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Intensified Diapycnal Mixing in the Midlatitude Western
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Boundary Currents
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Zhao Jing*& and Lixin Wu&
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*Department
of Oceanography, Texas A&M University, College Station, TX77840, USA
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Email: jingzhao198763@tamu.edu
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Phone :1-979-676-0762
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&Physical
Oceanography Laboratory, Ocean University of China, Qingdao, China
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Email: lxwu@ouc.edu.cn
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Phone: 86-532-82032852
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Fig S1 The horizontal wavenumber spectra of geostrophic vorticity computed from the
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sea level anomaly during the period June 2004-May 2006 (blue) and January 4-22, 2005
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(red). The region used here is 142oE-149oE, 31oN-38oN. Note that most of the enstrophy
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is contained in the horizontal wavenumber band (2  3)  10 5 rad m-1.
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Fig S2 (a) Time series of wind work; (b) Mean near-inertial kinetic energy from June
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to November 2004 (blue) and that during December 2004- January 2005. The shaded
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regions are the 90%-confidence intervals computed from the bootstrap method. The
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values are computed from the ADCP records.
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Fig S3 The mean dissipation rate in December-March (red) and in April-November
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(blue) at (a) Mooring 1, (b) Mooring 2, (c) Mooring 3, and (d) Mooring 7. Results at
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Mooring 4, 5 and 6 are discarded due to the strong vertical excursion of the moorings.
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Qi within 150-200 m under negative- and positive-  g
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Fig S4 PDFs of vertical mean
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conditions. The PDFs are computed using the ADCP data at all the moorings over the
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entire period (Jun 2004- May 2006). As 150-200 m is below the mixed layer, vertical
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mean
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downward near-inertial energy flux. It should be noted that the near-inertial wind work
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plays a dominant role in the near-inertial energy budget. As the wind work is only
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available at Mooring 7 during Jun 2004-Oct 2005, we are not able to isolate the effect
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of relative vorticity from wind work at the other sites and the other periods. However,
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we expect that the aliasing due to wind work should be significantly reduced by
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averaging over all the sites and periods as the near-inertial wind work is generally
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independent from the relative vorticity.
Qi within 150-200 m can be treated as a rough measurement for the strength of
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Fig S5 Vertical wavenumber spectra for (a) strain and (b) buoyancy-frequency-
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normalized shear. The spectra are binned with respect to the GM-normalized strain and
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shear variance with the legend representing the ratio of the number of profiles with
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GM-normalized strain and shear variance within a certain range to the number of total
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profiles. The grey dashed line represents GM model spectrum with the dotted line
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representing the saturated model spectrum. The black solid line in (b) denotes the
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spectrum for shear noise computed by quadratic fitting (  0 k 2 ) the observed shear
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spectra at high-wavenumber end.
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Table S1 Correlation coefficient of dissipation rate to near-inertial shear variance S i ,
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super-inertial shear variance S s , and background stratification N 2 .
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S i2
S s2
N2
300-600 m
0.51
0.10
0.13
450-750 m
0.48
0.09
-0.17
600-900 m
0.52
0.14
0.29
750-1050 m
0.59
0.17
0.18
900-1200 m
0.58
0.14
0.19
1050-1350 m
0.40
0.11
-0.09
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