Received: 29 Mar 2017 – Discussion started: 25 Apr 2017
Abstract. Satellite observations demonstrate Antarctic sea ice extent increased between late-1978 and 2015, with significant spatial and seasonal variability. Late spring retreat off George V Land is a major component of the observed increase, but the paucity of proxy records makes interpretation of trends (and impacts) challenging. Here Earth-system modelling and reanalysis demonstrate tropical Pacific warming can trigger an atmospheric Rossby wave response during the austral spring, delaying sea-ice retreat off George V Land. Our results provide new insights into the spatial and temporal role low latitudes play in Antarctic sea-ice production, drift and ocean circulation on decadal to centennial timescales.
How to cite. Turney, C. S. ~M., Klekociuk, A., Fogwill, C. J., Zunz, V., Goosse, H., Parkinson, C. L., Compo, G., Lazzara, M., Keller, L., Allan, R., Palmer, J. G., Clark, G., and Marzinelli, E.: Brief communication: Changing mid-twentieth century Antarctic sea ice variability linked to tropical forcing, The Cryosphere Discuss. [preprint], https://doi.org/10.5194/tc-2017-51, 2017.
We demonstrate that a mid-twentieth century decrease in geopotential height in the southwest Pacific marks a Rossby wave response to equatorial Pacific warming, leading to enhanced easterly airflow off George V Land. Our results suggest that in contrast to ozone hole-driven changes in the Amundsen Sea, the 1979–2015 increase in sea ice extent off George V Land may be in response to reduced northward Ekman drift and enhanced (near-coast) production as a consequence of low latitude forcing.
We demonstrate that a mid-twentieth century decrease in geopotential height in the southwest...