[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

20020718: nmap/dcgrib/Reanlysis




John,

Glad to hear that you are on the cutting edge. I can see 
the template confusion issue that you were having. Also,
the restore function fALL from the operational perspective
isn't a good match for reanalysis. We see new oportunities
at every juncture....but still glad to know that the infrastructure
is capable of handling the data (though the Y2K issue will creep
back for future and past model output that would extend to 2100
or 1800). Hmmmm.....

If you have input data in your files on THTA coordinates,
I would have thought you would have had a pressure grid.
If not, then you should be able to compose the operator with
existing GEMPAK functions:

mul(1013.25,exp(quo(tmpk,thta),KAPPA))

The exp function is S1 ** S2. KAPPA is defined as 2/7 in the 
gfunc description (otherwise you can insert your referred value),
and thta will be a constant for your level. So, you should
only have to specify GVCORD=thta and GLEVEL your thta value
as well.

Hope I'm not confusing the issue here if I'm missinterpreting
the situation.

Steve Chiswell
Unidata User Support







 
>From: John Merrill <address@hidden>
>Organization: University of Rhode Island
>Keywords: 200207182109.g6IL9n903400

>
>--------------8254BC28C149E222B0879F33
>Content-Type: text/plain; charset=us-ascii
>Content-Transfer-Encoding: 7bit
>
>Hello, Steve:
>   We are, happily, now cooking with gas on use of the NCAR/NCEP
>Reanalysis files from the DS090
>in gempak/nmap. Your suggestions helped us determine that nmap can work
>with multiple Analysis
>times in a file, as long as any other files matching the relevant
>file-name template have the same
>structure (analysis times per day, for example). We had unthinkingly
>stored twice-daily files made
>from the CD-ROM together with 6-hourly files from the Mass Store - no
>can do. We did have to
>use the m argument to dcgrib to increase the grid capacity of the files
>to ~2000. And last (so far), we
>had to comment out a GDATTIM=fall line which is present in many of the
>Restore files; when this
>is active nmap "sees" only the last time in the file, and I don't need
>that specification anyway.
>   We have included both isobaric and isentropic levels in the files,
>and my question relates to the
>latter. The variables available are BVSQ, PSYM, PVOR, RELH, TMPK, U/VREL
>and OMEG.
>I'd like to contour the pressure on the isentropic surface, and I
>suppose I have to calculate it.
>I don't see a gempak function to do this. (I note PR_THTA(TMPC,PRES),
>but not its inverse.)
>I'm ready to learn to code the function (p=p0(TMPK/THTA)^^kappa), and
>just wanted to check
>that I've not missed an already-canned variable or command for this. (By
>the way, and probably
>no news to you, the relevant Table for dcgrib works wonderfully. We
>picked off some pretty obscure
>variables from the Reanalysis set, like the Montgomery Stream Function
>(named MNTSF in the
>Reanalysis world), and gempak recognizes it at PSYM. I've not yet
>checked whether the Omega
>on THTA levels behaves as I expect it to, and have really just begun
>working with these fields.
>But overall I am very pleased at how we are progressing with these
>fields, at last.)    John
>
>--
>
>John Merrill                                     Telephone:  401-874-6715
>Graduate School of Oceanography, URI             Fax:        401-874-6898
>
>
>
>--------------8254BC28C149E222B0879F33
>Content-Type: text/html; charset=us-ascii
>Content-Transfer-Encoding: 7bit
>
><!doctype html public "-//w3c//dtd html 4.0 transitional//en">
><html>
>Hello, Steve:
><br>&nbsp;&nbsp; We are, happily, now cooking with gas on use of the NCAR/NCEP
>Reanalysis files from the DS090
><br>in gempak/nmap. Your suggestions helped us determine that nmap can
>work with multiple Analysis
><br>times in a file, as long as any other files matching the relevant file-nam
> e
>template have the same
><br>structure (analysis times per day, for example). We had unthinkingly
>stored twice-daily files made
><br>from the CD-ROM together with 6-hourly files from the Mass Store -
>no can do. We did have to
><br>use the m argument to dcgrib to increase the grid capacity of the files
>to ~2000. And last (so far), we
><br>had to comment out a GDATTIM=fall line which is present in many of
>the Restore files; when this
><br>is active nmap "sees" only the last time in the file, and I don't need
>that specification anyway.
><br>&nbsp;&nbsp; We have included both isobaric and isentropic levels in
>the files, and my question relates to the
><br>latter. The variables available are BVSQ, PSYM, PVOR, RELH, TMPK, U/VREL
>and&nbsp;OMEG.
><br>I'd like to contour the pressure on the isentropic surface, and I suppose
>I have to calculate it.
><br>I don't see a gempak function to do this. (I note PR_THTA(TMPC,PRES),
>but not its inverse.)
><br>I'm ready to learn to code the function (p=p0(TMPK/THTA)^^kappa), and
>just wanted to check
><br>that I've not missed an already-canned variable or command for this.
>(By the way, and probably
><br>no news to you, the relevant Table for dcgrib works wonderfully. We
>picked off some pretty obscure
><br>variables from the Reanalysis set, like the Montgomery Stream Function
>(named MNTSF in the
><br>Reanalysis world), and gempak recognizes it at PSYM. I've not yet checked
>whether the Omega
><br>on THTA levels behaves as I expect it to, and have really just begun
>working with these fields.
><br>But overall I am very pleased at how we are progressing with these
>fields, at last.)&nbsp;&nbsp;&nbsp; John
><pre>--&nbsp;
>
>John Merrill&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp
> ;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Tel
> ephone:&nbsp; 401-874-6715
>Graduate School of Oceanography, URI&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Fax:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
>  401-874-6898</pre>
>&nbsp;</html>
>
>--------------8254BC28C149E222B0879F33--
>