Madden-Julian Oscillation (MJO)作為冬季熱帶大氣季節內振蕩的主要模態，能夠通過與背景場（mean state）間的相互作用🧂，激發大氣遙相關（簡稱MJO-teleconnection）可對中高緯地表氣溫的次季節變率產生重要影響。同時，MJO-teleconnection本身也會受到不同物理因子（如✹：ENSO🕵🏻♀️，IOD，QBO）年際異常的影響🙅🏻♂️。迄今為止，少有研究關註青藏高原積雪的年際變率對其調製作用💇🏼。
沐鸣2的直博生曹璨在吳誌偉教授的指導下，研究了冬季青藏高原積雪的年際信號異常對於東亞地表氣溫次季節變率的調製作用🤵♂️，揭示了高原積雪如何調控MJO-teleconnection這一關鍵物理過程。結果表明，東亞地表氣溫的次季節變率是多尺度間相互作用的結果，高原積雪的年際信號增強，能夠使得東亞次季節尺度的地表氣溫更冷，其對於MJO-teleconnection的調製作用在這一變化中起到了正貢獻。同時，數值試驗表明波源本身的變化有利於次季節尺度的地表氣溫降低🪜，而背景場的變化不利於次季節尺度的地表氣溫降低。
該研究有助於深入理解MJO-teleconnection這一物理過程，研究結果表明考慮高原積雪這一關鍵下墊面因子的強迫作用，有助於提高中高緯地表氣溫的次季節預報技巧🦏。
論文於2022年發表在《Climate Dynamics》期刊上。
論文信息：Cao C.,Zhiwei Wu*2022: Modulation of the Tibetan Plateau snow cover on the interannual variations of the MJO-Related winter surface air temperature anomalies over East Asia. Climate Dynamics, DOI: 10.1007/s00382-022-06275-4
Fig. 1 Composite surface air temperature anomalies (shading, ) in MJO phase 3 for the ETPSC winters (a), RTPSC winters (b) and the climatology (c). The differences between the ETPSC winters and climatology (d), RTPSC winters and climatology (e), and the ETPSC winters and RTPSC (f) winters are shown. Black dots show the significance at the 90% confidence level. The focused region is (35°-45°N，100°-130°E).
Fig. 2 Individual terms of the meridional advection of the temperature (10-6 K/s) averaged in the box region (35°-45°N👩🏿⚕️，100°-130°E) at 1000 hPa (averaged from day -10 to day 0) for (a) the ETPSC (green), the climatology (blue) and the difference (white) for the MJO phase 3, (b) the RTPSC (red) , the climatology (blue) and the difference (white) for the MJO phase 3, (c) the ETPSC (green), the RTPSC (red) and the difference (white) for the MJO phase 3. The asterisk indicates the difference significant at the 90% confidence level.
Fig. 3 Composite geopotential height anomalies (shading, gpm) at 200 and 500 hPa in MJO phase 3 for the ETPSC winters (a, d), RTPSC winters (b, e) and the climatology (c, f). The wave activity fluxes (vectors, m2/s2) at 200 hPa are also shown. The curve shows the geopotential height anomalies significant at 95% confidence level.
