This study investigates the dynamical mechanism responsible for Arctic mid-to-upper tropospheric warming linked to Arctic sea-ice loss. Using reanalysis and model simulations, the authors demonstrate that Barents-Kara sea-ice loss enhances upward propagating waves, leading to wave convergence anomalies in the sub-polar lower stratosphere and upper troposphere. This results in a clockwise residual overturning anomaly, causing anomalous descent and adiabatic warming in the Arctic mid-to-upper troposphere. Model simulations with suppressed stratospheric variability confirm the crucial role of stratosphere-troposphere coupling in this deep Arctic warming.

Mian Xu, Wenshou Tian, Jiankai Zhang, James A. Screen, Chongyang Zhang, Zhe Wang