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Research» Publications» Highlights»
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Research Experiments:
Andrew Cookson, Eric Boget, and Matthew Alford, together with graduate student Kim Martini and postdoc Zhongxiang Zhao, just completed a major field experiment north of Hawaii. In two cruises totaling 50 days on R/V Roger Revelle from April through June 2006, we collected data that we hope will allow us to unravel some of the processes that befall the "internal tide," a large underwater disturbance that is generated at the Hawaiian Ridge and travels at least 1000-2000 km northward. Because it carries a substantial amount of energy, knowing where it "breaks" (in analogy with surface waves seen breaking on beaches) is important for improving models of the Earth's
climate.
Internal Waves Across the Pacific (IWAP) is a $2.6M NSF-funded collaborative
project with several Scripps researchers - Drs. Jennifer Mackinnon, Kraig
Winters (both formerly at APL-UW), Walter Munk, and Rob Pinkel. The
experiment's name is in honor of Walter's 60-year old result "Waves Across
the Pacific," where he showed that the surface waves we see on beaches have
likewise traveled all the way across ocean basins.
To measure the travel of the internal tide over these large distances, we
used a combination of techniques. The backbone of the experiment was six
moorings (picture 1, red dots) aligned with Hawaii's strongest "beam" of
tidal energy flux (arrows), which emanates from French Frigate Shoals, a
shallow ridge northwest of the beautiful Hawaiian Islands. Each mooring
consisted of a McLane moored profiler, which crawls up and down
the mooring wire between 80-1400 meters beneath the surface each hour and a
half, measuring temperature, salinity, and velocity. ADCPs, Anderaa current
meters, and Sea-bird temperature loggers were also used to capture the
shallower and deeper signals. Many of these instruments were borrowed from
other PI's, and we owe them a great debt of gratitude for their generosity.
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Read our recent publications:
Alford, M.H., M.C. Gregg and M. A. Merrifield (2006), Structure, propagation
and mixing of energetic baroclinic tides in Mamala Bay, Oahu, Hawaii, J.
Phys. Oceanogr., 36(6), 997-1018.
G. S. Carter and M. C. Gregg (2006), Persistent near-diurnal internal waves
observed above a site of M2 barotropic-to-baroclinic conversion, J. Phys.
Oceanogr., 36, 1136-1147.
Klymak, J.M., J.N. Moum, J.D. Nash, E. Kunze, J.B. Girton, G.S. Carter, C.M.
Lee, T.B. Sanford, and M.C. Gregg (2006), An estimate of tidal energy lost
to turbulence at the Hawaiian Ridge. J. Phys. Oceanogr., 36 1148-1164.
Lien, R.-C., and E. A. D'Asaro (2006), Measuring dissipation rates of
turbulence kinetic energy with a Lagrangian float, J. Ocean Atmos. Tech.,
23,7, 964-976.
Legg, S., R. W. Hallberg and J. B. Girton (2006), Comparison of entrainment
in overflows simulated by z-coordinate, isopycnal and non-hydrostatic
models, Ocean Modelling, 11, 69-97.
Reprints are available by calling 206-543-1272.
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Highlights:
Jim Carlson has returned to OPD as a Senior Engineer! His expertise is
in designing low-noise, low-frequency electronics for oceanographic
research. OPD is fortunate to have him back after his 6+ years in
private industry. He worked previously in OPD from 1980-1996.
Here's Jim Carlson working with the newly
designed Floating Electric Field Platform (FERP).
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