We have performed a series of numerical simulations designed to investigate
the lateral dispersion of a tracer in a field of submesoscale oceanic
vortices.
Motivation for our numerical study comes from a series of dye-tracer releases
conducted as part of the Coastal Mixing and Optics experiment
(henceforth CMO) during late summer stratification over the New
England shelf. Observed dye patterns revealed, among other things,
significant lateral mixing at small
scales traditionally ascribed to internal waves which cannot
be reconciled with traditional models of lateral dispersion, namely,
shear dispersion and dispersion by lateral intrusions (Sundermeyer, 1998;
Sundermeyer and Ledwell, 2001; Sundermeyer et al., submitted).
A similar result was also found during the North Atlantic Tracer Release
Experiment (NATRE) in the pycnocline of the open ocean (Ledwell et al. 1993,
1998; Sundermeyer and Price, 1998). Specifically, in that case, observed
dispersion on scales of 1-10 km was 40 times that predicted by internal
wave shear dispersion. Temperature and velocity
microstructure measurements taken during CMO (Oakey and Greenan, submitted;
Sundermeyer et al., submitted) showed the presence of patchy
regions of intense mixing superimposed on a relatively quiescent background
of low diapycnal diffusivities. It is
speculated that these well mixed regions of
represent the end-state of random, localized
wave-breaking or shear instability events. These turbulent regions exhibited
patchiness on the
same spatial scales as the dye, leading to the conjecture that the small-scale
dye dispersion observed during CMO may be attributed to the presence of
submesoscale vortical motions which are formed by the adjustment
Principal results:
List of publications resulting from this project:
Details pertaining to this study can be found in two companion publications.
Both articles are available below.
Click here to download a copy of Lelong and Sundermeyer (J. Phys. Oceanogr., 35,(12), 2352-2367, 2005.)
(ps), (pdf).
Click here to download a copy of Sundermeyer and Lelong (J. Phys. Oceanogr., 35,(12), 2368-2386, 2005.)
(pdf).
(If you're unable to download the pdf files, try holding the Shift key
while downloading)
Further details pertaining to this project and to the dye-release field
experiments can be found on:
Miles Sundermeyer's Webpage
.