The Pacific zonal asymmetry and its influence on Southern Hemisphere sea ice variability

• Published in: Antarctic Science
• Main Authors: Hobbs, W.R., Raphael, M.N.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2010
• Subjects: Antarctic; Southern Ocean; Ross Sea; Drake Passage; Pacific; New Zealand; Weddell; Antarc*; Antarctic Science; Sea ice
• Online Access: http://dx.doi.org/10.1017/s0954102010000283; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102010000283

Abstract At monthly and annual timescales, the zonally asymmetric circulation over the Southern Ocean is dominated by two quasi-stationary anticyclones: a western anticyclone approximately located south of New Zealand, and an eastern anticyclone located over the Drake Passage region. In this research their influence on late 20th century Antarctic sea ice is explored. During early winter, sea ice in the Weddell, Amundsen and Bellingshausen seas is influenced by the location of the east anticyclone. During late winter, the strength and location of the west anticyclone influences sea ice primarily in the Ross and Amundsen seas. The anticyclones have some effect on wind-driven sea ice motion, but the primary mechanism explaining their link to sea ice appears to be meridional atmospheric thermal advection. A western shift in the west anticyclone may be partly responsible for observed increases in ice cover in the Ross Sea over the late 20th century, but there is little evidence in existing data to support a link between the east anticyclone and observed sea ice trends.