TY - JOUR
T1 - Shortwave Instabilities of Coastal Currents
AU - Paldor, Nathan
AU - Ghil, Michael
PY - 1991/7
Y1 - 1991/7
N2 - The finite-wavelength instability of a two-layer, inviscid coastal current is investigated numerically over a wide range of parameters, and verified analytically in a simple limiting case. We show that the instability exponents increase linearly with wavenumber and that they increase with the upper layer's mean speed. A comparison with Kelvin-Helmholtz instabilities shows both similarities and differences. For large total ocean depth, our theory predicts the existence of very vigorous instabilities whenever the slanting interface between layers extends close to the bottom on the ocean. The energy source of these instabilities is mixed barotropic-baroclinic. The theory presented here ceases to be valid at large wavenumbers, where viscous effects have to be included in the governing equations. An ad hoc extension of the inviscid theory agrees with the spatial and temporal scales of observed, finite-amplitude features in the Algerian Current, for a reasonable value of the eddy-viscosity coefficient.
AB - The finite-wavelength instability of a two-layer, inviscid coastal current is investigated numerically over a wide range of parameters, and verified analytically in a simple limiting case. We show that the instability exponents increase linearly with wavenumber and that they increase with the upper layer's mean speed. A comparison with Kelvin-Helmholtz instabilities shows both similarities and differences. For large total ocean depth, our theory predicts the existence of very vigorous instabilities whenever the slanting interface between layers extends close to the bottom on the ocean. The energy source of these instabilities is mixed barotropic-baroclinic. The theory presented here ceases to be valid at large wavenumbers, where viscous effects have to be included in the governing equations. An ad hoc extension of the inviscid theory agrees with the spatial and temporal scales of observed, finite-amplitude features in the Algerian Current, for a reasonable value of the eddy-viscosity coefficient.
KW - coastal currents
KW - frontal instabilities
KW - Kelvin-Helmholtz instability
KW - ocean
UR - http://www.scopus.com/inward/record.url?scp=84963122814&partnerID=8YFLogxK
U2 - 10.1080/03091929108227340
DO - 10.1080/03091929108227340
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
AN - SCOPUS:84963122814
SN - 0309-1929
VL - 58
SP - 225
EP - 241
JO - Geophysical and Astrophysical Fluid Dynamics
JF - Geophysical and Astrophysical Fluid Dynamics
IS - 1-4
ER -