Black carbon radiative forcing over the Tibetan Plateau

He, Cenlin; Li, Qinbin; Liou, Kuo‐Nan; Takano, Yoshi; Gu, Yu; Liu, Qi; Mao, Yuhao; Leung, L. Ruby

doi:10.1002/2014gl062191

Cited by 112 publications

(99 citation statements)

References 54 publications

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“…The northern TP sites (LHG and NETP) are influenced mainly by air masses from Central Asia and partly by air masses from Eurasia, which are similar to the sources of dust reaching the TP (e.g., Zhang et al, 2016). These results are also consistent with those of He et al (2014), Kopacz et al (2011), andLu et al (2012), who modeled contributions of BC emissions in the same re- gion. In the central (TGL and NMC) and southern region (MYL and SETP) of the TP, the air masses originate mainly from Central and South Asia.…”

Section: Distributions Of Lapssupporting

confidence: 82%

“…BC in the atmosphere is mixed with OC and inorganic salts during aging enhancing its absorption (Gustafsson and Ramanathan, 2016). He et al (2014) noted that BC-snow internal mixing increases the albedo forcing by 40-60 % compared with external mixing, and coated BC increases the forcing by 30-50 % compared with uncoated BC aggregates, whereas Koch snowflakes reduce the forcing by 20-40 % relative to spherical snow grains. A lack of OC consideration due to the limitation of the SNICAR model also affected the results in this study.…”

Section: Limitations and Implications For Snow Cover And Glaciers On mentioning

confidence: 99%

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Black carbon and mineral dust in snow cover on the Tibetan Plateau

et al. 2018

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Abstract. Snow cover plays a key role for sustaining ecology and society in mountainous regions. Light-absorbing particulates (including black carbon, organic carbon, and mineral dust) deposited on snow can reduce surface albedo and contribute to the near-worldwide melting of snow and ice. This study focused on understanding the role of black carbon and other water-insoluble light-absorbing particulates in the snow cover of the Tibetan Plateau (TP). The results found that the black carbon, organic carbon, and dust concentrations in snow cover generally ranged from 202 to 17 468 ng g −1 , 491 to 13 880 ng g −1 , and 22 to 846 µg g −1 , respectively, with higher concentrations in the central to northern areas of the TP. Back trajectory analysis suggested that the northern TP was influenced mainly by air masses from Central Asia with some Eurasian influence, and air masses in the central and Himalayan region originated mainly from Central and South Asia. The relative biomassburning-sourced black carbon contributions decreased from ∼ 50 % in the southern TP to ∼ 30 % in the northern TP. The relative contribution of black carbon and dust to snow albedo reduction reached approximately 37 and 15 %, respectively. The effect of black carbon and dust reduced the snow cover duration by 3.1 ± 0.1 to 4.4 ± 0.2 days. Meanwhile, the black carbon and dust had important implications for snowmelt water loss over the TP. The findings indicate that the impacts of black carbon and mineral dust need to be properly accounted for in future regional climate projections, particularly in the high-altitude cryosphere.

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Section: Distributions Of Lapssupporting

confidence: 82%

Section: Limitations and Implications For Snow Cover And Glaciers On mentioning

confidence: 99%

Black carbon and mineral dust in snow cover on the Tibetan Plateau

et al. 2018

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“…Note that the SNICAR model we use assumes spherical snow grains and aerosolsnow external mixing for the calculation of snowpack optical properties (Flanner et al, 2007;Oleson et al, 2010). Recent studies have shown that non-spherical snow grains play a critical role in snow albedo calculations and decrease the snow albedo reductions included by LAAs compared with spherical snow grains (e.g., Liou et al, 2014;Dang et al, 2016;He et al, 2014He et al, , 2017. Nonetheless, the knowledge of snow grain shape evolution is limited and thus spherical snow grains are assumed.…”

Section: Model and Experimental Designmentioning

confidence: 99%

“…Nonetheless, the knowledge of snow grain shape evolution is limited and thus spherical snow grains are assumed. Studies have also shown the significant enhancement of solar radiation absorption with larger snow albedo reductions by aerosol-snow internal mixing compared to aerosol-snow external mixing (e.g., Flanner et al, 2012;He et al, 2014;Liou et al, 2014). However, without considering aerosol-snow internal mixing, the SNICAR model we use assumes absorption-enhancing sulfate coatings to hydrophilic BC, which can mimic BC coatings by snow and compensate for the neglect of the absorption enhancement by aerosol-snow internal mixing (Flanner et al, 2007.…”

Section: Model and Experimental Designmentioning

confidence: 99%

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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“…Ice crystal habit influences the spectral albedo but this effect is not fully understood yet (e.g. Libois et al, 2013;Kokhanovsky and Zege, 2004;Malinka, 2014;Liou et al, 2014;He et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

In situ continuous visible and near-infrared spectroscopy of an alpine snowpack

Dumont¹,

et al. 2017

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Abstract. Snow spectral albedo in the visible/near-infrared range has been continuously measured during a winter season at Col de Porte alpine site (French Alps; 45.30 • N, 5.77 • E; 1325 m a.s.l.). The evolution of such alpine snowpack is complex due to intensive precipitation, rapid melt events and Saharan dust deposition outbreaks. This study highlights that the resulting intricate variations of spectral albedo can be successfully explained by variations of the following snow surface variables: specific surface area (SSA) of snow, effective light-absorbing impurities content, presence of liquid water and slope. The methodology developed in this study disentangles the effect of these variables on snow spectral albedo. The presence of liquid water at the snow surface results in a spectral shift of the albedo from which melt events can be identified with an occurrence of false detection rate lower than 3.5 %. Snow SSA mostly impacts spectral albedo in the near-infrared range. Impurity deposition mostly impacts the albedo in the visible range but this impact is very dependent on snow SSA and surface slope. Our work thus demonstrates that the SSA estimation from spectral albedo is affected by large uncertainties for a tilted snow surface and medium to high impurity contents and that the estimation of impurity content is also affected by large uncertainties, especially for low values below 50 ng g −1 black carbon equivalent. The proposed methodology opens routes for retrieval of SSA, impurity content, melt events and surface slope from spectral albedo. However, an exhaustive accuracy assessment of the snow black properties retrieval would require more independent in situ measurements and is beyond the scope of the present study. This time series of snow spectral albedo nevertheless already provides a new insight into our understanding of the evolution of snow surface properties.

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Black carbon radiative forcing over the Tibetan Plateau

Cited by 112 publications

References 54 publications

Black carbon and mineral dust in snow cover on the Tibetan Plateau

Black carbon and mineral dust in snow cover on the Tibetan Plateau

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

In situ continuous visible and near-infrared spectroscopy of an alpine snowpack

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