Springtime winds drive Ross Sea ice variability and change in the following autumn

• Main Authors: Holland, Marika M, Landrum, Laura, Raphael, Marilyn, Stammerjohn, Sharon
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: eScholarship, University of California 2017
• Subjects: Earth Sciences; Oceanography; Physical Geography and Environmental Geoscience; Climate Change Science; Climate Action; Antarc*; Antarctic; Ross Sea; Sea ice
• Online Access: https://escholarship.org/uc/item/1v01f1s5

Autumn sea ice trends in the western Ross Sea dominate increases in Antarctic sea ice and are outside the range simulated by climate models. Here we use a number of independent data sets to show that variability in western Ross Sea autumn ice conditions is largely driven by springtime zonal winds in the high latitude South Pacific, with a lead-time of 5 months. Enhanced zonal winds dynamically thin the ice, allowing an earlier melt out, enhanced solar absorption, and reduced ice cover the next autumn. This seasonal lag relationship has implications for sea ice prediction. Given a weakening trend in springtime zonal winds, this lagged relationship can also explain an important fraction of the observed sea ice increase. An analysis of climate models indicates that they simulate weaker relationships and wind trends than observed. This contributes to weak western Ross Sea ice trends in climate model simulations.Antarctic seaice extent continues to increase, with autumn seaice advances in the western Ross Sea particularly anomalous. Here, based on analysis of independent datasets, the authors show that springtime zonal winds in the high latitude South Pacific drive western Ross Sea autumn sea ice conditions.