IT has long been known that more experimental data is necessary to tune the whitecap reflectance model used to process ocean color imagery. Accurate measurements of whitecaps are difficult to…

This federal grant award to the California Maritime Academy, part of the California State University System, provides $26,035.13 to conduct research on measuring the reflectance of whitecaps in ocean color imagery. The objective is to improve the modeling of whitecap contribution to ocean color data, which is necessary for accurately processing and interpreting this imagery. The research will establish a robust dataset of hyperspectral reflectance measurements of breaking waves under varying physical conditions. This will help quantify errors in the current whitecap correction approach and develop an improved method that directly measures whitecap reflectance rather than relying on wind speed-based estimates. The findings could enhance the use of ocean color data to assess upper ocean physical processes like air-sea flux and turbulent energy exchange. There is no set-aside designation for this grant, which was awarded by the National Aeronautics and Space Administration (NASA).

IT has long been known that more experimental data is necessary to tune the whitecap reflectance model used to process ocean color imagery. Accurate measurements of whitecaps are difficult to capture therefore, no comprehensive datasets of the reflectance of naturally breaking waves under a wide range of forcing conditions exists to adequately assess the contribution of foam and bubbles to ocean color imagery. The proposed research will: 1) provide a highly accurate, statistically robust dataset of hyperspectral reflectance measurements of breaking waves during a wide range of well-characterized physical forcing conditions. These measurements can be used to identify spectral differences between whitecaps and aerosols 2) quantify uncertainty and sources of error in the current whitecap correction approach from the use of a whitecap effective reflectance estimated from a small number of individual whitecaps and breaking waves in the surf zone and the wind speed whitecap coverage relationship 3) provide an improved whitecap correction approach using an estimate of hyperspectral [PWC]n for 350-1100 NM measured directly as a function physical forcing conditions (e.g. wind speed, wind friction velocity, etc.), eliminating the use of the effective reflectance and 7 fractional coverage of whitecaps estimated using wind speed. Furthermore, because whitecaps are a part of the signal measured by ocean color sensors, ocean color data could be used to estimate upper ocean physical processes. The relationship between hyperspectral reflectance and TKE dissipation rates at the surface, bubble size distributions and void fraction, will be investigated illustrating the potential for expanding the role of ocean color into assessments of the air-sea flux and the role of wave breaking in turbulent kinetic energy exchange.