Re: [idvusers] How do you time step 3-hourly NARR data in the IDV?


With the latest nightly build (IDV 3.0u2), the problem of using the Merge Time Sequences formula has been fixed, so Tom's and my suggestion on using that will now work if you load in each file as a separate data source.

I thought that one could download and merge all the files togther, but I got a lot of warnings about time coordinates not matching when I did that (although I did get the right times for the 3D fields).

Thanks, John, for looking into this. We'll look forward to the grib improvements in 4.3.


On 1/3/12 7:05 PM, John Caron wrote:
Mike, there are some very serious issues with the way versions of the
TDS before 4.3 handle GRIB, especially time coordinates. That server is
running 4.1, so its likely affected.

Also theres no way to do reliable client-side aggregation (ie in the
IDV) on remote GRIB datasets. The best that can be done is to wait until
4.3 is done, then convince Nomads to upgrade to it and add server side
aggregations. The good news is that we are working closely with NCDC and
Im sure they will be willing to upgrade when its ready.

We may be able to do something better in the future on the client, but
that the way things are now.


On 1/3/2012 9:43 AM, Mike Umscheid wrote:
Thanks for the reply Tom,

I am not having any luck with 2 or 3... but it does sound like I need to
investigate option 1 as I am not all that familiar with NCML in combining
datasets. The NARR data I have been using is straight from the NARR
catalog through the IDV ( So I guess
what I would need to do then is save the individual hourly dataset as a
local grid (*.nc) and then use one of the available tools (I see
called ToolsUI?) to merge the files into one netCDF?

Mike U

On Tue, Jan 3, 2012 at 9:50 AM, Tom Whittaker<whittaker@xxxxxxxx> wrote:

Hi Mike...

The display rule is that if the data object has only one time, then it
is displayed along with all other "time steps"; hence, since both 18z
and 21z data have just one "time", they are displayed together.

I'm not familiar with the NARR data or how you are loading it, but
there are a couple of ways to make individual time period data be

1. using NCML to logically combine times
2. using the Chooser and picking more than one time/file using
SHIFT+click or CTRL+click
3. using the Formula under "Miscellaneous -> Make a time sequence from
single time grids"

Hope this helps.


On Tue, Jan 3, 2012 at 9:13 AM, Mike Umscheid<mike.umscheid@xxxxxxxx>
IDV Users,

I'm not sure how many of you interrogate NARR datasets on the IDV, but
doing more of it now through the IDV using bundles and ISL scripts. One
big limitation I am finding is that I cannot time step/animate through
than one data file on the Map View pane. For instance, if you load in
fields from an 18z file and then also a 21z file, the IDV just displays
21z data right on top of the 18z data. How do you configure the IDV
that for these hourly dataset files you can create animations and step
and forth through various times? Any help/guidance is appreciated!
Mike U
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Tom Whittaker
University of Wisconsin-Madison
Space Science& Engineering Center (SSEC)
Cooperative Institute for Meteorological Satellite Studies (CIMSS)
1225 W. Dayton Street
Madison, WI 53706 USA
ph: +1 608 262 2759

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