Li Wenkai, Guo Weidong, Hsu Pang-Chi, Xue Yongkang
Institute for Climate and Global Change Research, School of Atmospheric Sciences, Nanjing University, Nanjing, China.
Joint International Research Laboratory of Atmospheric and Earth System Sciences, Nanjing, China.
Sci Rep. 2016 Jul 28;6:30456. doi: 10.1038/srep30456.
The Tibetan Plateau (TP), known as the third pole of the Earth, has snow cover with intraseasonal to decadal variability that affects weather and climate both inside and outside the TP. However, the factors that generate the TP snow cover (TPSC) anomalies at the intraseasonal time-scale are unclear. This report reveals the influence of the Madden‒Julian oscillation (MJO), which is the most dominant component of the tropical intraseasonal variability, on TPSC. We focus on wintertime snow cover over the central and eastern TP, where the intraseasonal variability is large. TPSC increases/decreases in the MJO phases 8‒1/4-5, when the eastward-propagating MJO suppressed/enhanced convection locates over the Maritime Continent. Such a change in TPSC leads to the most dominant positive/negative anomalies of TPSC in the following phases 2‒3/6‒7 due to the non-significant change of TPSC in these phases. There is anomalous moisture advection over the upstream of the TP caused by MJO-excited large-scale atmospheric circulation. The advection process generates the low-frequency eastward-propagating anomalous water vapour from upstream to the TP that influences precipitation and, eventually, TPSC.
青藏高原（TP）被誉为地球的第三极，其积雪具有从季节内到年代际的变率，影响着青藏高原内外的天气和气候。然而，在季节内时间尺度上产生青藏高原积雪（TPSC）异常的因素尚不清楚。本报告揭示了热带季节内变率的最主要组成部分——马登-朱利安振荡（MJO）对TPSC的影响。我们关注青藏高原中部和东部冬季的积雪情况，这里季节内变率较大。当向东传播的MJO抑制/增强对流位于海洋大陆上空时，TPSC在MJO的第8-1/4-5阶段增加/减少。由于TPSC在这些阶段变化不显著，TPSC的这种变化导致在随后的第2-3/6-7阶段出现最主要的TPSC正/负异常。MJO激发的大尺度大气环流在青藏高原上游引起异常水汽平流。平流过程产生了从上游向青藏高原低频向东传播的异常水汽，影响降水，最终影响TPSC。
