Re: [netcdf-java] Questions about handling dimensionless coordinates


>  Just thought of another question – is it possible to find
> out what the min-max range of “natural” coordinates is, or would I have to
> perform the transformation (theoretically for every timestep) and search the
> returned 3D array?

For ocean models, to compute the min-max Z range for the dataset, you
would need to read the max value over all time of the ocean surface
variable, and then find the deepest depth of the depth (bathymetry)
variable.  So you need to read a 3D surface field (Y,X,T) and the
depth field (X,Y), but you wouldn't need to do any of the vertical

> I suppose that I could do the transformation for one
> timestep only and assume the range won’t be very different for other
> timesteps since the free surface (or surface pressure) isn’t likely to vary
> too much?

Yes, you could probably get away with that.
> Rich – yes, I probably could use the IDV routines although that means
> another dependency for the sake of one routine, plus I need to look at how
> to instantiate the IDV objects correctly in all cases.  Just requires a bit
> more thought.

Okay, well, at least use the NJ routines to return the vertical
coordinate info (let it do the transformations for you).   Nearest
neighbor is way too crude for vertical interpolation.  Linear will be
fine for most visualization, and easy to implement.  For each x,y,
just find the levels below and above the requested z value and
linearly interpolate between them.

Dr. Richard P. Signell   (508) 457-2229
USGS, 384 Woods Hole Rd.
Woods Hole, MA 02543-1598

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