POSTER SESSION 2
10:30–12:30, Tuesday, September 15
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
ABSTRACT 1233 | POSTER 162
EVALUATING SATELLITE OCEAN-COLOUR ALGORITHMS ACROSS OPTICALLY DIVERSE GREENLANDIC WATERS
Greenlandic waters span a wide range of optical classes and are critical for Arctic primary productivity and carbon cycling, sustaining large fish stocks. Yet, limited field sampling restricts our understanding of biogeochemical processes in these glacially influenced environments. Satellites provide a useful tool for synoptic mapping of chlorophyll-a (Chl-a) on regional scales, yet their performance in those waters remain poorly understood. We analysed algorithms including NASA standard (OC2, OC3, OC4) and other approaches (OC4-ME, Hu CI, and ABI), applied to GlobColour merged satellite remote sensing reflectance ([image]) products, to assess their performance across spatial zones, seasons, and optical regimes. Estimates were compared to a pan-Greenland in-situ Chl-a matchup dataset collected over the past 20 years. OC2 performed best overall with R²=0.32, root mean square deviation (RMSD) of 0.39 in log-space, and median absolute percentage error (MdAPE) of 53.2%. ABI exhibited the strongest correlation (R²=0.34) but larger relative errors (RMSD=0.39, MdAPE=66.7%). OC4-ME and OC4 produced comparable results (R²=0.30, MdAPE=60.8% and 61.0%, respectively), while OC3 performed poorest (R²=0.31, MdAPE=70.6%). Algorithm performance varied considerably by region and season, with largest errors in Northwest Greenland (MdAPE>200%) and during spring blooms (MdAPE>90%), likely driven by optical complexity and lack of regional parametrizations. All algorithms systematically underestimated Chl-a at higher concentrations. These results demonstrate that globally calibrated algorithms applied to Greenland’s coastal and shelf waters produce significant uncertainties, highlighting the need for regional approaches to improve satellite-based monitoring of Arctic marine productivity.
Karthick Murugan, National Institute of Aquatic Resources, Technical University of Denmark, [email protected]
Thomas Juul-Pedersen, Greenlandic Institute of Natural Resources (GINR), [email protected]
Per Juel Hansen, University of Copenhagen, [email protected]
Rafael Gonçalves-Araujo, Technical University of Denmark, [email protected]
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
