This study will examine the dynamics of the interaction of a shelfbreak jet with a western boundary current and associated offshore transport of shelf water masses. This situation occurs in the north Pacific (Kuroshio/Oyashio), south Atlantic (Brazil/Malvinas currents), and Cape Hatteras (Gulf Stream,/shelfbreak front). The focus will be on the region north of Cape Hatteras, where the shelfbreak front detaches from the continental shelf and becomes entrained in the Gulf Stream. The science questions to be addressed are: --The response of the shelfbreak jet (acceleration/deceleration and separation from the continental shelf) to motion of the Gulf Stream front relative to the shelfbreak, -- Response of the shelfbreak front to forcing by strong wind stress and surface heat loss -- Dynamics by which outer shelf water is entrained into the Gulf Stream -- How the shelf dynamics are affected by the narrowing shelf width approaching Cape Hatteras, with focus on the vorticity dynamics.
A combination of existing high-resolution data sets including those collected during the Frontal Interactions Near Cape Hatteras (FINCH) program as well as a sub-regional numerical model to investigate these questions will be utilized. The numerical model will be a ?child? sub-domain of a larger scale model of the entire Middle Atlantic Bight. Supporting data including sea surface temperature and satellite-based altimetry will also be used to gain insight into frontal motions and their response to forcing.
Intellectual Merit This work will be of importance to understanding fundamental dynamics of shelf water export in a known region of mean offshore transport. The sub-regional model will be important in understanding long-term trends in fresh water transport and shelf-slope exchange in this area. This region is similar to other important regions of large shelf export including the Kuroshio/Oyashio convergence in the north Pacific and the Malvinas/Brazil current convergence in the South Atlantic. This is also a region where organic carbon transport from the shelf to the deep ocean is important.
Broader Impacts The Hatteras region contains numerous commercial fisheries as well as endangered marine mammal species. Results will be communicated to appropriate fisheries scientists and cetologists. The modeling effort will include graduate student support. Gawarkiewicz will continue activities at the Children's School of Science at Woods Hole, where he has been on the Board of Directors for five years, and has initiated the purchase of oceanographic instruments (including a video-equipped ROV), spoken extensively in classes, assisted in recruitment and evaluation of teachers, and helped develop course activities for a number of classes.
