Monitoring Coastal Surface Roughness Suppression Associated with Algal Blooms and Pollutants Using NASA SWOT Observations

Marine litter accumulation in aquatic ecosystems presents a dire problem for marine life and the human ecosystem. The presence of algae on the ocean surface can alter its response to wind-driven roughening. This alteration is the basis for a new method to detect and image algae and other roughness suppression inducing pollutants from space. The NASA Surface Water and Ocean Topography (SWOT) radar can measure coastal ocean roughness. An empirical model is developed which relates the Mean Square Slope (MSS), a measure of ocean surface roughness, to wind speed given clear water conditions. Deviations of the roughness observed by SWOT from the clear water model results in roughness anomalies that are found to be empirically associated with the concentration of chlorophyll-a observed by the NASA VIIRS instrument. The relationship between roughness anomaly and chlorophyll concentration is incorporated into a new retrieval algorithm for algae by SWOT. This retrieval algorithm has a valid range of 0–6 mg/m3.