how to get density equation in ROMS？

[XMUZSM]

Hi，does anyone know that how to get the density equation in ROMS ? Can I use linear EOS function combining the tracer equations (temp and salt) to derive the density equaiton when I define NONLINEAR_EOS?

[wilkin]

It is documented, with references, in ./Nonlinear/rho_eos.F

[XMUZSM]

Hi, I can find how to compute density in rho_eos.F, but how about density equation?
I mean drho/dt= advection + diffusion

[arango]

This must be a first in this forum. You must read about ocean observations' history, geophysical fluid dynamics, and their governing equations. We cannot measure the density of seawater accurately. So, our classical physical oceanographer's ingenuity was to design and build instruments that measure temperature (heat content) and salinity (dissolved matter content) more accurately as a function of pressure at smaller/larger spatial and temporal scales. Therefore, as closure, we needed an equation of state, which is a mathematical formula that relates temperature, salinity, and pressure, ρ(T, S, P). It also computes the various related quantities required for several numerical schemes, as shown in rho_eos.F. The original expansion coefficient polynomials for these relationships were calculated with an abacus before the age of calculators and computers. It is a fascinating part of the golden era of the evolution of physical oceanography.

There are several good books on Ocean Modeling that you could study and read. For example, The Evolution of Physical Oceanography by Warren and Wunch honors the career of Henry M. Stommel, which I have the pleasure of meeting and attend to his seminars before his passing.