Question On Ocean Analysis Of Enthalpy

We have posted the two guest contributions

Guest Post “Calculating Moist Enthalpy From Usual Meteorological Measurements By Francis Massen

Comments On The Moist Enthalpy Calculation By Anthony F. Fucaloro

As part of a very informative exchange of follow on e-mails between Anthony F. Fucaloro and Francis Massen , which will be posted as a Comment/Reply when ready,  I was asked the following question by Anthony Fucaloro.

 “Dr. Pielke, who is herein copied, has repeatedly stressed the importance
 of ocean enthalpy in climate studies and I pose the following question to
 him. Do ocean researchers take into account the decrease in constant
 pressure heat capacity of water with increasing pressure (i.e. ocean

In response to this question, I e-mailed to Josh Willis, who is an expert on this subject, for his reply. I have posted below his answer, with his permission.

“Hi Roger,

In answer to the question, I do use a pressure dependent heat capacity based on the UNESCO 1983 polynomial approximation for the equation of state of sea water.  However, I have done numerous tests over the years and found that if I replace that with a constant approximately equal to 4×10^3 J kg^-1 C^-1, then I get answers for global ocean heat content that are indistinguishable. The value of heat capacity really only varies by a percent or two in the upper ocean and temperature variations, as well as errors in the temperature field are much more important for determining ocean heat content and its errors than using the correct heat capacity.

So the answer is, yes, I do account for pressure dependent heat capacity, but if I didn’t I would get essentially the same answer.


ps.  feel free to post this reply!  -j”

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