Séminaire
Given the importance of the overturning circulation to global climate, there is a need to improve our understanding of Antarctic Bottom Water (AABW) formation and its sensitivity to change. The AABW has been observed to freshen and decrease in volume over the past few decades. This modelling study focuses on the potential freshening of Dense Shelf Water (DSW), which contributes to the formation of AABW , by increased melting of ice-shelves in response to global warming. Ocean observations show the importance of coastal latent heat polynyas near the Mertz Glacier Tongue (MGT) to the formation of DSW and associated AABW production. A recent modelling study in this region has shown the importance of the polynya activity and ocean/ice-shelf interaction on DSW formation and export. Also, ice shelf melt can be modulated by intrusion of relatively warm Circumpolar Deep Water (CDW) onto the continental shelf which can further freshen DSW . Here, we present preliminary results from idealised numerical experiments designed to test the sensibility of DSW formation to variability in both surface fluxes (polynya activity and sea ice formation rates) and ice shelf melting. This study also shows that the inflow of CDW onto the continental shelf can be related with the strength of the vertical convection within the water column due to the dense water formation by sea ice formation.