A212-0004
Are the Impacts of the Observed Arctic Sea-ice Variability on the Cold Season Atmospheric Circulation Underestimated in AGCM Experiments?

Wednesday, 16 December 2020
Poster
Yu-Chiao Liang1, Claude Frankignoul2, Young-Oh Kwon3, Guillaume Gastineau4, Elisa Manzini5, Gokhan Danabasoglu6, Lingling Suo7, Stephen G Yeager8, Yongqi Gao7, Jisk Jakob Attema9, Annalisa Cherchi10, Rohit Ghosh11, Daniela Matei5, Jennifer Mecking12, Tian Tian13 and Ying Zhang14, (1)Woods Hole Oceanographic Institution, Physical Oceanography, Woods Hole, MA, United States, (2)Sorbonnes Universités LOCEAN, Paris, France, (3)Woods Hole Oceanographic Institution, Physical Oceanography Department, Woods Hole, MA, United States, (4)LOCEAN-IPSL, Paris cedex 05, France, (5)Max Planck Institute for Meteorology, Hamburg, Germany, (6)National Center for Atmospheric Research, Boulder, CO, United States, (7)Nansen Environmental and Remote Sensing Center, Bergen, Norway, (8)NCAR, Oceanography, Boulder, CO, United States, (9)Netherlands eScience Center, Amsterdam, Netherlands, (10)Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy, (11)Max Planck Institute for Meteorology, The Ocean in the Earth System, Hamburg, Germany, (12)University of Southampton, Southampton, United Kingdom, (13)Danish Meteorological Institute, Copenhagen, Denmark, (14)Climate Change Research Center, Beijing, China
Abstract:
To examine the atmospheric responses to Arctic sea-ice variability in the Northern Hemisphere cold season (October to following March), this study uses a coordinated set of large-ensemble experiments of nine atmospheric general circulation models (AGCMs) forced with observed daily-varying sea-ice, sea-surface temperature, and radiative forcings prescribed during the 1979-2014 period, together with a parallel set of experiments where Arctic sea ice is substituted by its climatology. The simulations of the former set reproduce the near-surface temperature trends in reanalysis data, with similar amplitude and geographic distribution. Discrepancies appear in the trends of sea-level pressure and other dynamical components, but the trends of reanalysis data generally lack statistical significance and primarily reflect internal atmospheric variability. The difference between the two sets of experiments allows singling out the effects of Arctic sea-ice loss. The Arctic warming trends are largely due to the sea-ice retreat, and they extend from the surface to the stratosphere. In late winter, sea-ice loss drives a weak negative Arctic Oscillation-like circulation trend and a southward shift of mid-latitude jet. An examination of the co-variability between the Arctic sea ice and atmospheric circulation at interannual timescale indicates that a sea-ice decline in the Barents-Kara Seas tends to be followed by a negative North Atlantic Oscillation-like anomaly, as in reanalysis data. However, the co-variability in the simulations is weaker and only detected in the multi-model mean differences. The results suggest that the AGCMs may underestimate the Arctic sea-ice impacts on the cold season atmospheric circulation, relative to the internal variability. The AGCM results will be compared with corresponding sets of fully coupled simulations to investigate the effect of atmosphere-ocean interaction.
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