TY - JOUR

T1 - Line vortices and the vacillation of Langmuir circulation

AU - Malarkey, J.

AU - Thorpe, Stephen

N1 - Natural Environment Research Council (NERC) NE/1027223/1

PY - 2016/6/23

Y1 - 2016/6/23

N2 - Three types of breakdown of Langmuir circulation (Lc) are observed, two of which are represented in largeeddysimulation (LES) models, but the third, vacillation, is not. The stability of Lc can be examined byrepresenting the downwind-aligned vortices by line vortices that are subjected to perturbations. Earlierconclusions relating to stability in homogeneous water of infinite depth are found to be in error because nostationary unperturbed state exists. The motion of vortices is examined and shown to be consistent with anexplanation of Lc devised by Csanady. Motion of line vortices in water of limited depth or bounded below by athermocline is examined. The motion replicates some of the features of vacillation observed by Smith in deepwater bounded by a thermocline, including its periodicity and fluctuations in the formation of bubble bands.Vortices describe closed orbits within the Langmuir cells. Particle motions in the vacillating Lc pattern exhibittrapping close to the line vortices or near the cell boundaries. Vacillation appears not to have been observed inwater of limited depth. Here, the vacillation period is predicted to be longer than the deep-water equivalentand may be too long for vacillations to be detected

AB - Three types of breakdown of Langmuir circulation (Lc) are observed, two of which are represented in largeeddysimulation (LES) models, but the third, vacillation, is not. The stability of Lc can be examined byrepresenting the downwind-aligned vortices by line vortices that are subjected to perturbations. Earlierconclusions relating to stability in homogeneous water of infinite depth are found to be in error because nostationary unperturbed state exists. The motion of vortices is examined and shown to be consistent with anexplanation of Lc devised by Csanady. Motion of line vortices in water of limited depth or bounded below by athermocline is examined. The motion replicates some of the features of vacillation observed by Smith in deepwater bounded by a thermocline, including its periodicity and fluctuations in the formation of bubble bands.Vortices describe closed orbits within the Langmuir cells. Particle motions in the vacillating Lc pattern exhibittrapping close to the line vortices or near the cell boundaries. Vacillation appears not to have been observed inwater of limited depth. Here, the vacillation period is predicted to be longer than the deep-water equivalentand may be too long for vacillations to be detected

U2 - 10.1175/JPO-D-16-0006.1

DO - 10.1175/JPO-D-16-0006.1

M3 - Article

VL - 46

SP - 2123

EP - 2141

JO - Journal of Physical Oceanography

JF - Journal of Physical Oceanography

SN - 0022-3670

IS - 7

ER -