[ncl-talk] Interpolation-subsetting strategy

[Jennifer Krauel]

I'm new to NCL and have been studying all the reference material I can
find. There are plenty of sample scripts, but many of them raise more
questions than they answer. I'm hoping this is the best place to go for
some answers.

I need to access data from NARR, but only from a single lat/long point. I
need temperature and wind (U,V) at 100m intervals from 50m up to 3000m,
which I'll export to a csv file. This sample script is close to what I
need, except I need many more vertical points:

https://www.ncl.ucar.edu/Applications/Scripts/narr_7.ncl

The script first interpolates vertically (int2p_n_Wrap), then curvilinear
to rectilinear (ESMF_regrid_with_weights), then to specific points
(linint2_points_Wrap).

Is there a reason for this order? Won’t it take a long time to do vertical
interpolation on the whole file if I just want one point? I will need these
data from the 3h intervals over about 9 months, so efficiency is going to
matter. I found some information about using masks with ESMF weight files
to reduce the area for regridding, so why not do that first and mask out
all but an area around the desired point? And how big of an area would I
need? I haven't found any actual scripts that do this explicitly for
geographic subsetting, so I am not sure if it is a good idea.
https://www.ncl.ucar.edu/Applications/ESMF.shtml

Thanks for any advice you can give me!
Jennifer
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