What the study found
The study found that fjords influenced by glacial meltwater and by a coccolithophore bloom can have nearly indistinguishable apparent optical properties, including remote sensing reflectance and perceived color. Although the waters look similar from above, their inherent optical properties and scattering measurements show clear differences.
Why the authors say this matters
The authors conclude that standard satellite algorithms cannot separate glacial and biogenic particle regimes in fjord systems without prior knowledge. The study suggests that autonomous observations may help quantify primary production in high-latitude coastal systems.
What the researchers tested
The researchers made comprehensive measurements of inherent and apparent optical properties in two Norwegian fjords, Gaupnefjorden and Hardangerfjorden. They compared absorption, remote sensing reflectance, RGB chromaticity coordinates, backscattering ratios, and volume scattering functions.
What worked and what didn't
In both fjords, absorption spectra had minima near 532 nm, matching the green color seen in satellite imagery. Remote sensing reflectance values and RGB chromaticity coordinates were nearly indistinguishable between the two fjords, while inherent optical properties and scattering measurements did distinguish them. Both fjords had high backscattering ratios of 0.02–0.04, and Hardangerfjorden showed more pronounced forward scattering, while Gaupnefjorden had broader angular scattering patterns.
What to keep in mind
The findings are based on two fjords in Norway and on the specific water types studied there. The abstract does not describe additional limitations beyond the statement that standard remote sensing algorithms could not separate the two particle regimes without a priori knowledge.
Key points
- Glacial meltwater and coccolithophore blooms produced nearly identical remote sensing reflectance spectra.
- Both fjords showed green or turquoise color with absorption minima near 532 nm.
- Backscattering ratios were similar in both systems, at 0.02–0.04.
- Volume scattering functions and particulate absorption distinguished the two water types.
- Standard satellite algorithms could not separate mineral and biogenic particle regimes without prior knowledge.
Disclosure
- Research title:
- Glacial and biogenic particles create similar fjord color
- Authors:
- Arne S. Kristoffersen, Elinor Tessin, Håkon Sandven, Yi‐Chun Chen, Svein Rune Erga, Børge Hamre
- Institutions:
- Bjerknes Centre for Climate Research, University of Bergen, University of Bergen, University of Bergen, University of Bergen, University of Bergen, University of Bergen
- Publication date:
- 2026-04-05
- OpenAlex record:
- View
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