Abstract:

The Atlantic Meridional Overturning Circulation (AMOC) is an essential component of the climate system due to its vital role in the global distribution of heat, carbon, and water masses. The downwelling of North Atlantic surface waters connecting the upper and lower AMOC limbs is an essential yet vulnerable part of this global circulation, which partly occurs along continental boundaries. This study presents an extended observational investigation on the quantification of Eulerian-mean downwelling along the continental slopes of the North Atlantic subpolar gyre (SPG) and an examination of the underlying mechanisms, with an emphasis on the role of mesoscale eddies.

A volume budget of the SPG boundary reveals a total Eulerian-mean (2002-2019) downwelling of -4.41±0.96 Sv at 1300 m depth between Denmark Strait and Flemish Cap, with the barotropic transport (BT) contributing 2.66±0.40 Sv and the baroclinic transport (BC) contributing 1.75±0.43 Sv. To investigate the processes that cause the BC boundary downwelling, i.e., the boundary heat loss and associate along-boundary density gradient, the long-term mean heat budget of the boundary current system is studied. Both lateral heat fluxes, driven by the boundary current/mesoscale eddies, and air-sea heat flux play significant roles in the boundary heat loss. In a Lagrangian framework, it is found that cross-shore eddy propagation generally cools the SPG boundary.

Biography:

Yingjie Liu is a physical oceanographer who seeks to understand the physical dynamics of subpolar North Atlantic ocean circulation. She received her PhD degree in December, 2022 from the French Research Institute for Exploitation of the Sea (IFREMER) under the supervision of Dr. Damien Desbruyères and Dr. Herlé Mercier. Her PhD thesis focuses on observational study of the vertical dynamics of subpolar gyre overturning. She is currently a postdoctoral researcher in the Department of Atmospheric and Oceanic Sciences at Fudan University, working with Prof. Guihua Wang. Yingjie Liu received a BSc degree from Nanjing University of Information Science and Technology (NUIST) and an MSc degree from Grenoble Alpes University, France. Her research interests include ocean’s role in climate, North Atlantic dynamic, and turbulent mesoscale dynamics.

Tencent (腾讯会议) Link: https://meeting.tencent.com/dm/766emCFpzDuO

Conference ID (For Tencent): 854-430-173