THE PARTICULATE INORGANIC CARBON (PIC; AKA SUSPENDED CALCIUM CARBONATE) ALGORITHM DETECTS THE CONCENTRATION OF PIC (IN MOLES M-3) SUSPENDED IN SEAWATER. PIC IS ASSOCIATED WITH COCCOLITHOPHORES A CLASS OF PRYMNESIOPHYTE MICROALGAE THAT COVERS ITSELF WITH MICROSCOPIC SCALES CALLED COCCOLITHS. THESE CELLS AND ASSOCIATED CALCITE COCCOLITHS ARE UBIQUITOUS IN THE EARTH S OCEANS AND THEY OCCUR AT DENSITIES OF HUNDREDS ML-1 EVEN IN THE MOST OLIGOTROPHIC REGIONS (THE BIOLOGICAL DESERTS ). THEIR DENSE CALCITE COCCOLITHS SERVE AS BALLAST FOR SINKING PARTICULATE ORGANIC MATTER AND AS SUCH THEY ARE A MAJOR DRIVER OF THE OCEAN S BIOLOGICAL PUMP. THE CALCITE ALSO HAS A RELATIVE REFRACTIVE INDEX FAR GREATER THAN MOST OTHER PARTICLES IN THE SEA. THUS THE COCCOLITHS ARE HIGHLY SCATTERING TO VISIBLE LIGHT SUCH THAT THEY CAN BE EASILY SEEN FROM SPACE. THE NASA PIC PRODUCT IS A STANDARD PRODUCT FOR NASA MODIS AQUA AND TERRA AND THIS PROPOSAL IS BEING SUBMITTED TO BOTH AQUA AND TERRA BIENNIAL REVIEW TEAMS. THE ORIGINAL ALGORITHM MAINTENANCE PROPOSAL TO NASA INCLUDED THE STANDARD PIC ALGORITHM AS WELL AS A DIFFERENCING ALGORITHM WHICH AT THE TIME OF THE PROPOSAL SUBMISSION WAS IN EARLY DEVELOPMENT.