ABSTRACT 1245 | POSTER 4
FROM IN SITU TO SATELLITE: EVALUATING THE TRANSFERABILITY OF BIO-OPTICAL RELATIONSHIPS FOR IOP RETRIEVAL IN TROPICAL COASTAL WATERS
Retrieval of inherent optical properties (IOPs) from satellite data remains a challenge in optically complex coastal waters. This study evaluates the transferability of bio-optical relationships for estimating IOPs using five reflectance representations: in situ hyperspectral Rrs, in situ Rrs resampled to PRISMA and Sentinel-2 (S2) band configurations, and Rrs extracted direclty from PRISMA and S2 satellite imagery. Rrs and phytoplankton absorption, non-algal particle absorption, colored dissolved organic matter absorption (aCDOM), and chlorophyll-a (Chl-a), were collected in the Costa dos Corais Environmental Protection Area, Alagoas, Brazil, in December 2022. For each Rrs source, an independent full-spectral search identified the optimal single-band and band-ratio predictors for each IOP, allowing each source to achieve its best possible retrieval performance. Band-ratio models consistently outperformed single-band approaches, with aCDOM improving from R²=0.481 (single band at 727 nm) to R²=0.965 using Rrs(625)/Rrs(585). Results reveal a two-stage degradation in IOP retrieval performance: spectral resampling of in situ Rrs leads to moderate accuracy loss, whereas extracting Rrs from satellite imagery causes a sharp accuracy decline. aCDOM degraded from R²=0.965 to 0.102 and 0.066, and Chl-a from R²=0.884 to 0.747 and 0.062, for in situ, PRISMA and S2 imagery, respectively. Cross-validation confirmed robust in situ relationships for aCDOM (R²_cv = 0.929) and Chl-a (R²_cv = 0.807). These findings suggest that the primary limitation in IOP retrieval is likely not spectral resolution, but effects introduced during operational satellite retrieval, potentially including atmospheric correction, sensor noise, and within-pixel heterogeneity, warranting systematic investigation to guide future validation efforts for ocean color missions.
Thais Andrade Galvao de Medeiros, National Institute For Space Research (INPE), Brazil, [email protected], https://orcid.org/0000-0002-5583-4788
Julia Caon Araujo, Federal University of Rio de Janeiro, [email protected], https://orcid.org/0000-0003-3492-3658
José Carlos Sícoli Seoane, Federal University of Rio de Janeiro, [email protected], https://orcid.org/0000-0001-7728-3764
Milton Kampel, National Institute For Space Research (INPE), [email protected], https://orcid.org/0000-0002-0011-2083
Vittorio Brando, Consiglio Nazionale delle Ricerche, [email protected], https://orcid.org/0000-0002-2193-5695
Maria Laura Zoffoli, Consiglio Nazionale delle Ricerche, [email protected], https://orcid.org/0000-0003-1892-0051
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