The Role of the Stratospheric Pathway in Linking the Arctic Sea Ice Loss to the Midlatitude Circulation in CMIP5 Models

Unprecedented sea ice loss accompanied with amplified warming has been observed over the Arctic in the past few decades. Observational and modeling studies have documented the linkage between the Arctic sea ice and the Northern Hemisphere mid-latitude circulation. However, the dynamical mechanism is not yet fully understood, especially on the role of the stratosphere. In this study, we investigate the role of the stratosphere in linking the sea ice loss in autumn to the mid-latitude circulation in the subsequent winter. Currently we are exploring two groups of models from the Coupled Model Intercomparison Project phase5 (CMIP5) archive, one with well-resolved stratosphere (high-top models) and the other with poorly-resolved stratosphere (low-top models) to distinguish the dynamics of the stratospheric pathway. Our results show that high-top models with well-resolved stratosphere are able to capture the persistent midlatitude circulation response to autumn sea ice loss as that in observations. However, the response in low-top models is weaker and is not as long-lasting. The comparison between high-top and low-top models suggests an important role of the stratospheric pathway. The underlying dynamical mechanism will also be discussed.