Dissolved Oxygen, NO and PO as tracers for Ross Sea Ice Shelf Water overflow

Abstract

A mesoscale experiment was conducted in the Ross Sea near the shelf break in summer 1997–98 within the framework of the activities of the CLIMA Project of the Italian National Program for Antarctic Research (PNRA), focus on study the shelf—slope interaction between the shelf waters and the CDW in correspondence of the Antarctic Slope Front. This paper deals with the dissolved oxygen distribution and with the application of conservative tracers NO and PO related to the physical variables, improving understanding of mixing processes study in correspondence of the shelf break. Experimental data showed the presence of both Ice Shelf Water overflowing the shelf and Circumpolar Deep Water intruding onto the shelf. Dissolved Oxygen (DO), NO and PO resulted useful as chemical tracers in outlining the mixing processes and bottom water formation spreading off continental shelf break of the Ross Sea, in which seems to be evidence that ISW plays an important role. In fact, a plume of ISW was observed flowing down the continental slope to the deep ocean. From chemical tracers we estimate its magnitude to be about 0.4 ± 0.2 Sv.