Varying salt concentrations in the oceans

[DennisS]

Here's a profile near the equator-North and South along the 95W line longitude showing salinity form the surface down to 1000 meters

http://www.pmel.noaa.gov/tao/kaimi/gp605/95w_sal.gif

There are a lot more profiles in there if you are interested.

 

[AXL72]

:doh:

well, i thought it collected in the lower layers or whicked up or something. I am talking 5 to 11 ft of ice. You may be right. Maybe it is permafrost that collcts brine?

Well the data I provided is correct. Perhaps scratch my "doh" on the sea ice remark.

 

[Thalassamania]

Good explanations are to be found here: UCAR: Oceans

 

[Charlie99]

Try http://www.arctic.noaa.gov/essay_wadhams.html for a good explanation of the details on how sea ice forms, including how it makes the transition from an average of 10psu as new ice to 1-3psu after going through a one year cycle of partial melt and refreeze.

As the sea water freezes, it tends to expel the salts. Some of this will end up in brine channels, but overall the sea ice is less salty.

Lot of interesting tidbits, including the fact that at the salinity of the oceans, that the density of water continues to increase as temperature decreases, all the way down to the sea water freezing point. (Fresh water hits maximum density at about 4C, with very significant affect on how lakes freeze.)

Another good survey of sea ice formation is http://seis.natsci.csulb.edu/rmorris/seaice/form.htm

 

[FredT]

The water mass can be visualized as a layer cake built of layers consisting of several different densities of water.
As salt increases density increases at the same temperature.
As temperature increases density decreases at the same salinity.
The top layer in the cake will always be the least dense water mass in the stack.
For "surface water" (the type we dive in) to be saltier than it was it has to also be warmer or it would sink, assuming the next layer is the nearly the same density.

OTOH really cold water can float on warm water if there is a significant salinity delta. Anyone who has been diving at the mouth of MS river in the spring has first hand experience with that. The freezing nasty brown river water running down from cold country floats on the much cleaner and warmer water of the open Gulf.

BTW the density differences between layers we are talking about are right, often WAY right, of the 6th decimal place.

FT

 

[FredT]

If water (ocean) levels are rising, then the salinity would decrease.

Please note that sea levels are NOT rising, despite all the PC hype. There are a few areas where the land is subsiding, most notably at river deltas located on failed spreading centers, but most deltas subside a bit simply due to the mass of sediments being desposited there from the hgh country every year.

If sea levels were actually rising the water levels at tectonically sable low islands would also be rising. The most recent Data shows it is not.

The thing that will cause the levels to rise is a worlwide case of the "galloping glaciers" where grounded ice inland in the arctic and antarctic starts a rapid movement into the sea. This will raise the sea level in a step fashion over a relativly short geologcial time frame. The coversion of grounded ice to floating sea ice will also rapidly cool the earth due to increased reflectance and tend to increase the ice mass on the high arctic and antarctic areas again. This is a sort of feedback loop that operates to stabilize the climate within a fairly narrow specific range, and will continue to operate as long as the Bearing Sea remains wet and allows surface water transfer from the Atlantic to the Pacific basins through the Arctic Ocean. If you look at the historic climate in relation to that waterway's condition and the historic orientation of the earth's magnetic field you'll see some pretty amazing things.

FT