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change in Ferret regridding behavior

Hello everyone,
We have found that a change in the regridding behavior with Ferret v5.0 and
later, is causing some confusion.  Some scripts that worked with earlier
Ferret versions will need changes.

In Versions 5+, when the limits of a variable are unspecified,  e.g.  v2[g=v1] the
grid for v2  will default to the full extent of the v1 grid. Previously, it would  become
the size of whatever region of the v2 native grid overlapped with the v1 grid.
In making this change we smoothed out the behavior of important cases like
    sst - sst_climatology[g=sst]

This means that we now need to specify the region explicitly when we want to
keep the old behavior.  So this change has rendered some existing scripts (and
some of the examples in the documemtation) erroneous.   For example, a
sample script in Chapter 10 of the Users Guide must be changed to specify
which slab of the data is being SAVEd.

yes? FILE/GRID=uv_grid1/BAD=-999/VAR="u,v" uv.data1
yes? LET/TITLE="My U data" u1 = u[G=uv_grid]
yes? LET/TITLE="My V data" v1 = v[G=uv_grid]
yes? SAVE/FILE=uv1_5z.cdf/KLIMITS=1:5/K=1 u1, v1       ! specify   /K=1

yes? CANCEL DATA uv.data1
yes? DEF AXIS/Z=25:25:1 zaxis1
yes? FILE/GRID=uv_grid1/BAD=-999/VAR="u,v" uv.data2
yes? SAVE/FILE=uv1_5z.cdf/K=2/APPEND u1,v1               !  specify /K=2

We are working to find any of our examples or documentation that need this revision,
which will be corrrected as soon as possible.

Ansley Manke

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

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