Fig1: This scheme presents the setup of a large-ensemble simulation of 50 members performed and analyzed by Ocean Next in collaboration with IGE/MEOM, Grenoble. It has been designed to take into account the model uncertainty coming from the initial conditions and the fact that the simulated ocean has a turbulent/chaotic behavior. Instead of a deterministic description of the ocean state with time, the ensemble simulation provides a probabilistic description of the ocean state (i.e. a statistical distribution) at each time step. It allows for the detection of local non-gaussian behaviors for example (see Fig.2). For more information on this ensemble simulation, see Bessière et al, 2017.
Fig2: The probabilistic description of the ocean state allows for the detection of areas where the ocean has a strongly non-gaussian behavior, such as in the Gulf of Mexico (Figure), where a bi-modal distribution is detected in the loop-current, and an asymmetrical distribution is detected further in the Gulf, along the trajectory of the eddies released by the loop-current with an irregular frequency and then advected westward in the Gulf. The figure above shows the sea-level-height (SSH) distribution of the 50 members of the large-ensemble simulation, and compare with the AVISO satellite observation time-series. The model spread and its variations with time give an indication of the range of values (and probability) in which the satellite observations are expected to fall at each location.
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