Terray Eugene A.

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Terray
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Eugene A.
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Author: Ledwell, James R. × End date: 2014 ×

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  • Article
    Three-dimensional mapping of fluorescent dye using a scanning, depth-resolving airborne lidar
    (American Meteorological Society, 2007-06) Sundermeyer, Miles A. ; Terray, Eugene A. ; Ledwell, James R. ; Cunningham, A. G. ; LaRocque, P. E. ; Banic, J. ; Lillycrop, W. J.
    Results are presented from a pilot study using a fluorescent dye tracer imaged by airborne lidar in the ocean surface layer on spatial scales of meters to kilometers and temporal scales of minutes to hours. The lidar used here employs a scanning, frequency-doubled Nd:YAG laser to emit an infrared (1064 nm) and green (532 nm) pulse 6 ns in duration at a rate of 1 kHz. The received signal is split to infrared, green, and fluorescent (nominally 580–600 nm) channels, the latter two of which are used to compute absolute dye concentration as a function of depth and horizontal position. Comparison of dye concentrations inferred from the lidar with in situ fluorometry measurements made by ship shows good agreement both qualitatively and quantitatively for absolute dye concentrations ranging from 1 to >10 ppb. Uncertainties associated with horizontal variations in the natural seawater attenuation are approximately 1 ppb. The results demonstrate the ability of airborne lidar to capture high-resolution three-dimensional “snapshots” of the distribution of the tracer as it evolves over very short time and space scales. Such measurements offer a powerful observational tool for studies of transport and mixing on these scales.
  • Article
    Observations and numerical simulations of large-eddy circulation in the ocean surface mixed layer
    (John Wiley & Sons, 2014-11-06) Sundermeyer, Miles A. ; Skyllingstad, Eric D. ; Ledwell, James R. ; Concannon, Brian ; Terray, Eugene A. ; Birch, Daniel ; Pierce, Stephen D. ; Cervantes, Brandy T. Kuebel
    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.