On the origin of discrepancies between observed and simulated memory of Arctic Sea ice

• Published in: Geophysical Research Letters
• Main Authors: Giesse, C., Notz, D., Baehr, J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Arctic; Sea ice
• Online Access: http://hdl.handle.net/21.11116/0000-0008-D546-9; http://hdl.handle.net/21.11116/0000-0008-D54B-4

To investigate the inherent predictability of sea ice and its representation in climate models, we compare the seasonal-to-interannual memory of Arctic sea ice as given by lagged correlations of sea-ice area anomalies in large model ensembles (Max Planck Institute Grand Ensemble and Coupled Model Intercomparison Project phase 6) and multiple observational products. We find that state-of-the-art climate models significantly overestimate the memory of pan-Arctic sea-ice area from the summer months into the following year. This cannot be explained by internal variability. We further show that the observed summer memory can be disentangled regionally into a reemergence of positive correlations in the perennial ice zone and negative correlations in the seasonal ice zone; the latter giving rise to the discrepancy between observations and model simulations. These findings could explain some of the predictability gap between potential and operational forecast skill of Arctic sea-ice area identified in previous studies.