Contrasting sea ice drift and deformation between winter and spring in the Antarctic marginal ice zone
Abstract. Two ensembles of buoys, deployed in the north-eastern Weddell Sea region of the Southern Ocean, are analysed to characterise the dynamics driving sea ice drift and deformation during the winter-growth and the spring-retreat seasons of 2019. The results show that although the two buoy arrays were deployed within the same region of ice-covered ocean, their trajectory patterns were vastly different. This indicates a varied response of sea ice in each season to the local winds and currents. Analyses of the winter data showed that the Antarctic Circumpolar Current modulated the drift near the sea ice edge. This led to a highly energetic and mobile ice cover, characterised by free-drift conditions. The resulting drift and deformation were primarily driven by large-scale atmospheric forcing, with negligible contributions due to the wind-forced inertial response. For this highly advective coupled ice-ocean system, ice drift and deformation linearly depends on atmospheric forcing. On the other hand, the drift in spring was governed by the inertial response as increased air temperatures caused the ice cover to melt and break up, within this less advective ice-ocean system. Moreover, the deformation spectra indicate a strong de-coupling to large-scale atmospheric forcing. Analysis, extended to include the datasets of deformation in different regions around Antarctica, indicates that for similar spatial scales the magnitude of deformation may vary between seasons, regions and the proximity to the sea ice edge and the coastline.
Ashleigh Womack et al.
Status: final response (author comments only)