Martin Losch

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Fertilization of the ocean by adding iron compounds has induced diatom-dominated phytoplankton blooms accompanied by considerable carbon dioxide drawdown in the ocean surface layer. However, because the fate of bloom biomass could not be adequately resolved in these experiments, the timescales of carbon sequestration from the atmosphere are uncertain. Here(More)
The possibility of using topography in a state estimation context as a control parameter is explored in a linear barotropic shallow water model. Along with its adjoint, the model is used to systematically assess the influence of the depth field on the modeled circulation in a steady state. Sensitivity of the flow field to the topography is greater in a(More)
A data assimilation technique is used with a simple but widely used marine ecosystem model to optimize poorly known model parameters. A thorough analysis of the a posteriori errors to be expected for the estimated parameters was carried out. The errors have been estimated by calculating the Hessian matrices for different problem formulations based on(More)
Geological evidence suggests that marine ice extended to the Equator at least twice during the Neoproterozoic era (about 750 to 635 million years ago), inspiring the Snowball Earth hypothesis that the Earth was globally ice-covered. In a possible Snowball Earth climate, ocean circulation and mixing processes would have set the melting and freezing rates(More)
[1] Stratospheric ozone depletion and emission of greenhouse gases lead to a trend of the southern annular mode (SAM) toward its high-index polarity. The positive phase of the SAM is characterized by stronger than usual westerly winds that induce changes in the physical carbon transport. Changes in the natural carbon budget of the upper 100 m of the(More)
7 Experiments with idealized geometry are used to compare model solutions of implicit VP-and explicit EVP-solvers in two very different ice-ocean codes: the regular-grid, finite-volume Massachusetts Institute of Technology general circulation model (MITgcm) and the Alfred Wegener Institute Finite Element Ocean Model (FEOM). It is demonstrated that for both(More)
Between ;750 and 635 million years ago, during the Neoproterozoic era, the earth experienced at least two significant, possibly global, glaciations, termed ''Snowball Earth.'' While many studies have focused on the dynamics and the role of the atmosphere and ice flow over the ocean in these events, only a few have investigated the related associated ocean(More)
11 Current sea ice models use numerical schemes based on a splitting in time 12 between the momentum and continuity equations. Because the ice strength 13 is explicit when solving the momentum equation, this can create unrealis-14 tic ice stress gradients when using a large time step. As a consequence, 15 noise develops in the numerical solution and these(More)