Understanding the circulation during the 2014 Lake Erie HABs using Lagrangian Coherent Structures

During the summer of 2014, Lake Erie was plagued by continuous harmful algal blooms (HABs) that left several major cities without clean drinking water. A previously unused tool for circulation analysis in the Great Lakes is the analysis of Lagrangian coherent structures (LCS), which represent the most attracting material lines that control mixing and transport in fluid flows. Using geometric tools, LCSs are extracted from Great Lakes Coastal Forecasting System 2D nowcast model-produced currents of Lake Erie. Then these are compared to Moderate Resolution Imaging Spectroradiometer (MODIS) images of cyanobacteria concentrations, as well as numerical drifter trajectories, to show how LCSs act as skeletons of fluid flow and how they can be used to understand pollution distribution in the Great Lakes.