Potential vorticity dynamics of the meridional overturning circulation

The meridional overturning circulation (MOC) is an important component of the general ocean circulation and the global climate system. The MOC is forced at high latitudes yet must navigate 1000s of kilometers of latitude to connect the source and sink regions. The dynamics that control the pathways, residence times, and meridional coherence of the MOC are not well understood. The primary intellectual merit of the proposed work is the development of a theoretical basis to better understand how water parcels of the MOC transit from low to high latitudes. In this study the potential and relative vorticity budgets will be evaluated along the MOC pathways to identify the leading order physics and key regions of potential vorticity modification that occur as parcels transit from low to high latitudes. The relative vorticity analysis will reveal the regions and mechanisms that control the vertical transport, which is the MOC in depth space and is also important for the large-scale dynamics and exchanges between the interior and mixed layer. The approach will make use of a high resolution, idealized configuration of the mid-latitude wind- and buoyancy-forced circulation and the most recent ECCO state estimate. The idealized approach, for both the theoretical and numerical components, complements the global climate models more commonly used to study the MOC. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.