Absorption, scattering, and attenuation are inherent optical properties (IOPs) that describe how light interacts with water independent of the ambient light field. These properties have critical implications in ocean color remote sensing as they impact the light measured by satellites which is then used to produce ocean color data products such as phytoplankton community composition, chlorophyll concentration, and other biogeochemistry parameter maps. Having accurate in situ measurements of these IOPs is therefore necessary to both develop and validate data products from satellites monitoring ocean health. In situ measurements must also meet the spectral (range, resolution) requirements of these satellites; as next-generation missions, such as NASA’s Plankton, Aerosol, Cloud, and ocean Ecosystem (PACE), move from multispectral to hyperspectral measurements spanning ultraviolet to near infrared wavelengths, instrumentation for IOP measurements must similarly advance to match these capabilities. However, many sensors for in situ IOP measurements have historically been limited to single or multiple wavelengths in the visible spectrum.

Here we will present recent sensor developments for measuring hyperspectral absorption (Hyper-a), backscattering (Hyper-bb), and beam attenuation (Hyper-c) in situ in marine and freshwater environments. We will discuss the measurement principles of the sensors and key elements of the optical and mechanical designs. We will present results on calibration and characterization of the sensors to establish key performance metrics. Finally, we will present experimental results from laboratory and in situ measurements and demonstrate both the individual sensor capabilities and the complementary nature of the different measurements. We will prioritize discussion of the Hyper-c sensor, as it is the newest of the three sensors and still under development.

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