13 July 1999
The figures to follow show how the near-bottom results were obtained. First is an example tow track, followed by estimates of ``chi'' from another of our tows. From ``chi'' and the temperature gradient one can estimate eddy diffusivity (K) and heat flux using the Osborn-Cox model for diapycnal heat diffusion.
Depth record of tow Deep-8.
``Chi'' (linear and log) and the depth-track for tow Deep-5.
The next two figures show results from tow Deep-6, performed near the BASS bottom tripod near the CMO central site.
The statistics of thermal dissipation rate ``chi'' from
tow Deep-6 show a wide dynamic range (histogram, lower frame) and a nearly
log-normal probability distribution (upper frame). The variable examined
here is the greater of two ``chi'' estimates resulting from the ``white
spectrum'' correction method (Washburn et al, JAOT 1996). The two estimates
have different assumptions about T/S coherence, which is uncertain in the
thermal diffusive rolloff region.
Below, the uncorrected (left) and corrected upper-bound
(blue) and lower-bound (red) estimates of ``chi'' (right) from the
microconductivity probe are shown. The corrections depend on the local
TS relation. Mean profiles of salinity (green) and temperature (red)
are on the left. The results are averaged for all 10 tows in layers
(defined by temperatures) to get the mean profiles shown above.
Summary plot of deep-towing results (in blue), with bootstrap
intervals (95%) and the dye result (magenta, near N=20).