Example of multisatellite validation of altimetry-based Lagrangian diagnostics. Panels (A) and (B) show the blooming chlorophyll plume during spring 2011. Panel (C) shows the reconstruction of the plume on the basis of altimetry alone (global product). Panel (D) uses the same Lagrangian model of panel (C) , but on the optimized AVISO regional product. The black circle shows a chlorophyll lobe which only the regional product is capable to reproduce. This type of validation will be integrated by the large number of Lagrangian drifters released in the region during the KEOPS2 campaign.
The understanding of the physical mechanisms that control the distribution of marine species in the open ocean is a challenging and interdisciplinary issue. The limited knowledge of such mechanisms currently hinders our ability to manage marine resources, protect biodiversity, and estimate the impact of natural and anthropogenic environmental changes over the oceanic biota. Altimetry cannot detect directly biological information. However, when opportunely analyzed, altimetry provides uninterrupted, mesoscale-resolving observations of transport and mixing, which are currently emerging as key drivers in structuring biodiversity and trophic interactions in the open ocean. This project describes ongoing efforts to explore the role of mesoscale turbulence on the dynamics of marine ecosystems. We ask support for some specific actions, which will showcase to the marine biology community the yet untapped potential of altimetry for ecological applications. The project is oganized along three axes. The first axis concerns the theoretical development of novel transport diagnostics. It focuses on the altimetry-related properties that have recently appeared as the most ecologically relevant, and notably aggregation/dispersion mechanisms and front dynamics. A second axis is an in- depth validation study focused on the Kerguelen region, where an optimized regional altimetry product, Lagrangian drifters trajectories, three-dimensional in situ observations, and model data are combined together. The third axis applies these diagnostics, comparing them to state-of-the-art global maps of biodiversity and to maps of fish distribution and of foraging habitats for marine predators. Some deliverables of this project are a technique for forecasting the dynamics of fronts from near-real-time altimetry and a mesoscale-resolving validation of altimetry-derived transport structures based on a large number (50) of drifters deployed during the KEOPS2 campaign.