Wednesday 25 Oct 2017: Adjoint sensitivity experiments in the Labrador Sea and Southern Ocean
Dan Jones - British Antarctic Survey
The North Atlantic Ocean and the Southern Ocean both feature intense convection, deep wintertime mixed layers, and steeply tilted isopycnals that connect the dynamic surface ocean with the comparatively quiescent interior. The surface-to-interior exchange pathways in both regions are important for atmosphere-ocean heat exchange and anthropogenic carbon uptake, both of which are strong controls on global and regional climate. However, the complex, temporally- and spatially-varying structure of these exchange pathways remains difficult to characterise. In this work, I use an ocean adjoint model to partially address this problem. Specifically, I (1) quantify the source waters of various convection regions (e.g. the Labrador Sea) and (2) examine the sensitivity of oceanic heat content to both local and remote oceanic properties and air-sea fluxes. By decomposing the sensitivities into “dynamic” and “kinematic” components, I distinguish advection of heat at constant density from processes/regions that can affect heat content by altering density structures and the associated transport. I will present an extensive conceptual introduction to adjoint modelling suitable for a general scientific audience, and I will highlight some possible applications of ocean adjoint modelling that are potentially suitable for future collaboration.