The effect of flow at Maud Rise on the sea-ice cover – numerical experiments

Abstract

The role of seamounts in the formation and evolution of sea ice is investigated in a series of numerical experiments with a coupled sea ice±ocean model. Bottom topography, strati®cation and forcing are con®gured for the Maud Rise region in the Weddell Sea. The speci®c¯ow regime that develops at the seamount as the combined response to steady and tidal forcing consists of free and trapped waves and a vortex cap, which is caused by mean¯ow and tidal¯ow recti®cation. The enhanced variability through tidal motion in particular modi®es the mixed layer above the seamount enough to delay and reduce sea-ice formation throughout the winter. The induced sea-ice anomaly spreads and moves westward and a ects an area of several 100 000 km 2 . Process studies reveal the complex interaction between wind, steady and periodic ocean currents: all three are required in the process of generation of the sea ice and mixed layer anomalies (mainly through tidal¯ow), their detachment from the topography (caused by steady oceanic¯ow) and the westward translation of the sea-ice anomaly (driven by the timemean wind).

Temporal variations and trends of CFC11 and CFC12 surface-water saturations in Antarctic marginal seas: Results of a regional ocean circulation model

“…After the sea ice melted, high CFC fluxes persist (see Section 4.1) until sea ice growth again suppresses the gas exchange. This is confirmed 663 by independent simulations of the complex flow regime at Maud Rise (Beckmann et al, 2001) and by observed upwelling of subsurface water masses (Muench et al, 2001).…”

The sea-ice performance of the Australian climate models participating in the CMIP5

“…In September, the Antarctic sea-ice edge in the ACCESS runs tends to extend too far north as illustrated by the positive sea-ice concentration biases in Figs 5(f) and 5(g). Around Maud Rise, however, negative sea-ice concentration biases along with a deep mixed layer exist consistent with a too convective ocean releasing oceanic heat to melt the ice in winter (Beckmann et al 2001, Sirevaag et al 2010, Marsland et al 2012. CSIRO-Mk3.6 sea-ice concentration biases in September are relatively small with too much sea-ice in the northern Weddell Sea and too little sea-ice in the Amundsen Sea.…”

State of the Climate in 2016

“…This was followed, from 11 to 29 August, by a larger polynya in the Cosmonaut Sea (~40°-50°E, 66°S). Polynyas are thought to recur in these areas due to a combination of oceanic and atmospheric forcing (e.g., Holland 2000; Beckmann et al 2001;Arbetter et al 2004). Analysis within the Southern Ocean section of this chapter (6g) suggests that the Maud Rise polynya in 2016 was probably related to increased deep convection due to the higher-thanaverage salinity in that region.…”