Influence of Surface Mixing Layer on Phytoplankton

Space-born radiometers used to estimate near-surface phytoplankton community properties measure light reflected from the ocean in the visible spectrum. The depth of penetration of electromagnetic radiation in this frequency range is a function of the opacity of the ocean’s surface, ranging from a few tens of centimeters in optically-dense water to many tens of meters in clear water. The physical variability of this near-surface strata is primarily wind-driven and is nearly always entirely constrained to the so called surface mixed layer. Yet, the systematic and persistent influence of geostrophic motions, such as eddies and meanders which dominate variability below the mixed layer, can be observed in ocean color observations suggesting that the near-surface wind-driven “slab” is permeable, allowing fluxes of biologically relevant quantities to occur in conjunction with mesoscale modulations of the oceans interior. The interaction of the wind-driven oceans surface with its geostrophically-dominated interior has been a topic of much interest in the field of physical oceanography. Multiple dynamically-consistent analytical models exist that can be used to inform the interpretation of ocean color data.
We are studying the interaction of the near-surface, wind-driven “permeable slab” with the geostorophically-dominated interior ocean by analyzing near-surface ocean color observations from satellites (SeaWIFS, MODIS, and VIIRS) and air-borne sensors (GCAS and HSRL) in conjunction with in situ profiles of these optical properties and stratification in order to develop a mechanistic understanding of the interaction of the “permeable slab” with the ocean interior. Then we can begin to understand the physical and biological characteristics of this interaction to be understood.

 

This project is part of the North Atlantic Aerosol and Marine Ecosystem Study (NAAMES) supported by NASA

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