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

Journal Article · 31 August 2018 · Atmospheric Chemistry and Physics (Online)

DOI: https://doi.org/10.5194/acp-18-12683-2018 · OSTI ID:1467846

Xie, Xiaoning  ^[1]; Liu, Xiaodong  ^[2]; Che, Huizheng ^[3]; Xie, Xiaoxun ^[1]; Li, Xinzhou ^[1]; Shi, Zhengguo  ^[1]; Wang, Hongli ^[4]; Zhao, Tianliang ^[5]; Liu, Yangang  ^[6]

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1. Chinese Academy of Sciences (CAS), Xi'an (China). Shaanxi Key Lab. of Accelerator Mass Spectrometry Technology and Application (SKLLQG) and Inst. of Earth Environment
2. Chinese Academy of Sciences (CAS), Xi'an (China). Shaanxi Key Lab. of Accelerator Mass Spectrometry Technology and Application (SKLLQG) and Inst. of Earth Environment; Univ.of Chinese Academy of Sciences (CAS), Beijing (China)
3. Chinese Academy of Meteorological Sciences (CMA), Beijing (China). Key Lab. for Atmospheric Chemistry and Inst. of Atmospheric Composition
4. Shaanxi Radio and TV Univ., Xi'an (China)
5. Nanjing Univ. of Science Information and Technology (China). Key Lab. for Aerosol-Cloud-Precipitation of China Meteorological Administration
6. Brookhaven National Lab. (BNL), Upton, NY (United States). Environmental and Climate Sciences Dept.

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 work 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.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: Office of Science (SC), Biological and Environmental Research (BER). Earth and Environmental Systems Science Division; National Key Research and Development Program of China; Chinese Academy of Sciences (CAS); National Natural Science Foundation of China (NSFC)
• Grant/Contract Number: SC0012704; 2016YFA0601904; XDA20070103; 41690115; 41572150
• OSTI ID: 1467846
• Report Number(s): BNL-208015-2018-JAAM
• Journal Information: Atmospheric Chemistry and Physics (Online), Vol. 18, Issue 17; ISSN 1680-7324
• Publisher: European Geosciences UnionCopyright Statement
• Country of Publication: United States
• Language: English