You are here:
Using the Sentinel-2 satellite for remote sensing of chlorophyll-a in U.S. lakes
Citation:
Salls, W., B. Schaeffer, J. Werdell, B. Seegers, K. Loftin, P. Eslick, E. Urquhart, AND M. Amanatides. Using the Sentinel-2 satellite for remote sensing of chlorophyll-a in U.S. lakes. 2018 AGU Meeting, Washington, DC, December 10 - 14, 2018.
Impact/Purpose:
Presented at the 2018 American Geophysical Union Fall Meeting
Description:
Using the Sentinel-2 satellite for remote sensing of chlorophyll-a in U.S. lakes Chlorophyll-a concentration can serve as a proxy for phytoplankton biomass, an indicator of increased anthropogenic nutrient stress, and a measure of nuisance algal blooms. Here, we compare chlorophyll-a concentrations derived from satellite imagery to those obtained by in situ sampling. Satellite chlorophyll-a concentrations were derived from the European Space Agency’s (ESA) Sentinel-2 Multispectral Instrument using the Maximum Chlorophyll Index (MCI). In situ data from the Water Quality Portal, a repository for data collected by state, federal, and tribal groups across the U.S., was quality assured for validation. Initial data screening included cloud free satellite scenes, sampling depth ≤ 2 meters, sampling distance from shore ≥ 30 meters, and time difference between in situ collection and satellite overpass of up to 10 days. The spectral reflectance (before atmospheric correction) and Bottom of Rayleigh Reflection (BRR, Rayleigh removed) were evaluated as options for MCI implementation within ESA’s Sentinel Application Platform software. We present validation regression results and statistical distributions for derived MCI for nearly 1,000 lakes, reservoirs, and estuaries nationwide. The intended outcome of this work is to demonstrate use of this satellite product to assess trophic status and eutrophication level across the United States. We also investigate the sensitivity of sampling distance from shore and days between in situ collection and satellite overpass to inform future use of the algorithm. Though other studies have validated the Sentinel-2 MCI, they have done so at limited geographic regions—in most cases, individual waterbodies; this is the first such national-scale validation.
