Measurement of hyperspectral underwater light fields

There is a current trend in optical oceanography to move from multispectral observations (involving a small number of wavebands of around 10. nm bandwidth) to hyperspectral observations (with contiguous spectral sampling at around 3-5. nm intervals). Hyperspectral imaging systems for subsea and aerial deployment are widely available, and advanced plans are in place for new satellite-borne sensors. The advantages of hyperspectral measurements include improved capabilities for water mass and benthic feature discrimination, and the ability to resolve inelastic processes, such as Raman scattering and chlorophyll fluorescence. This chapter reviews techniques for measuring underwater light fields at the resolution required to support hyperspectral imaging, and considers the main factors that must be taken into account in instrument design, calibration and deployment. It also identifies areas where further technical development is required, including shorter spectral acquisition times and improved deployment techniques in shelf seas and coastal waters.