RE: [ncl-talk] calculating w from omega and gsn_csm_pres_hgt_streamline

Hi Mary, welcome to August!, well here at least...

My attempts to plot streamlines following stream_8.ncl and a thread with Adam (see message sent Fri, 07 Sep 2007 09:41:58) fails. I'm not sure if it is the cacuclation of W or the plotting part. However, in the plotting part I see some very weird arrows (even if W was wrong it should behave better) and so suspect it is in the plotting part. That is why I broke it up into 2 steps and I gave the full step to show the full process (and if yo download the data as shown below it can also be run). The previous thread on the topic almost covered my exact problem and even used some standard Ncep data like me but it didn't seem to have a final solution. The inputs into the W calculation are directly from the reanalysis data and are very large (another reason why I supplied , however, are directly from the NCEP R-1 archive and so easily copied. I think many folk would be interested in plotting streamlines from a generally available set of data like the NCEP reanalysis and as no vertical interpolation is required it should be more easy than the stream_8.ncl example (in theory!)...

The inputs to hadley_setup.ncl are readily got with

wget ftp://ftp.cdc.noaa.gov/Datasets/ncep.reanalysis/pressure/air.2008.nc
wget ftp://ftp.cdc.noaa.gov/Datasets/ncep.reanalysis/pressure/omega.2008.nc
wget ftp://ftp.cdc.noaa.gov/Datasets/ncep.reanalysis/pressure/vwnd.2008.nc

Many thanks,
Mark.
________________________________________
From: Mary Haley [haley@ucar.edu]
Sent: Saturday, 1 August 2009 3:12 AM
To: Collier, Mark (CMAR, Aspendale)
Cc: Dennis Shea; Adam Phillips
Subject: Re: calculating w from omega and gsn_csm_pres_hgt_streamline

Hi Mark,

This is offline.

I feel like I'm missing part of the message. Can you state what the
problem is so I know where to start looking? That is, are you getting
an error, or do you just have a general question about how to do
something?

--Mary

On Thu, 30 Jul 2009 Mark.Collier@csiro.au wrote:

> Hi,
> I'm looking for some help solving the following:
>
> I've followed the online documentation and messages trying to generate a latitude vs height streamline plot from v and w using NCEP reanalysis files.
>
> I've uploaded 2 scripts
>
> hadley_setup.ncl: generates reduced datasets (including generating W from OMEGA using function OMEGA_TO_W) from raw NCEP files
> hadley_plot.ncl: generate latitude vs height plot using gsn_csm_pres_hgt_streamline
>
> I've put the output file ncep_items.nc from hadley_setup.ncl also onto the incoming area on ftp.cgd.ucar.edu.
>
> I have averaged over a number of times and longitudes in the hope of generating smooth streamlines. I have just used standard functions and procedures with the addtion of OMEGA_TO_W.ncl unchanged.
>
> Regards,
> Mark.
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Received on Fri Jul 31 16:35:14 2009