Chlorophyll Distributions in Relation to Physical Processes off Long Bay, South Carolina, USA, in the Winter of 2012

In the winter of 2012, a field program was conducted off of Long Bay, South Carolina, USA. Previous studies have observed anomalously high wintertime productivity in this region of the South Atlantic Bight. Over a ten week period, two gliders measured temperature, salinity, chlorophyll, scatter, CDOM, and dissolved oxygen from the mid-shelf to the upper slope. These variables were also measured using ship transects. Three moorings deployed on the shelf and slope provided ADCP, CTD, and bio-optical time series. Strong spiking of the chlorophyll signal was observed during blooms containing colony-forming phytoplankton. Using a statistical measure, we classify the chlorophyll data as either a “spike” (colony) or part of the “background” (small forms). Using the glider data, we then show how each set evolves in space and time, correlating the changes to observed physical processes. Despite anomalously warm conditions , high chlorophyll concentrations were observed during three events--in late January/early February, in mid-March, and in late March. Circulation associated with warm equatorward-flowing jets over the upper slope may have been responsible for structuring these events.