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Re: Plotting vertical light extinction



Hello,
You can define a vertical axis describing the depth with the
DEFINE AXIS command.  You can either use negative values
for the depths, or use the /DEPTH qualifier to indicate that the
Z values measure depth.  If your depths are at irregular
intervals, use the DEFINE AXIS/FROM_DATA qualifier.

Ferret has an EXP function which will let you define the
irradiance function.  The outline of what you want to do is
something like the following.  I assume lo and k are constants;
I do not know their values, but I will show how you can set
them.  Since K already has special meaning in Ferret, I will
use K0

   yes? LET k0 = 0.1
   yes? LET lo = 17.
   yes? DEFINE AXIS/Z=0:100:5/DEPTH  zax
   yes? LET zz = z[GZ=zax]
   yes? LET irr = lo * EXP(-1*k0*zz)
   yes? PLOT irr

I hope this will get you started.

Ansley Manke

M Manizza wrote:

Dear Ferretters.
I want to plot the vertical profile of the light extinction in the ocean.

I need to create an array with negative depth fro 0 to -100

And then use to calculate the irradiance at any depth by the equation I(z) = Io * e(-kz) as first stage, and then

use the Paulson & Simpson Equation wich has 2 exponential terms.

Cheers, Manfredi

--------------------------------------------------------------

Manfredi Manizza

MPhil./PhD. student

School of Environmental Sciences

University of East Anglia

NorwichUK

NR4 7TJ

email addresses: m.manizza@uea.ac.uk,

mmanizza@bgc-jena.mpg.de

--------------------------------------------------------------

--
Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246
 

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