Prof Marcello Vichi
Marine Research Institute and Department of Oceanography, University of Cape Town, South Africa

Surfing white waves: impacts of a severe storm on the winter marginal ice zone in the Southern Ocean

The winter marginal ice zone (MIZ) in the Southern Ocean is one of the least explored regions of the world ocean, where synoptic weather, sea-ice and oceanic processes are more tightly interlinked. Remote sensing observations have revealed the large variability of the Southern Ocean sea ice over the past 20 years, and the increased spatial resolution of sensors now allow to capture synoptic patterns in the ice edge. The actual reliability of these data is however not known because of the very few in situ observations particularly during the winter period.

This contribution reports on a process study conducted in July 2017 in the Indian Ocean sector, aimed at studying the winter MIZ, the relation with met-ocean conditions and how they impact navigation performances. The response of the MIZ to a large-scale storm was documented by means of sea-ice observations, ice-drift buoys, wave cameras and the ship-response to vibrations. The sea ice was composed of pancakes of varying dimensions that did not show compaction for more than 150 km into the MIZ.

The preliminary results hint at a coherent large-scale response of the pancake ice field to wind and swell, with 7 m significann wave height and drifts of up to 0.8 m/s, more typical to brash ice conditions rather than the observed semi-consolidated surface. The results are analysed in conjunction with atmospheric reanalyses data and ocean forecasting models to provide insights on the process dynamics and improve future polar predictions in the southern hemisphere.


OBS! Time and Place
Monday March 12th 2018, 13.15
Rossbysalen C609, Arrhenius Laboratory, 6th floor