Capturing Lake Mendota Seasonal Phenology with an Airborne Hyperspectral Field Campaign

New and upcoming satellite missions such as NASA’s 2024 Plankton, Aerosol, Cloud Ocean Ecosystem (PACE) and 2028 Surface Biology and Geology (SBG) missions will produce hyperspectral imagery with great potential for monitoring water quality. To better understand how hyperspectral data represent lake biogeochemical processes and states, the Lake View campaign entailed simultaneous airborne hyperspectral imaging and comprehensive in situ sampling of Lake Mendota in Madison, WI. 14 sampling events in March through November, 2024 captured the limnological conditions of Lake Mendota as it passed through seasonal phases that have distinct water optical characteristics. Such phases are driven by ecosystem functions such as food webs, nutrient cycling, and metabolism. To evaluate relationships between water quality and remote sensing reflectance, a canonical correlation analysis was performed on two groups of variables: (1) the optically active water constituents (dissolved organic carbon, total suspended solids, chlorophyll, and phycocyanin) and (2) visible wavelengths. Clusters of hyperspectral data on canonical variate axes align with known phases of Lake Mendota’s annual cycle: non-cyanobacteria phytoplankton in the spring, the clear water phase, and a cyanobacteria-dominated summer into fall. This airborne campaign helps to uncover the spectral shapes and magnitudes correlated with field measurements of coupled biogeochemical variables over time. Such information should drive us closer to monitoring dynamic lake ecosystems with hyperspectral satellites.