The objective of the project is to measure the paleoceanographic variability of heat content in the Turbulent Boundary Layer of the tropical and subtropical oceans. A new measure of the nutricline, and by proxy, thermocline, depth is the coccolithophorid species Florisphaera profunda. This marine algae is restricted to the lower euphotic zone, high nutrients, and temperatures >10C. The research will define and test this measure. The goals include (1) Improve bioecologic definition of F. profunda in the tropical Atlantic. (2) Document changes in the equatorial Atlantic nutricline for the last 200,000 years (3) Determine if the change in global climate at 2.5 Million years altered the nutricline response to precessional forcing using F.profunda in ODP site 662A for the interval 3.1 to 1.9 Million years. (4) Delineate the position and expression of the poleward boundary of the North Atlantic subtropical gyre for the last 200,000 years.
