- Measurements with Sequoia Scientific’s Hyper-a and Sea-Bird Scientific’s ac-s collected in East Sound, WA on May 20, 2024, during a period of strong Noctiluca scintillans bioluminescence
- The comparison is not strictly one-to-one, as the two instruments sampled slightly different water volumes.
- The ac-s remain the only mature, routinely available commercial in situ hyperspectral absorption meter.
- Sequoia’s Hyper-a has been commercially available since 2024. It provides much higher spectral resolution. It also reveals narrow spectral features missed by the ac-s, and extends into the UV (300 nm – 710 nm).
Comparison of hyperspectral absorption measurements (apg , left y-axis) and their second derivatives (right y-axis) collected on May 20, 2024 in East Sound, Orcas Island, WA, USA. Data from two instruments: Hyper-a (red line) and ac-s (blue line with markers). Prominent absorption features appear at 379, 411, 439, 462, 493, 589, 618, 637, and 671 nm, corresponding to known pigment signatures in Chaetoceros socialis and Pyrocystis fusiformis populations present during the Noctiluca scintillans bloom. The plot overlays second-derivative spectra to highlight band minima.
Both instruments capture the main absorption envelope, confirming consistent total pigment absorption and show overall shape agreement. Hyper-a has a spectral resolution advantage: Its dual-spectrometer, hyperspectral system (~2 nm resolution) detects narrow pigment features that the ac-s (with ~4–10 nm spacing) does not resolve.
- The 440–460 nm maximum is diagnostic of peridinin-containing dinoflagellates, confirming Noctiluca’s carotenoid signature. The broad peridinin band (440–470 nm) appears smoother and slightly stronger in Hyper-a. The ac-s underestimate the peak amplitude.
- Hyper-a resolves finer structure: Around 500–550 nm, Hyper-a shows subtle curvature and a defined minimum. The ac-s produces a flatter, featureless response.
- The valley around 550 nm represents the green window where peridinin and chlorophyll absorb weakly. This gives Noctiluca its orange-brown appearance.
- The 675 nm chlorophyll-a peak confirms the presence of photosynthetic pigments (though Noctiluca is mixotrophic, not a strong chlorophyll producer).
Hyper-a full view
Data, figures, and descriptions courtesy of Alberto Tonizzo, Chris Strait, Mike Twardowski, Sunstone Scientific LLC, and Florida Atlantic University – HBOI, USA. The Hyper-a was developed with NASA SBIR funds on contracts #80NSSC20C0472 and 80NSSC21C0491 to Sequoia Scientific, Inc. with Sunstone Scientific, LLC as subcontractor.