Detecting the contributions of internal variability and external forcing to the evolution of surface air temperature (SAT) trend at regional scales is a challenge. Based on the observations and large-ensemble simulations of climate models, we estimate the contribution of the internal and forced components to the evolution of East Asian winter land SAT (EAWT) during 1961–2018. Although the external forcing induced EAWT trends show a slow increase, both the total and internally generated EAWT trends exhibit a decrease with the extension of the time period, suggesting a critical role of internal variability in the evolution of the EAWT trends. The internal variability contributes to about 70% of total EAWT trends during 1961–1995. With the extension of the time period, the contribution of internal variability decreases, whereas the contribution of external forcing gradually grows to dominate the EAWT trends. Based on the dynamical adjustment method, we identify that the internal dynamics and forced thermodynamics account for a majority of internal and forced EAWT variations, respectively. We further identify that the multidecadal fluctuation of internal component of autumn Arctic sea ice is a critical precursor of the internal variability, especially the internal dynamically induced EAWT variations, through triggering a meridional stationary Rossby wave response in the following boreal winter. Our findings provide an insight into the understanding of the present and future climate change over East Asia.

在区域尺度上检测内部变率和外部强迫对地表气温（SAT）趋势演变的贡献是一个挑战。基于对气候模型的观测和大集合模拟，我们估计了1961-2018年内部和强迫成分对东亚冬季陆地SAT（EAWT）演变的贡献。尽管外部强迫诱发的EAWT趋势显示出缓慢的增长，但是总的和内部产生的EAWT趋势都随着时间的延长而减小，这表明内部可变性在EAWT趋势的演变中起着至关重要的作用。在1961-1995年期间，内部可变性约占EAWT总趋势的70％。随着时间周期的延长，内部变异性的影响减小，而外部强迫的贡献逐渐增长，从而主导了EAWT趋势。基于动态调整方法，我们确定内部动力学和强制热力学分别占内部和强制EAWT变化的大部分。我们进一步发现，秋季北极海冰内部分量的多年代际波动是内部可变性的关键先兆，尤其是内部动态诱发的EAWT变化，这是通过在随后的寒冬触发子午线平稳的Rossby波响应而引起的。我们的发现为了解东亚当前和未来的气候变化提供了见识。我们发现内部动力学和强迫热力学分别占内部和强迫EAWT变化的大部分。我们进一步发现，秋季北极海冰内部分量的多年代际波动是内部可变性的关键先兆，尤其是内部动态诱发的EAWT变化，这是通过在随后的寒冬触发子午线平稳的Rossby波响应而引起的。我们的发现为了解东亚当前和未来的气候变化提供了见识。我们发现内部动力学和强迫热力学分别占内部和强迫EAWT变化的大部分。我们进一步发现，秋季北极海冰内部分量的多年代际波动是内部可变性的关键先兆，尤其是内部动态诱发的EAWT变化，这是通过在随后的寒冬触发子午线平稳的Rossby波响应而引起的。我们的发现为了解东亚当前和未来的气候变化提供了见识。在接下来的寒冬触发子午线平稳的Rossby波响应。我们的发现为了解东亚当前和未来的气候变化提供了见识。在接下来的寒冬触发子午线平稳的Rossby波响应。我们的发现为了解东亚当前和未来的气候变化提供了见识。