Illustration: A Lagrangian view on the evolution of a plankton patch
Schematics showing the evolution in space and time of a planktonic system embedded within a fine-scale water patch stirred by the ocean currents. The patch is enriched by a local injection of nutrients, making it biologically richer than the waters surrounding it. As time passes, the accumulated biomass transfers across trophic levels, from primary producers to top predators, with part of it sinking to the deep waters. Changes in water properties affect fluxes of gases and particles across the air-sea interface. Because of horizontal
stirring, the patch is advected and stretched until it forms a filament whose boundary is delineated by Lagrangian coherent structures (LCSs). The stretching process is expressed by the spread of Lagrangian floats initiated at adjacent locations. Taking a Lagrangian viewpoint allows one to characterize the structuring effect of the oceanic currents and quantify internal changes within the planktonic system as it is advected and deformed. Taken from Lehahn et al., ARMS, 2018.