Hyperspectral radiometric device for accurate measurements of water leaving radiance from autonomous platforms for satellite vicarious calibrations

Maintaining sufficient accuracy over the lifetime of satellite-based ocean-viewing radiometry missions requires a robust vicarious calibration program to enable routine verification of the ocean color instrument calibration while on orbit. In addition to a small number of highly instrumented sites, a spatially extensive network of vicarious calibration match-up data points helps to achieve the desired level of calibration uncertainty. The next generation of ocean color satellite sensors such as the Pre-Aerosol Clouds and ocean Ecosystem (PACE) mission builds on past ocean color remote sensing efforts to provide a global observational basis for understanding the living ocean and for improving skill in forecasting and projecting variability of the Earth System over a wide range of time and space scales. These are being enabled by significant advances in ocean color satellites including enhanced spatial resolution and a wider spectral range extending into the UV and near-infrared (350 - >900 nm) with hyperspectral resolution (5 nm). These enhancements drive the need to augment vicarious calibration capabilities, notably in regard to the extended spectral range into the UV, and especially with regard to the increased spectral resolution. Here we propose to build on a strong heritage to achieve an evolutionary development of a new hyperspectral radiometer system capable of meeting new requirements for spectral resolution (<3 nm), for observations in the UV and near IR (350-900 nm) and which will maintain the demonstrated accuracy, precision and stability of existing radiometers. Working with NIST, the radiometers will be fully calibrated and characterized following existing protocols. The instruments will be integrated onto autonomous profiling floats for untended optical profiling over periods of 3+ years in the open ocean. Lastly, field evaluations and validations are planned near the two fixed calibration sites near Hawaii and in the Mediterranean Sea. The benefit will be a new vicarious calibration capability for PACE and other ocean color remote sensing instruments.