Equation of State

seawater_density!(rho, T, S, p)

In-place, element-wise computation of density on arrays. Arrays must have the same shape (nlon, nlat, nz).

seawater_density(T, S, p)

UNESCO (Millero & Poisson 1981) in-situ seawater density.

Arguments

• T : potential temperature (°C)
• S : salinity (psu / g kg⁻¹)
• p : pressure (bar; 1 bar ≈ 10 m depth)

Returns

• density ρ (kg m⁻³)

seawater_density_insitu(T, S, z)

Convenience wrapper: computes pressure from depth z (negative downward, m), then calls seawater_density. Uses hydrostatic approximation p ≈ ρ₀·g·|z|/1e5 bar.

compute_pressure!(p, T, S, grid)

Integrate hydrostatic pressure downward into the water column.

p, T, S are Field{Center, Center, Center} on grid. Uses Oceananigans k-convention: k=Nz = surface layer, k=1 = deepest layer. Immersed (below-bathymetry) cells are set to p = pressure of the nearest active cell above them, so horizontal pressure gradients at the seafloor boundary remain small (avoids spurious velocities from the FG solve). Returns p with halos filled.