Collaborative Research: Caribbean through-flow water mass transformation processes

The Caribbean Sea has experienced significant warming and salinification over the last couple of decades. An important component of the Atlantic Ocean circulation that transports heat northward and that is part of the Atlantic Meridional Overturning Circulation (AMOC), a key climate player, flows through it. Yet, little is known about what happens to the AMOC waters within the Caribbean Sea that then continue onward through the Gulf of Mexico and the Florida Straits to form the Gulf Stream, carrying an increasing amount of heat from the tropics to the North Atlantic. This project addresses this issue by investigating how water masses are changing in the Caribbean Sea with the specific goal of identifying processes that contribute to spatial differences in mixing via eddies and to changes in transport. Tools that will be used include observations with autonomous vehicles (gliders) across key passages and a modeling effort with the Regional Ocean Modeling System (ROMS). Results from ROMS and the glider sections will help underscore the importance of the Caribbean Sea in the changing global ocean-atmosphere system with implications for future climate and hurricane predictions. This project will address critical gaps in understanding the water mass transformation processes within the Caribbean Sea, a through-flow region for North and South Atlantic waters that form both the upper ocean limb of the Atlantic Meridional Overturning Circulation (AMOC) and subtropical Atlantic recirculation. The Caribbean through-flow represents ~25% of the northern hemisphere’s northward atmospheric-ocean heat transport. In addition, the Caribbean is highly vulnerable to tropical cyclone impacts, ecosystem degradation, and climate impacts with steadily increasing upper ocean temperatures. The hypotheses focus on the processes that modify water masses along the Caribbean through-flow system. Thus, the project includes investigation of regional differences in water mass modification processes based on (1) the spatial heterogeneity in the mesoscale eddy field; (2) the influence of steep and complex bathymetry; and (3) the influence and variability of local wind stress curl gradients. To address these differences, the project will carry out high-resolution autonomous underwater vehicle observations, investigate long-term regional model reanalysis, and conduct process-oriented model experiments of the Caribbean Sea. These efforts will improve our understanding of the mechanisms driving water mass transformation and of implications for regional and global communities. The field campaigns and modeling efforts in this project represent a crucial step towards filling significant observational and conceptual gaps in our understanding of the Caribbean Sea's role in the broader oceanic circulation system.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.