Influence of Tibetan Plateau Snow Cover on East Asian Atmospheric Circulation at Medium-Range Time Scales


Nature Communications (Influence Factors 12.353) recently published a paper titled Influence of Tibetan Plateau snow cover on East Asian atmospheric circulation at medium-range time scales by Professor Weidong Guo's Research Group.

This paper reveals the influence of fast variability of Tibetan Plateau snow cover (TPSC) on the atmospheric circulation at medium-range time scales, enhances our understanding of the influence of TPSC at multiple time scales and hopes to bring attention to the fast daily-subseasonal variability of TPSC and its weather and climate effect.

Snow cover is a special atmospheric underlying surface, whose albedo reaches 0.8 compared with 0.2 of surface and grassland albedo. Snow cover changes the energy allocation via its high albedo characteristics and affects the weather and climate process Known as the third pole in the world, the Tibetan Plateau (TP) has a higher snow cover rate due to its high elevation and freezing temperature. The study over a century shows that TPSC remarkably affects the Asian climate including China at interannual and decadal time scales.

At the daily-subseasonal fast time scales ( less than 90-day variability as revealed by daily data), TPSC often changes fast. The fast variability of TPSC accounts for 66 percent of the total variability. For example, a wide-range fast snow cover changes happened over TP from February 15 to 25, 2017: in only ten days, TPSC changes fast from less coverage (Fig. 1a) to more coverage (Fig. 1b). Quick snow cover change would inevitably lead to large-scale TP surface albedo change and affect later atmospheric circulation via surface energy balance change. Specifically, the anomalous TPSC directly affects downstream upper-level atmospheric circulation (Fig. 2). The positive anomalous westerlies reach the EAJS core region at lag 5-6 days (Fig. 2c). Especially the East Asia atmospheric circulation system – the intensity of upper level westerly jet stream (EAJS) is affected by TPSC thermodynamic disturbance and generates medium variability. This response process of downstream upper-level atmospheric circulation is at an approximate 3-8 days lag, which falls in the medium range.

The first author is Dr. Wenkai Li (who now works at Nanjing University of Information Science & Technology) and Weidong Guo is the corresponding author. Co-authors include Dr. Bo Qiu of Nanjing University, Professor Yongkang Xue of University of California, Los Angeles, and Proffessor Bangqi Xu and Professor Jiangfeng Wei from Nanjing University of Information Science & Technology. The study is supported by Strategic Priority Research Program (A) of the Chinese Academy of Sciences and National Natural Science Foundation of China. This research is also supported by Institute for Climate and Global Change Research, Joint International Research Laboratory of Atmospheric and Earth System Sciences, and Jiangsu Collaborative Innovation Center for Climate Change.

Attached figure:

Figure1: TPSC changes observed by MODIS Terra

Figure2: Response of the upper-level atmospheric circulation (300-hPa zonal wind; the unit is m s−1) over TPSC fast variability as revealed by regional climate model.

Paper related information:

LI Wenkai, GUO Weidong (*), QIU Bo, XUE Yongkang, HSU Pang-Chi, WEI Jiangfeng. (2018)Influence of Tibetan Plateau snow cover on East Asian atmospheric circulation at medium-range time scales, Nature Communications, 9: 4243, doi: 10.1038/s41467-018-06762-5.

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