[ncl-talk] Problem with calculation of wet bulb temperature

[Bill Ladwig]

Hi Barry,

Modifying the table isn't easy, but if you like to live dangerously, I can
show you where the file is.

When NCL is installed, the file is installed here:

$NCARG_ROOT/lib/ncarg/data/asc/psadilookup.dat


For the source code, it is located here:

{NCL_SOURCE_ROOT}/ni/src/examples/data/asc/psadilookup.dat


There is a brief description at the top of the file that explains how to
read the data in Fortran, but it should give you some idea of how you might
modify the values. As long as you keep the dimensions the same (e.g. 150 x
150), then you can probably shift the table in to your region of interest.
The table is read in when the wetbulb and CAPE algorithms are run, so you
shouldn't have to change anything but the table.  You probably want to make
a copy of this file and store it somewhere else before modifying the values.

Unfortunately, I don't think we have the original code that generated the
table, so you're probably on your own implementing the algorithm from
Bolton. But, it might be buried in the RIP source code somewhere, which is
where the algorithm originally came from.

Hope this helps,

Bill


On Tue, Aug 28, 2018 at 5:39 AM Barry Lynn <barry.h.lynn at gmail.com> wrote:

> Hi:
>
> I live in an area t aht has locations 200 to 400 m below sea-level.
>
> When calling:
>
> twb = wrf_wetbulb(p,t,qv)
>
>
> I get this error:
>
>
> Outside of lookup table bounds. prs,thte=   1100.3168750000000        347.73405695443734
>
>
>
> So, is it possible to expand the lookup table or to return the closest
> value?
>
>
> Thanks Barry
>
>
>
>
> --
> Barry H. Lynn, Ph.D
> Senior Associate Scientist, Lecturer,
> The Institute of the Earth Science,
> The Hebrew University of Jerusalem,
> Givat Ram, Jerusalem 91904, Israel
> Tel: 972 547 231 170
> Fax: (972)-25662581
>
> C.E.O, Weather It Is, LTD
> Weather and Climate Focus
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>
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