The interplay of dynamic and thermodynamic processes in driving the ice-edge location in the Southern Ocean

• Published in: Annals of Glaciology
• Main Authors: Stevens, RP, Heil, P
• Format: Article in Journal/Newspaper
• Language: English
• Published: Int Glaciol Soc 2011
• Subjects: Earth Sciences; Oceanography; Oceanography not elsewhere classified; Southern Ocean; Annals of Glaciology; Sea ice
• Online Access: http://www.igsoc.org/annals/v52/57/published.html; https://doi.org/10.3189/172756411795931642; http://ecite.utas.edu.au/68737

A stand-alone sea-ice model (CICE4) was used to investigate the physical processesaffecting the ice-edge location. Particular attention is paid to the relative contributions of dynamic andthermodynamic processes in advancing the ice edge equatorward during ice growth. Results from 10years of an 11 year numerical simulation have been verified against satellite observations from 1998 to2007. The autumn advance of the sea-ice edge is primarily due to thermodynamic processes, withsignificant dynamic contributions limited to regions such as 60708 E and 3103408 E. In thedynamically dominated regions, winds with a southerly component cause equatorward ice advectionbut also induce thermodynamic growth of new ice, which occurs well poleward of the 15% iceconcentrationcontour where air temperature is lowest. As the ice moves into warmer water it melts,hence extending equatorward the region with ocean mixed layer at freezing point. This accelerates thenorthward progression of the ice edge and permits thermodynamic ice growth as soon as the airtemperature reaches below the ocean freezing point. In regions where thermodynamic processes aredominant (e.g. 340408 E), maximum ice production occurs just poleward of the 15% ice-concentrationcontour, where thin sea ice is prevalent. In these longitude bands, autumn ice melt is generally absent atthe ice edge due to ineffective equatorward ice advection.