Turning the Arctic inside out – a new inverse method for understanding the ocean circulation
The Arctic is a region where waters from elsewhere in the ocean undergo significant transformations due to the formation and melting of sea-ice and interactions with the atmosphere. One way to examine these transformations is in thermohaline coordinates: by categorising water masses according to their temperature and salinity, the complex 3D geographical circulation is much simplified. It then becomes possible to examine the relative roles of different processes driving the circulation. In this seminar, I will describe the development of the Regional Thermohaline Inverse Method (RTHIM), a new inverse method in thermohaline coordinates which can solve the boundary advection and interior mixing of an enclosed volume.
Having validated the method with the NEMO ocean model, it is then applied to observational data to obtain estimates for the actual circulation in the Arctic region. The study is a contribution to OSNAP (the Overturning in the Subpolar North Atlantic Programme), which includes a large mooring array taking observations of the North Atlantic Subpolar Gyre. RTHIM will ultimately be applied to the OSNAP region and will provide us with estimates of the transport through the section covered by the moorings that is independent of the observations, as well as for the interior mixing.