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Observations and numerical simulations of large‐eddy circulation in the ocean surface mixed layer
Author(s) -
Sundermeyer Miles A.,
Skyllingstad Eric,
Ledwell James R.,
Concan Brian,
Terray Eugene A.,
Birch Daniel,
Pierce Stephen D.,
Cervantes Brandy
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl061637
Subject(s) - forcing (mathematics) , mixed layer , geology , dispersion (optics) , surface layer , circulation (fluid dynamics) , large eddy simulation , mechanics , turbulence , meteorology , atmospheric sciences , materials science , layer (electronics) , physics , climatology , optics , composite material
Abstract Two near‐surface dye releases were mapped on scales of minutes to hours temporally, meters to order 1 km horizontally, and 1–20 m vertically using a scanning, depth‐resolving airborne lidar. In both cases, dye evolved into a series of rolls with their major axes approximately aligned with the wind and/or near‐surface current. In both cases, roll spacing was also of order 5–10 times the mixed layer depth, considerably larger than the 1–2 aspect ratio expected for Langmuir cells. Numerical large‐eddy simulations under similar forcing showed similar features, even without Stokes drift forcing. In one case, inertial shear driven by light winds induced large aspect ratio large‐eddy circulation. In the second, a preexisting lateral mixed layer density gradient provided the dominant forcing. In both cases, the growth of the large‐eddy structures and the strength of the resulting dispersion were highly dependent on the type of forcing.