Black carbon and other light‐absorbing particles in snow of central North America

Doherty, Sarah J.; Dang, Cheng; Hegg, D́ean A.; Zhang, Rudong; Warren, Stephen G.

doi:10.1002/2014jd022350

Cited by 100 publications

(195 citation statements)

References 54 publications

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“…Doherty et al (2016) also calibrated the ISSW measurements using an incandescence technique (a singleparticle soot photometer, SP2) in a subset of the observations, which was intended to capture C BC more accurately, and derived a ratio of C BC by ISSW to C BC by SP2 based on their linear relationship for the estimation of real C BC . This calibration is applied to the dataset of Doherty et al (2014) in our study, and thus the observations of Doherty et al (2014Doherty et al ( , 2016 used here are comparable. In addition, Skiles and Painter (2016b) made daily measurements of BC-in-snow with an SP2 in the Senator Beck Basin Study Area (SBBSA) in the San Juan Mountains during a period of 2 months (late March to middle May) in 2013.…”

Section: Observationsmentioning

confidence: 99%

“…Although field observations of C BC in snow extend back to the 1980s, they were made mostly in the polar regions, the Alps, the Cascade Mountains, eastern Canada, and western Texas and New Mexico (see Qian et al, 2015 and references therein). Recently, Doherty et al (2014) made valuable measurements of the vertical profiles of LAAs in seasonal snow from January to March 2013 in the western US. They used an integrating sphere-integrating sandwich (ISSW) spectrophotometer to estimate the C BC over 67 sites in North America (including 17 sites in the Rocky Mountain region).…”

Section: Observationsmentioning

confidence: 99%

“…4.1), BC mass mixing ratios in the snow are not overall underestimated. In our study, we calibrate the observational data of Doherty et al (2014) by using a correction factor based on the comparison of ISSW and SP2, assuming that SP2 can more accurately measure the mass mixing ratio of BC compared to ISSW (Doherty et al, 2016). However, although SP2 can provide a direct measurement of BC, SP2 may underestimate the real amount of BC-in-snow mass when BC is attached to larger particles (e.g., dust and sea salt) or aggregates to large sizes in snow due to the size range (e.g., ∼ 0.08-0.7 µm) limitations in SP2 .…”

Section: Aerosol-in-snow Concentrationsmentioning

confidence: 99%

“…They used an integrating sphere-integrating sandwich (ISSW) spectrophotometer to estimate the C BC over 67 sites in North America (including 17 sites in the Rocky Mountain region). Observed C BC by Doherty et al (2014) was recorded on a single day. Doherty et al (2016) further provided the temporal Table 2.…”

Section: Observationsmentioning

confidence: 99%

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Impacts of absorbing aerosol deposition on snowpack and hydrologic cycle in the Rocky Mountain region based on variable-resolution CESM (VR-CESM) simulations

Liu

Lin

et al. 2018

Atmos. Chem. Phys.

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Abstract. The deposition of light-absorbing aerosols (LAAs), such as black carbon (BC) and dust, onto snow cover has been suggested to reduce the snow albedo and modulate the snowpack and consequent hydrologic cycle. In this study we use the variable-resolution Community Earth System Model (VR-CESM) with a regionally refined highresolution (0.125 • ) grid to quantify the impacts of LAAs in snow in the Rocky Mountain region during the period 1981-2005. We first evaluate the model simulation of LAA concentrations both near the surface and in snow and then investigate the snowpack and runoff changes induced by LAAs in snow. The model simulates similar magnitudes of near-surface atmospheric dust concentrations as observations in the Rocky Mountain region. Although the model underestimates near-surface atmospheric BC concentrations, the model overestimates BC-in-snow concentrations by 35 % on average. The regional mean surface radiative effect (SRE) due to LAAs in snow reaches up to 0.6-1.7 W m −2 in spring, and dust contributes to about 21-42 % of total SRE. Due to positive snow albedo feedbacks induced by the LAA SRE, snow water equivalent is reduced by 2-50 mm and snow cover fraction by 5-20 % in the two regions around the mountains (eastern Snake River Plain and southwestern Wyoming), corresponding to an increase in surface air temperature by 0.9-1.1 • C. During the snow melting period, LAAs accelerate the hydrologic cycle with monthly runoff increases of 0.15-1.00 mm day −1 in April-May and reductions of 0.04-0.18 mm day −1 in June-July in the mountainous regions. Of all the mountainous regions, the Southern Rockies experience the largest reduction of total runoff by 15 % during the later stage of snowmelt (i.e., June and July). Compared to previous studies based on field observations, our estimation of dust-induced SRE is generally 1 order of magnitude smaller in the Southern Rockies, which is ascribed to the omission of larger dust particles (with the diameter > 10 µm) in the model. This calls for the inclusion of larger dust particles in the model to reduce the discrepancies. Overall these results highlight the potentially important role of LAA interactions with snowpack and the subsequent impacts on the hydrologic cycles across the Rocky Mountains.

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Section: Observationsmentioning

confidence: 99%

Section: Observationsmentioning

confidence: 99%

Section: Aerosol-in-snow Concentrationsmentioning

confidence: 99%

Section: Observationsmentioning

confidence: 99%

See 2 more Smart Citations

Impacts of absorbing aerosol deposition on snowpack and hydrologic cycle in the Rocky Mountain region based on variable-resolution CESM (VR-CESM) simulations

Liu

Lin

et al. 2018

Atmos. Chem. Phys.

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“…This could be a serious disadvantage since paleoclimate data indicate significant increases in aeolian dust deposition during glacial times, especially along the southern margins of the NH ice sheets (Kohfeld and Harrison, 2001;Mahowald et al, 2006). Both theoretical analysis (Warren and Wiscombe, 1980;Aoki et al, 2011) and direct measurements (Painter et al, 2010Skiles et al, 2012;Bryant et al, 2013;Doherty et al, 2013Doherty et al, , 2014Gautam et al, 2013) demonstrate that even small amounts of impurities affect the surface albedo significantly. In turn, the results from the SEB simulations show that these changes in albedo might significantly affect the surface mass balance of ice sheets during glacial times (Krinner et al, 2006;Ganopolski et al, 2010) and in future climate change scenarios (Dumont et al, 2014;Goelles et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Comparison of surface mass balance of ice sheets simulated by positive-degree-day method and energy balance approach

Bauer

Ganopolski

2017

Clim. Past

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Abstract. Glacial cycles of the late Quaternary are controlled by the asymmetrically varying mass balance of continental ice sheets in the Northern Hemisphere. Surface mass balance is governed by processes of ablation and accumulation. Here two ablation schemes, the positive-degree-day (PDD) method and the surface energy balance (SEB) approach, are compared in transient simulations of the last glacial cycle with the Earth system model of intermediate complexity CLIMBER-2. The standard version of the CLIMBER-2 model incorporates the SEB approach and simulates ice volume variations in reasonable agreement with paleoclimate reconstructions during the entire last glacial cycle. Using results from the standard CLIMBER-2 model version, we simulated ablation with the PDD method in offline mode by applying different combinations of three empirical parameters of the PDD scheme. We found that none of the parameter combinations allow us to simulate a surface mass balance of the American and European ice sheets that is similar to that obtained with the standard SEB method. The use of constant values for the empirical PDD parameters led either to too much ablation during the first phase of the last glacial cycle or too little ablation during the final phase. We then substituted the standard SEB scheme in CLIMBER-2 with the PDD scheme and performed a suite of fully interactive (online) simulations of the last glacial cycle with different combinations of PDD parameters. The results of these simulations confirmed the results of the offline simulations: no combination of PDD parameters realistically simulates the evolution of the ice sheets during the entire glacial cycle. The use of constant parameter values in the online simulations leads either to a buildup of too much ice volume at the end of glacial cycle or too little ice volume at the beginning. Even when the model correctly simulates global ice volume at the last glacial maximum (21 ka), it is unable to simulate complete deglaciation during the Holocene. According to our simulations, the SEB approach proves superior for simulations of glacial cycles.

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Parameterizations for narrowband and broadband albedo of pure snow and snow containing mineral dust and black carbon

2015

Self Cite

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The reduction of snow spectral albedo by black carbon (BC) and mineral dust, both alone and in combination, is computed using radiative transfer modeling. Broadband albedo is shown for mass fractions covering the full range from pure snow to pure BC and pure dust, and for snow grain radii from 5 μm to 2500 μm, to cover the range of possible grain sizes on planetary surfaces. Parameterizations are developed for opaque homogeneous snowpacks for three broad bands used in general circulation models and several narrower bands. They are functions of snow grain radius and the mass fraction of BC and/or dust and are valid up to BC content of 10 ppm, needed for highly polluted snow. A change of solar zenith angle can be mimicked by changing grain radius. A given mass fraction of BC causes greater albedo reduction in coarse-grained snow; BC and grain radius can be combined into a single variable to compute the reduction of albedo relative to pure snow. The albedo reduction by BC is less if the snow contains dust, a common situation on mountain glaciers and in agricultural and grazing lands. Measured absorption spectra of mineral dust are critically reviewed as a basis for specifying dust properties for modeling. The effect of dust on snow albedo at visible wavelengths can be represented by an "equivalent BC" amount, scaled down by a factor of about 200. Dust has little effect on the near-IR albedo because the near-IR albedo of pure dust is similar to that of pure snow.

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Black carbon and other light‐absorbing particles in snow of central North America

Cited by 100 publications

References 54 publications

Impacts of absorbing aerosol deposition on snowpack and hydrologic cycle in the Rocky Mountain region based on variable-resolution CESM (VR-CESM) simulations

Impacts of absorbing aerosol deposition on snowpack and hydrologic cycle in the Rocky Mountain region based on variable-resolution CESM (VR-CESM) simulations

Comparison of surface mass balance of ice sheets simulated by positive-degree-day method and energy balance approach

Parameterizations for narrowband and broadband albedo of pure snow and snow containing mineral dust and black carbon

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