ABSTRACTS

Oral Session 7 | Wednesday, October 5, 12:20–12:40 | Abstract 567

Global Variability in Light Scattering By Different Coccolithophore Species: Impacts on Particulate Inorganic Carbon Remote Sensing

Particulate Inorganic Carbon (PIC), a dense biomineral ubiquitous in all marine systems, plays a key role in two fundamental oceanic carbon pathways: the biological carbon pump and the alkalinity pump. Both of these pathways affect the partial pressure of CO₂ in the sea in opposing ways. Because of the importance of PIC production to the ocean’s carbon cycle, there is a profound need to understand PIC concentration in space and time. Remote sensing of PIC focuses primarily on the detection of coccolithophores. Coccolithophores, and their detached calcite plates called coccoliths, are optically active, and can significantly contribute to the backscattering of light in the ocean. Prior NASA algorithms for estimating PIC (the Standard Product of Balch et. al (2005) and the Developmental Product of Mitchell et. al (2017)) make the assumption that the backscattering cross-section, or mass-specific backscattering, of PIC (bb*_PIC) is taken as the average value for a single species of coccolithophore, Emiliania huxleyi. Emiliania huxleyi is globally ubiquitous, but it is not the most abundant species at tropical and sub-tropical latitudes. We present a new bb*_PIC that varies with PIC concentration, similar to variability of the mass-specific phytoplankton absorption coefficient due to the package effect. The new bb*_PIC was derived on global field measurements, representing a wide range of coccolithophore species, thus providing a more spatially robust estimation of bb*_PIC. The new bb*_PIC reduces the error on the PIC remote sensing algorithms and is included in the latest NASA ocean color reprocessing (R2022).

Catherine Mitchell, Bigelow Laboratory for Ocean Sciences, 0000-0001-9932-3050

Sunny Pinkham, Bigelow Laboratory for Ocean Sciences

William M. Balch, Bigelow Laboratory for Ocean Sciences