interpolator?

[Dongxiao Zhang <dzhang@xxxxxxxxxxxxxxxxxxxx>]

Hi all,

I have to interpolate mooring measurements in a 2-d section along time
axis with 6000 time steps. For example, the vertical section looks like:

 x   -99.  -99.  x  x  x  o  x

 x    x    -99.  x  o  x  x  x

 x    x     x    x  x  x  o  x

 x    x     x    x  x  x  x  x

x----good data all the time
-99.----some time good data, some time bad data(no data)
o----no data at any time

Have any body done the similar thing with Ferret? Or any body know how to
do it by Ferret? Two Ferret tools can interpolate the scattered data, but
each one gives me problem. 

(1) transformation linear interpolation filler
@FLN:n fills holes(values flagged as invalid) by linear interpolation, but
according to Ferret User's Guide, all transformation are normally computed
axis by axis, except @din and @ave(they are computed simultaneously on
axes). So, in my case, [x=@fln:n, z=@fln:n] first apply on x, then all
holes can be filled, no vertical profile information can be taken into
account. For [z=@fln:n,x=@fln:n], no x direction information can be taken
into account by interpolator.  This @fln:n can only work well on 1-D
problem. Am I right? 

(2) objective.jnl grids (X,Z,value) triples onto a grid of specified
resolution using objective analysis by Laplacian and spline interpolation.
 This works on 2-D problem, by using REPEAT, it is easy to use it along
time axis for 6000 times. But in my case, on -99. locations, some time we
have data, some time we have not. So I have to make several thousands sets
of (X,Z,value) triples, obviously this is not a good way. If I flag the
-99. as invalid or missing value when no data(by this way I can make a
netCDF data file on one single X,Z grid set, with the holes need to be
filled assigned as invalid or missing value), will the objective.jnl fill
the holes as @FLN:n do? 

I would like to try both linear and spline interpolation. I appreciate any
suggestion and correction on my understanding on @FLN:n.

Best Regards,

Dongxiao
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Dongxiao Zhang
Division of Meteorology and Physical Oceanography
Rosenstiel School of Marine and Atmospheric Science
4600 Rickenbacker Causeway
Miami, FL 33149
Phone  : (305)361-4806
Fax    : (305)361-4696
Office : MSC Room 309
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