The steps you will need are:
-- Regrid U and/or V so they are on the same x-y-z grid.
-- Use the zaxreplace function and define new variables, say U_phys
and V_phys on a depth axis. See ZAXREPLACE
in the Users'
Guide for how to do this, also the FAQ
on sigma coordinates.
-- Plot the vectors U_phys, V_phys in an x-z or y-z plane
-- Overlay a plot of the bottom depth
Here is an outline of the Ferret commands:
! define a depth axis and the function for translating to depth.
define axis/z=... depthax !whatever your depth axis is
let zvals =
!function relating sigma coordinates to depth
! convert U and V to the depth axis. Regrid V to the grid
of U.
let U_phys = zaxreplace(u, zvals, z[gz=depthax])
let V_phys = zaxreplace(v[g=GFS3], zvals, z[gz=depthax])
! plot the vectors for a value of Y
VECTOR/y=20n U_phys, V_phys
! plot the bottom depth
PLOT/over/y=20n depth
You could also use the script fill_between.jnl to fill in the area under
the bottom-depth curve. See the FAQ, "How
can I fill between two curves?"
for how to do this.
I hope this is enough to get you started! Ansley Manke
maria lemos_diaz wrote:
Hello...
I am having big problems in plotting vectors in a sigma coordinate system.
I need a vertical vector plot with bottom topography.
In the documentation I only found that I must give 2-dimensional grids
for the specification from each index pair, but no examples.
In my case I have:
H (bottom depth) on grid GKX3 with i=1:10 and j=1:66
U on grid GFS3 with i=1:9 , j=1:66, k=1:14, l=1:101
V on grid GFS4 with i=1:10, j=1:65, k=1:14, l=1:101I appreciate every help...Thanks!!
Maria
--
Ansley Manke Pacific Marine Environmental Laboratory Seattle
WA (206)526-6246