SS1.04 Small-scale Biophysical Coupling in Plankton Ecology
Date: Thursday, June 13, 2002
Time: 2:45:00 PM
Location: Esquimalt
 
ScheurerDL, University of Maryland Center for Environmental Science, Appalachian Laboratory, Frostburg, USA, scheurer@al.umces.edu
Sanford, L, P, University of Maryland Center for Environmental Science, Horn Point Laboratory, Cambridge, USA, lsanford@hpl.umces.edu
Gardner, R, H, University of Maryland Center for Environmental Science, Appalachian Laboratory, Frostburg, USA, gardner@al.umces.edu
 
A NOVEL GRID-BASED METHOD FOR SIMULATING IDEALIZED TURBULENCE IN AQUATIC SYSTEMS
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Fickian diffusion methods are often used to parameterize turbulence mixing in spatially-explicit ecosystem models. Simulation of mixing effects at smaller scales using Fickian diffusion can be problematic due to the computational cost of fine grids and smoothing of concentration gradients from numerical diffusion errors. To avoid these limitations, we developed a computationally efficient and statistically accurate method for simulating idealized two-dimensional turbulence in aquatic systems. Based on a seeded eddy model developed for particle systems, we have adapted the technique to work within a gridded framework while still preserving the cascade of turbulent energy from broad- to fine-scales. Results from tracer decay studies show that our method reproduces the velocity spectrum of homogeneous isotropic turbulence and accurately models the spreading rate of particles from scale-dependent turbulent mixing. The advantages of this technique are that it is extremely fast and exhibits no numerical diffusion thereby allowing the simulation of realistic concentration gradients over a broad range of scales. We will also discuss potential applications of this technique for the investigation of physical-biological interactions in spatially-explicit ecosystem models.