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Re: Calculate sea ice extent area from sea ice thickness data



Hi Ming,
You can do this kind of thing by defining a "mask". Define a mask which is 1 for the values of thickness that you want to keep in your sum. The mask has missing values everywhere else. You can use an integrating transform to add up all the area - if the grid is in terms of latitude/longitude then the latitude correction is automatically taken care of by the transformation.

yes? LET icemask = IF hic GT 0.1 THEN 1
yes? LET ice_extent = icemask[X=@DIN,Y=@DIN]

There are some more examples of this in the FAQ, "Averaging/integrating over irregular regions in Ferret"
http://www.ferret.noaa.gov/Ferret/FAQ/analysis/avg_integ_irreg.html

Ansley

Ming Yang wrote:

Hi, folks
I have a netcdf file which contains a variable HIC describing the
global sea ice thickness. I am thinking to calculate the corresponding sea
ice extent area from this variable by ferret. My algorithm is like this.
Whenever the sea ice thickness at certain point is greater than certain
value (for example, 0.1m), I assume the whole area represented by this
point is covered by sea ice. Then I sum up all of them to get global sea
ice extent area. Do you guys know how to do this in ferret? Thank you for
your help.


Ming









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