Lagrangian dispersion in sheared flow

Authored by Daniel R Lynch, Keston W Smith

Date Published: 2010

DOI: 10.1016/j.csr.2010.10.011

Sponsors: United States National Science Foundation (NSF)

Platforms: No platforms listed

Model Documentation: Other Narrative Mathematical description

Model Code URLs: Model code not found

Abstract

Two-dimensional Lagrangian trajectories are studied near an idealized ocean front with shear and convergence plus an uncorrelated random walk Applications include fixed-depth drifters and plankton patches with perfect depth regulation In the drifter case observed trajectories need to be interpreted in terms of the ensemble of possibilities In the plankton case surveys of abundance and distribution need to be interpreted similarly if vital rates are to be deduced often involving an individual-based model incorporating both biotic rates and motion In both cases forecasting requires such an ensemble description and both model skill assessment and data assimilation requires knowledge of the ensemble statistical properties Closed-form expressions are presented for mean and covariance of positions and for the important case of model-data misfit The analysis is extended to Include plankton parcels - mass and position - for parcels moving within a spatially variable growth rate originating for example in a temperature gradient The solutions support the interpretation of Lagrangian displacement data in the presence of shear evaluating Lagrangian misfit with simulation results and the use of individual-based models in spatially explicit applications (C) 2010 Elsevier Ltd All rights reserved

Tags

Diffusivity Populations Circulation Georges bank Particle-tracking Random-walk models Drift Larval cod Southern flank Coastal