Re: regriding, masks etc

[Ansley Manke <ansley@xxxxxxxxxxxxx>]

Hello Josef,
If I understand your question correctly, you want to
regrid a land mask to a coarser grid.  Here is an example
using the Etopo datasets (which you have with the Ferret
distribution, and might use to create a mask as well)

yes? use etopo120
yes? use etopo60
yes? let rose120 = rose[d=1]

! generate a fine mask which we will regrid

yes? let mask60 = if rose gt 0 then 1 else 0
yes? let coarsemask = mask60[g=rose120]         ! regrid to the coarser grid
yes? shade coarsemask

The regridding transform results in intermediate values along the
coastlines.  We can  re-mask that,  making the intermediate values
take on either 1 or 0...

yes? let newmask = if coarsemask ge 0.5 then 1 else 0
yes? shade newmask

-Ansley Manke

Jozef SYKTUS wrote:

> Hi,
>
>    I have 2 files one at say ~75 km grid resolution and another at 5km
> resolution.
>
> I would like to use 5km file which is basically land/sea mask to derive a
> new data file at 75 km which would have all ocean points mask out.
> Is it possible to create a new land/sea mask at ~75km from those two
> files? Is there any other method of creating land/sea mask at ~75km ?
>
> I have enclosed those two files?
>
> I would appreciate your help.
>
> Jozef
>
> Jozef Syktus -- Senior Research Scientist
> Department of Natural Resources & Mines
> Climate Impacts and Natural Resource Systems
> QCCA Bldg. 80 Meiers Rd.
> Indooroopilly Qld 4068 Australia
> ---
> Phone:61 7 3896 9730
> Fax:  61 7 3896 9843
> e-mail:jozef.syktus@dnr.qld.gov.au
> http://www.dnr.qld.gov.au
> ----
> Project:
> Experimental Seasonal Climate Prediction Modelling
> Queensland Centre for Climate Applications
>
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>                             Name: AusmaskD.nc.gz
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--
Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246