Depth axis to Density axis

Question:

How can I convert between two depth axes, for example from depth to density?

Example:

I want this image on a density scale [Output Graphic]

Solution:

The ZAXREPLACE( salt, sigma, z[gz=axden]) function is designed to do this conversion.

Argument 1 is the field of data values, say temperature on the "source" Z-axis, which is depth in this case. The second argument, ZVALS, contains values in units of the desired destination Z axis (ZAX) on the Z axis as V for example, density values associated with each vertical depth. The third argument, ZAX, is any variable defined on the destination Z axis, here "Z[gz=zaxis_name]" is used. For example:

      ! Convert between a depth and density Z axis using the function ZAXREPLACE

      yes? set dat ocean_atlas_annual

      ! Define density sigma, then density axis axden
      yes? let sigma=rho_un(salt,temp,0)-1000
      yes? define axis/z=21:28:.05 axden

      ! Regrid to density
      yes? let saltonsigma= ZAXREPLACE( salt, sigma, z[gz=axden])

      ! Make Pacific plot, labelling the vertical axis as density.
      yes? fill/y=0/x=120e:75w/vlimits=28:21:-1/set_up saltonsigma
      yes? ppl ylab density
      yes? ppl fill 










 

Last modified: April 02, 2001