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

Zhang, Yulan; Kang, Shichang; Sprenger, Michael; Cong, Zhiyuan; Gao, Tanguang; Li, Chaoliu; Tao, Shu; Li, Xiaofei; Zhong, Xianqiong; Xu, Min; Meng, Wenjun; Neupane, Bigyan; Qin, Xiang; Sillanpää, Mika

doi:10.5194/tc-12-413-2018

Cited by 105 publications

(102 citation statements)

References 122 publications

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“…Radiative forcing is largely in the 0.3–4.0 W·m −2 range in Europe and North America based on observations and model simulations (Dang et al, 2017; Flanner et al, 2009; Gabbi et al, 2015; Rowe et al, 2019; Wu et al, 2018). Radiative forcing varies over the 1.5–25 W·m −2 range on the Tibetan Plateau (Jacobi et al, 2015; Kaspari et al, 2014; Kopacz et al, 2011; Zhang et al, 2017, 2018). Radiative forcing ranges from 1–7 W·m −2 in northwestern China to 3.0–20 W·m −2 in northeastern China (Dang et al, 2017; Zhao et al, 2014).…”

Section: Resultsmentioning

confidence: 99%

Albedo of Black Carbon‐Contaminated Snow Across Northwestern China and the Validation With Model Simulation

Shi

Zhou

et al. 2020

JGR Atmospheres

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Light-absorbing particles in snow can significantly reduce the snow albedo. Quantification of the influence of black carbon (BC), one of the most important light-absorbing particles, on snow albedo is essential for understanding the budgets of solar radiation on snow-covered areas. We measured BC concentration in snow at 28 sites and snow albedo at 18 sites in a vast region across northwestern China in January 2018. The BC concentration was in a wide range of 40-1,850 ng g −1 . The presence of the BC reduced the snow albedo by 0.01-0.20 at the visible wavelength band (400-750 nm). The reduction differed from sites to sites with large values close to industrial areas that are characterized by high pollutants emission. Albedos simulated with a Snow, Ice, and Aerosol Radiation model based on the measured BC agreed well with the measured albedos, with the deviation within ±0.03 and the average underestimation of <0.002. It worth noting that the retrieved optical effective snow grain radius was the key factor in snow albedo calculation. The BC-induced radiative forcing was estimated to be 0.2-6.9 W m −2 , indicating strong acceleration of snowmelt due to BC in northwestern China. All obtained data are extremely valuable for climate model validation associated with the albedo of BC-contaminated snow cover.Plain Language Summary Snow cover on the Earth system is one of the most reflective surfaces and plays a crucial role in the budget of solar radiation energy in the atmosphere. Studies with controlled experiments and model simulations have shown the reductive effect of BC pollution on snow albedo, but the reduction has rarely been assessed with in situ observations. For the first time, we measured both snow albedo and BC concentration in snow in a vast area across northwestern China. Results show a good correlation between the two variables, which is consistent with previous studies, that is, the more BC, the larger reduction. We found that the retrieved optical effective snow grain radius was the key factor to enhance the albedo simulation. We also estimated the radiative forcing of BC in snow and got a nonignorant absorptive effect, which indicates a possible accelerated snowmelt. All the data are extremely valuable for climate model validation associated with the reflection by BC-contaminated snow cover.

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Section: Resultsmentioning

confidence: 99%

Albedo of Black Carbon‐Contaminated Snow Across Northwestern China and the Validation With Model Simulation

Shi

Zhou

et al. 2020

JGR Atmospheres

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“…Fast et al (2006) and Barnard et al (2010) provide detailed descriptions of the computation of aerosol optical properties such as extinction coefficient, single-scattering albedo (SSA) and asymmetry factor in WRF-Chem. Following Zhao et al (2011Zhao et al ( , 2013b, aerosol radiative feedback is coupled with the Rapid Radiative Transfer Model (RRTMG) (Mlawer et al, 1997), and the direct radiative forcing of individual aerosol species in the atmosphere are diagnosed. Aerosol-cloud interactions are included in the model following Gustafson et al (2007).…”

Section: Coupled Wrf-chem-clm-snicar Model Descriptionmentioning

confidence: 99%

Impact of light-absorbing particles on snow albedo darkening and associated radiative forcing over high-mountain Asia: high-resolution WRF-Chem modeling and new satellite observations

et al. 2019

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Light-absorbing particles (LAPs), mainly dust and black carbon, can significantly impact snowmelt and regional water availability over high-mountain Asia (HMA). In this study, for the first time, online aerosol-snow interactions are enabled and a fully coupled chemistry Weather Research and Forecasting (WRF-Chem) regional model is used to simulate LAP-induced radiative forcing on snow surfaces in HMA at relatively high spatial resolution (12 km, WRF-HR) compared with previous studies. Simulated macro-and microphysical properties of the snowpack and LAP-induced snow darkening are evaluated against new spatially and temporally complete datasets of snow-covered area, grain size, and impurity-induced albedo reduction over HMA. A WRF-Chem quasi-global simulation with the same configuration as WRF-HR but a coarser spatial resolution (1 • , WRF-CR) is also used to illustrate the impact of spatial resolution on simulations of snow properties and aerosol distribution over HMA. Due to a more realistic representation of terrain slopes over HMA, the higher-resolution model (WRF-HR) shows significantly better performance in simulating snow area cover, duration of snow cover, snow albedo and snow grain size over HMA, as well as an evidently better atmospheric aerosol loading and mean LAP concentration in snow. However, the differences in albedo reduction from model and satellite retrievals is large during winter due to associated overestimation in simulated snow fraction. It is noteworthy that Himalayan snow cover has high magnitudes of LAP-induced snow albedo reduction (4 %-8 %) in pre-monsoon seasons (both from WRF-HR and satellite es-timates), which induces a snow-mediated radiative forcing of ∼ 30-50 W m −2 . As a result, the Himalayas (specifically the western Himalayas) hold the most vulnerable glaciers and mountain snowpack to the LAP-induced snow darkening effect within HMA. In summary, coarse spatial resolution and absence of snow-aerosol interactions over the Himalayan cryosphere will result in significant underestimation of aerosol effects on snow melting and regional hydroclimate.

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“…A large amount of desert dust from eastern Asian arid and semiarid regions is emitted into the atmosphere, which can be carried over the wide downwind regions, including eastern China and the Pacific Ocean, and also deposited in snow over the Tibetan Plateau (Wake et al, 1994;Zhang et al, 1997;Zhao et al, 2006). The dust can significantly affect the global and regional energy balance, climate and hydrological cycle by dust direct radiative forcing and dust-in-snow radiative forcing (Ramanathan et al, 2001;Shao et al, 2011;Mahowald et al, 2014;Huang et al, 2014;Qian et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Radiative feedbacks of dust in snow over eastern Asia in CAM4-BAM

et al. 2018

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Abstract. Dust in snow on the Tibetan Plateau (TP) could reduce the visible snow albedo by changing surface optical properties and removing the snow cover through increased snowmelt, which leads to a significant positive radiative forcing and remarkably alters the regional energy balance and the eastern Asian climate system. This study extends our previous investigation in dust–radiation interactions to investigate the dust-in-snow radiative forcing (SRF) and its feedbacks on the regional climate and the dust cycle over eastern Asia through the use of the Community Atmosphere Model version 4 with a Bulk Aerosol Model parameterizations of the dust size distribution (CAM4-BAM). Our results show that SRF increases the eastern Asian dust emissions significantly by 13.7 % in the spring, countering a 7.6 % decrease in the regional emissions by the dust direct radiative forcing (DRF). SRF also remarkably affects the whole dust cycle, including transport and deposition of dust aerosols over eastern Asia. The simulations indicate an increase in dust emissions of 5.1 %, due to the combined effect of DRF and SRF. Further analysis reveals that these results are mainly due to the regional climatic feedbacks induced by SRF over eastern Asia. By reducing the snow albedo over the TP, the dust in snow mainly warms the TP and influences its thermal effects by increasing the surface sensible and latent heat flux, which in turn increases the aridity and westerly winds over northwestern China and affects the regional dust cycle. Additionally, the dust in snow also accelerates the snow-melting process, reduces the snow cover and then expands the eastern Asian dust source region, which results in increasing the regional dust emissions. Hence, a significant feature of SRF on the TP is the creation of a positive feedback loop that affects the dust cycle over eastern Asia.

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

Cited by 105 publications

References 122 publications

Albedo of Black Carbon‐Contaminated Snow Across Northwestern China and the Validation With Model Simulation

Albedo of Black Carbon‐Contaminated Snow Across Northwestern China and the Validation With Model Simulation

Impact of light-absorbing particles on snow albedo darkening and associated radiative forcing over high-mountain Asia: high-resolution WRF-Chem modeling and new satellite observations

Radiative feedbacks of dust in snow over eastern Asia in CAM4-BAM

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