Here is a plot of the upper 400 meters of the latest seaglider section off of Iquique (27 March - 07 April 2009, onshore to offshore track). On a hunch I plotted salinity contour lines on top of the oxygen (upper right) and backscattering (middle right) data. It seems that there is tight coupling between salinity and both O2 and bb. Before seeing these data, I would have guessed that variability in the deep oxycline would be driven by intrusions of water masses with different density and oxygen characteristics. Likewise with the bottom boundary of the intermediate depth scattering maximum. However, given what we see here, the story seems to be a bit more interesting than that! Why would salinity be more influential than density in regulating these distributions?
Monday, April 13, 2009
MOOMZ SG157 - Line 5
Here is a plot of the upper 400 meters of the latest seaglider section off of Iquique (27 March - 07 April 2009, onshore to offshore track). On a hunch I plotted salinity contour lines on top of the oxygen (upper right) and backscattering (middle right) data. It seems that there is tight coupling between salinity and both O2 and bb. Before seeing these data, I would have guessed that variability in the deep oxycline would be driven by intrusions of water masses with different density and oxygen characteristics. Likewise with the bottom boundary of the intermediate depth scattering maximum. However, given what we see here, the story seems to be a bit more interesting than that! Why would salinity be more influential than density in regulating these distributions?
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Amanda,
ReplyDeleteRe: density vs. salinity
Remember density is a dynamically active property; it needs to be stably stratified (i.e. light water above dense water). A corollary to this rule is that fluid likes to move along isopycnals rather than across, so intrusions move along isopycnals. This makes density a poor tracer. Salinity however has no such constraint (it affects density of course, but these affects can be compensated by temperature changes). I think in this case salinity is acting as a tracer for the low oxygen water mass.
Thanks for the explanation, Kipp. The number of years since my PO class are shamefully evident! Would love to get your impressions of the TS plots sometime.
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