Atmosphere Ocean Science Colloquium

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Stirring, Mixing, Growing: the relevance of scale awareness for plankton modeling

Speaker: Francesco Paparella, NYUAD

Location: Warren Weaver Hall 1302

Date: Wednesday, October 23, 2019, 3:30 p.m.

Synopsis:

Modeling life is the new frontier in environmental sciences. Climate modeling, fisheries management, marine conservation and antropic impact studies are examples of subjects where mathematical models must encompass both fluid dynamical and ocean biochemical processes. Much of the difficulties in this endeavor stem from the fact that those processes occur on vastly different spatial scales.

I will argue that including biochemical terms in conventional, grid-based, under-resolved ocean models inevitably generates spurious biases, and that the search for effective rates or bulk formulae of general validity should be considered as quixotic.

I will show that by giving up the conventional Eulerian modeling approach, and embracing a new Lagrangian approach where the fundamental processes of stirring, irreversible mixing and biochemical growth/decay are kept distinct, with parameters whose value remains unconstrained by the other processes, those biases may be avoided, even when the model does not resolve all the scales of motion present in the flow.

Finally, I will illustrate a practical application of the Lagrangian method by discussing the phenology of phytoplankton blooms in the open ocean, and why any believable theory of planktonic blooms should be aware of fine- and micro-scale plankton patchiness.