Using Autonomous Vehicles to Estimate Vertical Fluxes and Remineralization Rates of Particulate Organic Matter in the Ocean: A Conceptual Approach

Autonomous vehicles are able to sample continuously and over different spatial and temporal scales. They routinely determine biological properties, such as phytoplankton fluorescence and optical backscatter. Using appropriate calibration samples taken in close proximity to the vehicles, these properties can be converted to absolute quantities of chlorophyll and particulate organic carbon (POC), respectively. By sampling through time in a relatively uniform and restricted area, the vertical distributions of particulate organic carbon can be determined, and when coupled to an estimate of surface phytoplankton production, an estimate of the vertical flux of carbon can be made from the changes in POC through time. These flux estimates in turn can be used to determine the extent of remineralization within the water column. Such remineralization rates are difficult to determine using alternative sampling techniques, and using autonomous vehicles in this manner can greatly improve our understanding of the rates of vertical flux of organic matter from the upper layers of the ocean to the deep sea, as well as the time varying rates of remineralization. These data can then provide critical inputs into global carbon cycle estimates and the role of the ocean in sequestering carbon.