# Re: WRF_SLP and WRF_INTERP_1d documentation

From: Joseph Zambon <jbzambon_at_nyahnyahspammersnyahnyah>
Date: Thu Nov 03 2011 - 14:55:40 MDT

The two functions are found in the source code under: ni/srv/lib/nfpfor/wrf_user.f, right next to each other coincidentally...

Briefly, here is the final equation to calculate SLP (Note: the 0.01 factor converts to hPa):
SEA_LEVEL_PRESSURE(I,J) = 0.01 * (P(I,J,1)*
+ EXP((2.D0*G*Z_HALF_LOWEST)/
+ (R* (T_SEA_LEVEL(I,J)+T_SURF(I,
+ J)))))

I have attached the subroutines, hopefully it helps to answer your questions.

-Joe

Joseph B. Zambon
jbzambon@ncsu.edu
NC State University
Department of Marine, Earth and Atmospheric Sciences
Jordan 4133

On Nov 3, 2011, at 12:56 PM, Mary Haley wrote:

> Hi Bill,
>
> This question is more appropriate for wrfhelp@ucar.edu, whom I've cc'ed.
>
> If they provide you with some more information, can you post it back on ncl-talk,
> and I'll add it to the documentation if it helps.
>
> Thanks,
>
> --Mary
>
>
> On Nov 3, 2011, at 1:02 AM, Capehart, William J wrote:
>
>>
>> I have a question about the vertical interpolations used in the WRF_SLP
>> and WRF_INTERP_1D functions.
>>
>> Specifically, by which method of extrapolating temperature for the
>> hypsometric ride down to sea level does it use. (e.g.,
>> http://www.crh.noaa.gov/unr/?n=mslp)
>>
>> Similary, I am assuming that the WRF_INTERP_1D uses a straight linear
>> interpolation (as the documentation says) and does so by presuming that
>> the grid spacing in the vertical make such an approach "safe" as compared
>> for example do using the classic isobaric levels we get in traditional
>> GRIB products (1000, 975, 950, 925, 900, 850, 800, 750, 700Š)
>>
>> Also could this information be provided in the online manual pages at
>> www.ncl.ucar.edu? That stuff comes in handy!
>>
>> Thankymuch
>> Bill
>>
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Received on Thu Nov 3 15:01:51 2011

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