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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
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Volume 18, issue 17 | Copyright
Atmos. Chem. Phys., 18, 12683-12698, 2018
https://doi.org/10.5194/acp-18-12683-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 31 Aug 2018

Research article | 31 Aug 2018

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

Xiaoning Xie1, Xiaodong Liu1,2, Huizheng Che3, Xiaoxun Xie1, Xinzhou Li1, Zhengguo Shi1, Hongli Wang4, Tianliang Zhao5, and Yangang Liu6 Xiaoning Xie et al.
  • 1SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China
  • 2University of Chinese Academy of Sciences, Beijing 100049, China
  • 3Key Laboratory for Atmospheric Chemistry, Institute of Atmospheric Composition, Chinese Academy of Meteorological Sciences, CMA, Beijing 100081, China
  • 4Shaanxi Radio and TV University, Xi'an 710119, China
  • 5Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Science Information & Technology, Nanjing 210044, China
  • 6Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY 11973-5000, USA

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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This study extends our previous investigation in dust–radiation interactions to investigate SRF and its feedbacks on the regional climate and the dust cycle over east Asia by use of the CAM4-BAM. Our results show that SRF increases the east Asian dust emissions significantly by 13.7 % in the spring, in contrast to −7.6 % of decreased dust emissions by DRF. Hence, a significant feature of SRF on the Tibetan Plateau can create a positive feedback loop to enhance the dust cycle over east Asia.
This study extends our previous investigation in dust–radiation interactions to investigate SRF...
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