Abstract
"My work can be divided into three main research areas. The first study focused on the Gulf Stream system as a whole. A Gulf Stream North Wall forecasting model was created using wind and buoyancy forcing. An existing model with multiple parameters including the previous year’s Gulf Stream North Wall index, location and amplitude of the Icelandic Low center, and the Southern Oscillation Index was augmented with basin-wide Ekman drift over the Azores High and validated over the last 40 years. Results indicate the possibility of better understanding and enhanced predictability of the dominant wind-driven variability of the Atlantic Meridional Overturning Circulation and of fisheries models that use the Gulf Stream path as a metric. A related work found that ring formation behavior has been asymmetric over both interannual and seasonal time-scales. Warm Core Ring formation underwent a regime shift in the year 2000 whereas Cold Core Ring formation rates remained consistent over the last forty years This increase in Warm Core Ring production leads to an excess heat transfer of 0.10 PW to the Slope Sea, amounting to7.7 to 12.4% of the total Gulf Stream heat transport, or 5.4 to 7.3% of the global oceanic heat budget at 30◦N. Seasonally, a higher (lower) number of cold rings formed in winter(summer) than warm ones. The second section of my dissertation follows a Warm Core Ring as it moves through the Slope Sea using a 10 year Ring trajectory dataset This analysis reveals a very narrow band between 66◦and 71◦W along which rings travel almost due west along ∼39◦N across isobaths - the “Ring Corridor”. The rings generated to the west of the New England Seamount Chain by a process called an aneurysm tend to have shallower vertical extent than those formed by a pinch-off mechanism from Gulf Stream to the east of the New England Seamount Chain. The last section of my dissertation focuses on the impact of a Warm Core Ring hitting the shelfbreak via an shelfbreak exchange process called the mid-depth salinity maximum intrusion. This work found the first observational evidence of a regime-shift for Salinity Maximum intrusions in the northeast US shelf waters which corresponded to a regime shift in the occupancy of Warm Core Ring along the shelfbreak. This part also links changes in the Gulf Stream with the shifts in the shelf ecosystem through exchanges of water, nutrients and plankton."