[IDV #COT-972342]: Loading 3D Fields in IDV

Hey Josh-

> I've never used anything other than ARWpost.  I tried to find wrfpost on the
> web, but couldn't find a place to download it from.  Is that the one you are
> talking about that keeps the units?  That might be much better for use with 
> the
> IDV for me since converting to a Vis5D file seems to create problems 
> sometimes.

Here's a link to information on WRF-POST:

http://www.dtcenter.org/wrf-nmm/users/docs/user_guide/WPS/users_guide_nmm_chap7_v1_WPS.htm

You can download it from:

http://www.dtcenter.org/

Don

> 
> --Josh G.
> 
> On Fri, Apr 11, 2008 08:02 PM, "Unidata IDV Support"
> <address@hidden> wrote:
> >
> Hi Josh-
> >
> >> I suspect the post processing issue is the solution.  Whenever I converted
> >the
> >> data over to Vis5D format using ARWpost, the 3D fields loaded pretty
> >quickly.
> >> And you are right on with the derived parameters taking the longest amount
> >of
> >> time.  So that answers the original question.
> >
> >Okay.  That's what I figured.
> >
> >> The only issue with converting using ARWpost is IDV won't create a
> >topography
> >> from the ARW height variable once it's converted from NetCDF to Vis5D.  It
> >> comes up with an error that says something about the units being unknown.
> >I
> >> think this is an issue with Vis5D.  Do you have any suggestions on that by
> >> chance?
> >
> >When you say height, are you talking about geopotential height or
> >surface height.
> >
> >Can you provide the Vis5D file on an FTP or HTTP server for me
> >to take a look at?
> >
> >> Thanks very much!
> >
> >Have a good weekend.
> >
> >Don
> >
> >> On Fri, Apr 11, 2008 06:01 PM, "Unidata IDV Support"
> >> <address@hidden> wrote:
> >> >
> >> Hi Josh-
> >> >
> >> > Full Name: Josh Gelman
> >> > Email Address: address@hidden
> >> > Organization: PSU
> >> > Package Version:
> >> > Operating System:
> >> > Hardware:
> >> > Description of problem: Hello,
> >> >
> >> > Whenever I try to load a 3D field in IDV using a WRF ARW dataset, the
> >time
> >> >it takes to load is extremely slow (up to a half hour
> >sometimes).
> >> >For 2D fields it's nearly instantaneous.  This only seems to happen
> >with my WRF
> >> >ARW datasets.  The rest load pretty fast.  I am curious if there is
> >any way to
> >> >resolve this issue?
> >> >
> >> >When you say "only seems to happend with my WRF ARW
> >datasets", are
> >> >you
> >> >comparing them to standard (e.g. GFS) grids or WRF NMM
> >datasets?  Are
> >> >you
> >> >loading single levels or are you loading in the entire volume and
> >trying
> >> >to do cross sections or isosurfaces?
> >> >
> >> >The problem with the WRF netCDF files (NMM and ARW) is that
> >they
> >> >grids are staggered.  To handle this, we need to hold both the
> >> >native grid domain and a transform to pressure in memory.  So
> >> >at the outset, just loading in the grid is a double wammy.  Your
> >> >performance is going to depend on the size of the grid and number
> >> >of timesteps as well.  What are the dimensions of your grid?
> >> >Any of the derived parameters have an added overhead of resampling
> >> >the data from one point of the domain to another.  For example,
> >> >wind speed or wind vectors require resampling the V to the U domain.
> >> >Those are grids that I've seen really bad performance on and the
> >> >culprit is the resampling.  Straight parameters like U wind or
> >> >vapor pressure shouldn't take much longer than a standard unstaggered
> >> >high resolution NAM grid.
> >> >
> >> >In general, we suggest that users postprocess the WRF netCDF data
> >> >using WRF-POST or the Vis5D converter.  These destagger the grids
> >> >and output them on pressure levels as well as compute standard
> >> >parameters like  sea level pressure.
> >> >
> >> >There are also some steps you can take to improve performance
> >> >listed at:
> >> >
> >>
> >>http://www.unidata.ucar.edu/software/idv/docs/userguide/misc/PerformanceTuning.html
> >> >
> >> > The computers I'm running IDV on have 16 GB of memory and 3 GHz 
> >> > processor speed.
> >> >
> >> >When the data is loading slowly, is the memory monitor showing that
> >> >you are maxing out on memory?  Have you increased the default
> >> >amount of memory that the IDV gets allocated?  If not, see the
> >> >performance tips above.  Depending on your operating system, you'll
> >> >only be able to use a subset of the total memory.
> >> >
> >> > Thanks for any suggestions.
> >> >
> >> >I'm guessing that the slowdown is due to resampling which is painful
> >> >for the staggered grids.  But if you are seeing really slow loading
> >> >on one of the main fields in the grid, then there is some other
> >> >issue.
> >> >
> >> >Don Murray
> >> >
> >> >Ticket Details
> >> >===================
> >> >Ticket ID: COT-972342
> >> >Department: Support IDV
> >> >Priority: Normal
> >> >Status: Open
> >> >
> >> >
> >> >
> >> >
> >>
> >>
> >>
> >>
> >>
> >>
> >
> >
> >Ticket Details
> >===================
> >Ticket ID: COT-972342
> >Department: Support IDV
> >Priority: Normal
> >Status: Open
> >
> >
> >
> >
> 
> 
> 
> 
> 
> 


Ticket Details
===================
Ticket ID: COT-972342
Department: Support IDV
Priority: Normal
Status: Open