A MULT-APERTURE OPTICAL SYSTEM FOR IN-SITU MEASUREMENT OF THE FLUX AND SINKING SPEED OF MARINE SNOW AGGREGATES

THE OCEANS MAY REMOVE MUCH OF THE GREENHOUSE GAS CARBON DIOXIDE (CO2) THAT IS RELEASED TO THE ATMOSPHERE BY THE BURNING OF FOSSIL FUELS. DISSOLVED CO2 IS CONVERTED AT THE OCEAN'S SURFACE BY BIOLOGICAL ACTIVITY TO PARTICLES THAT CAN SINK INTO DEEP OCEAN WATER, WHERE THEY ARE EFFECTIVELY SEQUESTERED. QUANTIFYING THIS VERTICAL FLUX OF PARTICULATE CARBON IS THEREFORE ESSENTIAL FOR PREDICTING THECONSEQUENCES OF CONTINUED CO2 EMISSIONS. HOWEVER, TRADITIONAL METHODS BASED ON SEDIMENT TRAPS ARE PRONE TO ERROR BECAUSE OF HYDRODYNAMIC EFFECTS ON COLLECTOR EFFICIENCY AND COMPROMISE OF COLLECTED SAMPLES BY BIOLOGICAL ACTIVITY. THE AIM OF THIS PROJECT IS TO DEVELOP FIBER OPTIC SPARSE-PIXEL MULTI-APERTURE SENSORS (MAS) CAPABLE OF DETECTING SETTLING PARTICLES IN A REMOTE AND NONINVASIVE MANNER. MAS, BASED ON THE DESIGN OF THE INSECT EYE, ARE FAR LESS DATA INTENSIVE THAN CONVENTIONAL IMAGING SYSTEMS SUCH AS VIDEO CAMERAS. MAS, WHICH WERE ORIGINALLY CONCEIVED FOR WEAPONS SYSTEMS, ARE HIGHLY REDUNDANT AND CAN TOLERATE THE LOSS OF SENSING ELEMENTS, BIOFOULING OF OPTICAL SURFACES, AND OTHER ENVIRONMENTAL STRESSES ASSOCIATED WITH OCEAN DEPLOYMENT. THE FIBER OPTIC COMPONENTS ARE SMALL, EASILY CONFIGURED SO AS NOT DISTURB THE SENSED VOLUME OF WATER, AND INEXPENSIVE. IN PHASE I OF THIS PROJECT, A LABORATORY PROTOTYPE MAS IS BEING DEVELOPED. IN PHASE II, A COMPLETELY AUTONOMOUS SYSTEM CAPABLE OF DEPLOYMENT ON INSTRUMENTED BUOYS OR FREE FLOATING DRIFTERS IS TO BE BUILT AND TESTED AT SEA.