Author: Wilson  Salls,  Research Fellow (Oak Ridge Institute for Science and Education)

Description:
Chlorophyll a concentration can serve as a proxy for phytoplankton biomass, and thus as an indicator of increased anthropogenic nutrient stress. Satellite remote sensing can be a cost-effective supplement to in situ sampling. Multiple satellite platforms are capable of quantifying chlorophyll a, but results across platforms generally are not directly intercomparable due to differences in spectral resolution. The Maximum Chlorophyll Index (MCI) is one algorithm that may be transferred across satellite platforms; it can be applied to the MultiSpectral Instrument (MSI) aboard the Sentinel-2 satellites and the Ocean and Land Colour Instrument (OLCI) aboard Sentinel-3, both managed by the European Space Agency. However, these sensors collect data at slightly different wavebands, introducing the potential for an offset in MCI values. This study compares coincident MCI results from Sentinel-2 MSI and Sentinel-3 OLCI. Prior to intercomparison, the MSI data were resampled from spatial resolutions of 10 and 20 m to 300 m to match OLCI. Next, data from both sensors were processed to Bottom of Rayleigh Reflectance before calculation of MCI. Intercomparison regression results and statistical distributions for derived MCI are presented and evaluated within selected US lakes. This work seeks to enable use of both satellite platforms in tandem to increase temporal and spatial observational frequency and inform trophic status assessments across the United States.

Category: Scientific Program Abstract > Special Session > SS44 Emerging technologies for improved spatial and temporal observations of HAB and ecosystem change