Two Atmospheric Responses to Winter Sea Ice Decline Over the Barents-Kara Seas

The intraseasonal atmospheric responses to winter sea ice decline over the Barents-Kara Seas are examined by dividing rapid sea ice decline events into two categories, based on the direction (upward vs. downward) of the anomalous surface turbulent heat flux (ASTHF) after the sea ice loss. The upward ASTHF events, which could potentially have a large impact on the overlying atmosphere, are characterized by anomalously negative total column water and surface air temperature minus skin temperature, and anomalously positive surface wind speed following the sea ice loss. The downward ASTHF events show opposite features. Both types of events are linked to the Madden-Julian Oscillation and subsequent circulation anomalies. This result indicates that on the intraseasonal time scale, not all sea ice decline events influence the atmosphere, and caution is called for when designing transient model experiments using observed sea ice decline. Plain Language Summary Wintertime Arctic sea ice has undergone a rapid decline during the past few decades. The question of whether sea ice decline has an influence on the atmosphere is explored at intraseasonal time scales during the winter season by dividing rapid sea ice decline events into two categories based on the direction (upward vs. downward) of the anomalous surface turbulent heat flux (ASTHF) over the Barents-Kara Seas after sea ice loss. Only the upward ASTHF events have the potential to have a large impact on the atmosphere. This difference in the direction of the ASTHF after the sea ice loss is found to be linked to different properties of surface air temperature, skin temperature, moisture and wind speed over the BKS for the two types of events. Furthermore, it is found that the direction of the ASTHF is also related to the tropical Madden-Julian Oscillation and wind anomalies that follow. Modeling studies often employ observed/simulated sea ice loss as a boundary forcing to evaluate their impact on the atmosphere. The result of this study can be used to refine such a modeling approach.