14:15–14:30 | ABSTRACT 1177
MAPPING PARTICULATE INORGANIC CARBON (PIC) FROM PACE: ALGORITHM TESTING AND VALIDATION IN THE ICELANDIC BASIN AND THE NORTH SEA WITH COCCOLITHOPHORE BLOOM PHASE DETERMINATION FROM SPACE
With the launch of the PACE satellite in 2024, there is an urgent need to validate its retrievals of ocean biogeochemical variables. Particulate inorganic carbon (PIC), primarily composed of CaCO₃ produced by calcifying organisms such as coccolithophores, is a key component of the marine carbon cycle. Observed shifts in coccolithophore abundance in high-latitude oceans over recent decades underscore the need for improved satellite and in situ monitoring of PIC dynamics. To retrieve PIC from PACE, we applied a modified band-difference algorithm that will soon be implemented as NASA’s operational PACE PIC product. Cross-comparison of PACE-derived PIC with measurements from discrete water samples (R² = 0.96) and continuous underway observations (R² = 0.82) using a novel prototype optical PIC sensor in the Iceland Basin and North Sea shows promising agreement. The optical sensor dataset was independently validated against discrete PIC measurements obtained via ICP-OES (R² = 0.92). In addition to PIC retrieval, hyperspectral remote sensing reflectance from PACE reveals a distinct shift in peak reflectance from ~550 nm in early bloom stages to ~490 nm in later stages. This shift reflects an increasing coccolith-to-cell ratio and aligns with predictions from a semi-analytical hyperspectral reflectance model. The model further describes a transition in bloom color from greenish to milky-blue as blooms mature. Supporting in situ measurements, including cell counts and chlorophyll-a, are being expanded to further validate these patterns. Our results demonstrate the potential of PACE to retrieve PIC and resolve coccolithophore bloom phase, highlighting the value hyperspectral satellite observations for the ocean carbon cycle.
Timotheus Fügl*, Gent University, [email protected], https://orcid.org/0009-0003-9459-4427
Qiming Sun, Ghent University, [email protected]
Catherine Mitchell, Bigelow Laboratory for Ocean Sciences, [email protected]
Ivona Cetenic, NASA, [email protected]
Jeremy Werdell, NASA, [email protected]
Griet Neukermans, Ghent University, [email protected]
