Observations of phytoplankton response to submesoscale forcing in Southern California Bight

Modeling studies have shown the potential influence of submesoscale forcing on phytoplankton dynamics. However, due to their small time and space scales of development, observations of these responses have been difficult to obtain. These observations are needed both to confirm model results and to quantify the evolution of the phytoplankton response over time. We quantified these changes in phytoplankton biomass associated with submesoscale eddies using airborne observations of ocean color (VNIR-HSI) and thermal (IR) collected during experiments in Southern California Bight, near Santa Catalina Island. We will show numerous examples of clear ocean color response to these features. While this sampling approach provides high spatial, spectral, and temporal resolution (through repeated overpasses) of the ocean surface, they only provide limited information about vertical changes in the water column. Bio-optical modeling and a unique in situ sampling strategy, including a towed instrument array provide details about subsurface dynamics. We also contrasts features observable in airborne IR imagery with different wavelengths of the hyperspectral ocean color data to provide information on the depth details of various physical forcings. These data provide evidence suggesting that the observed increase in phytoplankton biomass in the eddy core is related to a lifting of a subsurface chlorophyll maximum into the first optical depth observable to the remote sensor rather than growth of phytoplankton.