Density at 4 degrees.

Question

Hi,

Why is "Sigma" at 4 degree is nearly 16 (Under the attribute DENSITY)? It is supposed to be approximately zero taking into consideration that it is the temperature of maximum density.

Also, does the code force a linear gradient in density for numerical reasons, even if the temperature is uniform?

Finally, does the code use an equation of state? Because it does not consider inverse stratification stable, and it always forces a situation where warm water must be on top of cold water, even if it is physically denser.

Thanks

Answer 1

Hi,  

The code uses the UNESCO Equation of stat and Sigma is defined as density-1000.

The density equation takes into account temperature, salinity, and pressure.  To get to a sigma of 16 you must either be in deep water or have salinity.

Chris