul to Aug 2015Surface snow0.34 ± 0.14184Yan et al. (2016)LHG glacier No.12, northern, Northern Tibetan PlateauAug. 2014Snowpit0.66 ± 0.086–16Liu et al. (2016)XDKMD glacier, central Tibetan PlateauMay 29 to Sep30, 2013Surface snow1.17 ± 0.34374Li et al. (2018)XDKMD glacier, Central Tibetan PlateauAug 2014Snowpit0.64 ± 0.506–16Liu et al. (2016)Mountain glaciersMeanSurface snow0.49 ± 0.0735Hood et al. (2015)Greenland Ice SheetMeanSurface snow0.20 ± 0.014Hood et al. (2015)Greenland Ice SheetMay to Aug 2012Snow0.061Musilova et al. (2017)Greenland Ice SheetMay to Aug 2012Ice0.18Musilova et al. (2017)Dry Valleys, Antarctic Ice SheetMeanSurface snow0.46 ± 0.127Hood et al. (2015)Vostok, Antarctic Ice SheetIce, 8300 BPIce core0.0058 ± 0.00143Legrand et al. (2013)Dome CIce, 10300 BPIce core0.021 ± 0.0054Legrand et al. (2013)
Fig. 2.
Vertical variations of DOC concentrations and other parameters recorded in the snowpack at Barrow, Alaska.
Fig. 3.
Comparison of DOC (mg L−1), TN (mg L−1), BC (μg L−1), and major ions (μg L−1) in surface and subsurface snow cover at Barrow.
Table 2.
Absorption Ångström Exponent (AAE330 − 400) and mass absorption cross section of DOC in snow across Alaska and at Barrow, as well as a comparison with other studies on snow and aerosols from other regions.
Study area/sourceAverage AAE330-400Average MACDOC365 (m2 g-1)λ (MAC, nm)ReferenceSurface snow, Barrow2.11 ± 1.180.32 ± 0.24365This studySurface snow, across Alaska2.34 ± 0.780.37 ± 0.32365This studyHULIS, Arctic snow6.1a2.6 ± 1.1250Voisin et al. (2012)Non-BC light absorbing constituents, Arctic snow2.3 ± 0.3Doherty et al. (2010)LHG glacier, Tibetan Plateau5.0 ± 5.91.4 ± 0.4365Yan et al. (2016)DOC in precipitation, Tibetan Plateau0.25 − 0.64365Li et al. (2017)Water-soluble organic carbon aerosols, South Tibetan Plateau0.84 − 1.18365Li et al. (2017)Water-soluble organic carbon aerosols, northern China6.4 ± 0.60.7 ± 0.2365Kirillova et al. (2014)Secondary organic carbon5.2 − 8.80.001 − 0.088405Lambe et al. (2013)Water-soluble OC, Wood smoke8.6 − 17.80.13 − 1.1400Chen and Bond (2010)Humic-like organic carbon aerosol41.2300 − 650Sun et al. (2007)Biomass smoke4.85.0350Kirchstetter et al. (2004)BrC aerosol, Beijing, China (winter)7.1b1.45365Cheng et al. (2016)BrC aerosol, North American continental troposphere6.82 ± 2.63cLiu et al. (2015)Water-soluble OC, Indian Ocean0.5 ± 0.2365Bosch et al. (2014)BrC aerosol, India5.1 ± 1.91.3 ± 0.7365Srinivas et al. (2016)
a Wavelength range for AAE in this study is 300 − 550 nm.
b Wavelength range for AAE in this study is 310 − 450 nm.
c Wavelength range for AAE in this study is 300 − 450 nm.
Fig. 4.
Relationship between (a) MACDOC365 values and DOC concentrations, (b) MACDOC365 values and AAE330-400, and (c) SUVA254 and DOC concentrations for Alaskan snow samples, and temporal variation in MACDOC365 values (d), and SUVA254 Values (e) in snow cover on the sea ice at Barrow during the study period of April to May in 2017.
Fig. 5.
Variation for ratios (a) of RF by DOC to BC, and relationships between ratios of RF by DOC to BC and (b) MACDOC365 and (c) ratios of DOC/BC in the snow at Barrow, Alaska.
Fig. 6.
Exponential decrease of DOC concentrations in snow cover on Chukchi sea ice during the biodegradation experiment in May of 2017 at Barrow.
Fig. 7.
Footprint analyses of the backward trajectories launched over the snow sampling site at Barrow, Alaska, during April and May in 2017 for pass by (a) 48 h and (b) 120 h, respectively, and HYSPLIT model seven day back trajectories for air masses arriving in Barrow on (c) April 17, 2017 and (d) May 2, 2017. (Different colors of backward trajectories in c and d represent the air mass arrived at the different date.).
Table 3.
Principal component analysis of DOC with other parameters in snow over across the Alaska and on sea ice at Barrow.
Barrow snowSnow across AlaskaPCA1 (%)PCA2 (%)PCA3 (%)PCA1 (%)PCA2 (%)PCA3 (%)DOC0.871.7980.691.0933.615.71TN11.0616.1555.1351.110.6130.06BC3.2441.182.271.860.0767.81Cl-88.733.421.787.9640.3212.92SO42-13.2963.590.3986.274.440.97NO3-0.0550.3820.5769.870.0111.99Na+87.824.780.903.2161.3110.92NH4+14.3162.230.2734.000.2450.68K+84.468.530.691.7865.411.28Mg2+63.669.342.4081.210.000.26Ca2+10.973.0226.9651.942.101.59Variance of extraction34.41%24.04%17.46%35.48%18.92%17.65%Accumulated variance75.90%72.05%
Fig. 8.
Biplot analyses of DOC with other parameters for (a) snow samples in Barrow, and (b) snow samples across Alaska.
