Influence of Tibetan Plateau snow cover on East Asian atmospheric circulation at medium-range time scales (2018)

promulgator:梁缘published:2018-10-13views:27

The responses of atmospheric variability to Tibetan Plateau (TP) snow cover (TPSC) at seasonal, interannual and decadal time scales have been extensively investigated. However, the atmospheric response to faster subseasonal variability of TPSC has been largely ignored. Li et al. (2018) found that the subseasonal variability of TPSC, as revealed by daily data, is closely related to the subsequent East Asian atmospheric circulation at medium-range time scales (approximately 3–8 days later) during wintertime. TPSC acts as an elevated cooling source in the middle troposphere during wintertime and rapidly modulates the land surface thermal conditions over the TP. When TPSC is high, the upper-level geopotential height is lower, and the East Asia upper-level westerly jet stream is stronger (Figure 1). This finding improves our understanding of the influence of TPSC at multiple time scales. Furthermore, their work highlights the need to understand how atmospheric variability is rapidly modulated by fast snow cover changes.

  Figure 1 The East Asia upper-level westerly jet stream index from observations and numerical experiments. The response of the East Asia upper-level westerly jet stream index to the subseasonal variability of Tibetan Plateau snow cover. The x-axis represents the number of days lagging the start of each event for the composites or the model initial date. The black line and blue line represent the reanalysis/analysis composites and numerical experiments, respectively. The light blue shading represents the range of the East Asia upper-level westerly jet stream index cover index between the 25th and 75th percentile of the numerical experiment ensembles. The unit is m/s.

Li, W., Guo, W. (*), Qiu, B., Xue, Y., Hsu, P.-C. and Wei, J.: Influence of Tibetan Plateau snow cover on East Asian atmospheric circulation at medium-range time scales, Nat. Commun., in press, doi: 10.1038/s41467-018-06762-5, 2018.