Abstract Between 9 June and 6 July 2023 a SeaExplorer glider equipped with an Underwater Vision Profiler (UVP6), surveyed frontal structures between a cyclonic and two anticyclonic eddies in the Northeast Atlantic as part of the APERO cruise (Assessing marine biogenic matter Production, Export and Remineralization: from the surface to the dark Ocean) that was designed to quantify the spatial and temporal variability of the biological carbon pump (BCP) from the surface to the mesopelagic zone. Combined high‐resolution physical, biogeochemical, and imaging observations resolved particulate organic carbon (POC) distributions and fluxes across (sub)mesoscale features. Particle concentrations, POC stocks, and fluxes showed pronounced spatial heterogeneity, with sharp gradients at frontal interfaces and enhanced variability in larger particle size classes. Estimated POC fluxes varied by up to an order of magnitude over distances <10 km at the surface, with variations of up to a factor 2–3 at 1,000 m. Lagrangian backward trajectories from altimetry revealed that these signals detectable at submesoscale resulted from convergence of outer water masses in frontal zones, whereas vertical processes were primarily responsible for biogeochemical variability within eddy cores. Secondarily it is shown that optical backscattering underestimated and poorly resolved deep variability of large‐particle POC when compared with UVP‐derived ones, but it is proposed that combining both sensors may improve total POC estimates. These results demonstrate that glider‐UVP6 systems provide a powerful approach to capture fine‐scale BCP variability and constrain vertical carbon export estimates.
Chevillon et al. (Fri,) studied this question.