Uncertainty assessment for a novel optically shallow water radiometric acquisition platform

Abstract We present a novel motorized platform, a custom‐built jet‐ski designed for acoustic and radiometric measurements in optically shallow coastal waters. This platform integrates in‐water radiometers with single‐beam and multi‐beam acoustic sensors, along with a suite of active and passive instruments (conductivity‐temperature‐depth, fluorescence, and backscattering sensors). Such a configuration is particularly well‐suited for environments where water depth, bottom type, and optical properties must be jointly characterized. Here, we perform a detailed assessment of the platform's design and its impact on the uncertainty of radiometric measurements and derived apparent optical properties (AOPs). Using a Monte Carlo approach, we propagated uncertainties associated with radiometric measurements, sensor depth, platform tilt, and self‐shading corrections. The total uncertainty budget was decomposed to identify the relative contribution of each component. Our results show that over half of the total uncertainty originates from upwelling radiance measurements at two depths near the sea–air interface. The shallower sensor ( 15 cm) contributes 37–48% of the uncertainty, while the deeper sensor ( 30 cm) accounts for 19–27%. Downwelling irradiance above the surface contributes an additional 12–20%. Overall, the uncertainty associated with in‐water radiometry from the jet‐ski was comparable to that of above‐water systems (e.g., HyperSAS) operated simultaneously at two stations. These findings support the use of the jet‐ski platform for research applications in optically shallow waters, offering a reliable and mobile solution for spatially extensive sampling and remote sensing validation.