The interdecadal changes in the mechanisms accounting for the interannual variation in autumn snow cover over the central eastern Tibetan Plateau (TP) are investigated in this study. An autumn snow index is constructed by area averaging the snow cover over the central eastern TP. The snow index changed from a predominantly negative phase to a positive phase in 1995. Then, the data were divided into two subperiods, 1979–1994 (P1) and 1995–2017 (P2), and the differences in the mechanisms accounting for the variation in autumn snow cover were compared between P1 and P2. An analysis of the local process shows that the autumn snow cover variations over the central eastern TP are caused by snowfall from both autumn and late summer. The autumn snow cover variation over the central eastern TP imposed more significant atmospheric cooling effects during P1 than P2. During P2, except for the local process, the interannual variation in autumn snow cover in the central eastern TP is also affected by atmospheric circulation anomalies originating from the upstream North Atlantic Ocean. During P2, snow‐related North Atlantic sea surface temperature (SST) anomalies (SSTA) can induce a wave train‐like atmospheric pattern that propagates eastward across the Eurasian continent and reaches the TP. Further analysis shows that this wave train‐like atmospheric pattern over the midlatitude Eurasian continent mainly obtains energy from climatological mean flow through baroclinic energy conversion. In contrast, during P1, the North Atlantic SSTA‐related atmospheric circulation pattern tends to propagate northeastward and cannot contribute to the variation in autumn snow cover over the central eastern TP.

中文翻译：

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1990年代中期青藏高原中部秋季积雪年际变化的年代际变化

本文研究了青藏高原东部中部秋季积雪年际变化机理的年代际变化。秋季降雪指数是通过对东部TP中部积雪的平均面积来构建的。1995年的降雪指数从主要为负变到了正。然后，数据被分为两个子时期，1979-1994年（P1）和1995-2017年（P2），其变化机制解释了差异。比较了P1和P2在秋季积雪情况。对当地过程的分析表明，TP东部中部的秋季积雪变化是由秋季和夏末的降雪引起的。P1东部中部的秋季积雪变化在P1期间比P2施加了更大的大气降温效果。在P2期间，除局部过程外，TP东部中部的秋季积雪的年际变化也受到源自北大西洋上游的​​大气环流异常的影响。在P2期间，与雪有关的北大西洋海表温度（SST）异常（SSTA）可以诱发类似于波列的大气模式，该模式向东传播，穿过欧亚大陆并到达TP。进一步的分析表明，中亚欧亚大陆上这种波状大气模式主要是通过斜压能量转换从气候平均流量中获取能量。相反，在P1期间，