【Institution】: Duke University, USA

【Host】: Xiao-Hai Yan   【Contact】: Shihui Li

Bio:

I am a physical oceanographer at the Nicholas School of the Environment, Duke University. My research has centered on physical processes in the North Atlantic. In particular, I am interested in the mechanisms that derive the variability that we observe

in the gyre and overturning circulation in the region. The areas of research I am working on include seasonal-to-interannual changes in the meridional overturning circulation and the associated heat and freshwater transport in the subpolar region, the relationship between deep-water formation at high latitudes and large-scale Atlantic circulation (gyre and overturning), and the strength of the link between the overturning circulation at subpolar and subtropical latitudes. Main research projects I am currently working on are focused on the Overturning in the Subpolar North Atlantic Program (OSNAP). OSNAP is an international joint effort of eight nations, which deployed 53 moorings in 2014 stretching from Labrador to Greenland to Scotland. OSNAP is aiming to providing a multi-year record of full-water column, trans-basin transports of volume, heat, and freshwater in the subpolar North Atlantic. I am a member of the OSNAP Observation Team and Data Products Working Group.

Abstract:

The Atlantic meridional overturning circulation(AMOC)is a key component of the global climate system through its transport of heat and freshwater.  The AMOC is characterized by a northwards flow of warm salty water in the upper layers of the ocean balanced by are turn flow of cold, fresh water in intermediate and deep layers. Modeling studies have suggested that climate change would weaken AMOC by impeding the formation of dense waters at high latitudes of the North Atlantic.  But so far, there has been no conclusive observational evidence for such alinkage between deep-water formation and AMOC variability. In addition, observations have indicated the AMOC to be far more cpricious than the models have been able to capture.  Given the imperative of mechanistic understanding of AMOC variability, a new international observational program, OSNAP (Overturning in the Subpolar North Atlantic Program), has been developed for sustained trans-basin measurements at subpolar latitudes. Deployed in the summer of 2014, OSNAP is continuously recording the full-depth volume transport associated with the AMOC as well as heat and freshwater transports. Together with existing observational efforts in other parts of the Atlantic, OSNAP will offer anunprecedented chance of understanding the mechanisms that underpin AMOC variability across the Atlantic Basin and how climate change in the subpolar region could affect it. In this talk, I present first results from OSNAP on the AMOC and deep-water formation in the subpolar North Atlantic.