Re: IDV 2.1: Plotting Level II radar data from a local file

Hi Dave-

I know Jeff answered you personally on this, but I'm replying to
the list for the benefit of others who've seen your post.

First, this is a bug in 2.1 but has been fixed in the latest
nightly/beta release at:

The problem is that older Level II files have no geolocation
information in them (i.e. where they are). In previous versions
of the IDV, we used the chooser to force the location instead
of looking in the file.  When we moved to the new Common Data
Model (CDM) way of reading the Level II files, this functionality
got lost.  By default, if there is no geolocation information,
we set the location of the radar to 0 lat/ 0 lon.

You have a couple of options with version 2.1:

- After loading in the dataset, double click on the Data Source
in the Field Selector to bring up the Properties dialog.  Select the
correct location from the list.  Then, plot your data.

- use the old way of reading in the data by clicking off the
"Use CDM" checkbox in the Level II selector.  This eliminates
one step, but we have found that the displays are sometimes
not correct.

One more note is that there are problems with the CAPPI displays
for Level II data in versions 2.1 and earlier.  We have fixed that
also in the latest releases.

Don Murray

Dave Dempsey wrote:
IDV users,

We have some Level II radar data on a local file system and are trying to plot it using the IDV (v.2.1 on various Macs), following the instructions in the Users Guide. We can plot the data themselves OK, but the map background is centered at 0 degrees N and 0 degrees E (in Africa's Gulf of Guinea) no matter what we've tried.

The data are in a local file named KOAX20040522_011610. (I've also tried renaming it KOAX_20040522_0116.) I've tried placing the file in a directory called KOAX and also in a directory called OAX. The file (and a number of others like it) are accessible on the Web at:

Here's the procedure(s) we've tried:

(1) New Data Source > From the File System. In the "FIles" list, click on "Radar". Select "Omaha/Valley" from the "Radar Location" menu. Navigate to the directory containing the data file. Select the file. Click on the "Add Source" button.

(2) In the Dashboard, under "Data Sources", I get the entry "Level II Radar Data (XXXX)", so it appears that the IDV doesn't know where the station is, even though it was specified using the "Radar Location" menu and resides in a directory called KOAX (or OAX). In the "Fields" window a list of fields appears. Selecting a field and a display type and clicking on the "Create Display" button produces a display. It is located in the Gulf of Guinea.

On the Map Display - One Pane" window, under "Displays", the field is identified as "XXXX Reflectivity - 2D Radar Sweep View". Clicking on this name produces a Dashboard dialog window in which the station is correctly identified as "OAX Lat: 41.3 Lon: -96.4 Alt: 350.0".

None of these problems occur if I access Level II data via an ADDE server.

Can anyone spot what we might be doing wrong? (I think I've been here before but can't remember the answer!)

-- Dave

*   Dr. Dave Dempsey                        |       ^   ___       \|/     *
*   Dept. of Geosciences                    |  ) ^     /||_||\    --0--  *
*   San Francisco State University   | )  )    /  ||_||  \    /|\     *
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Begin forwarded message:

From: John Monteverdi <montever@xxxxxxxxxxxxx>
Date: March 13, 2007 3:59:37 PM PDT
To: Dave Dempsey <ddempsey@xxxxxxxxxxxxxxx>
Subject: Bug in idV...running on Pentium Macs


I think I encountered a pretty serious bug in iDV (and Nexrad Radar Viewer) running on "tornado" but not on my home desktop (which is not Pentium).

I downloaded Level II and Level III data sets for February 25, 2004 for KMUX. On idv these data sets misplot geographically. The Level II stuff plots at too small a scale relative to the map background (meaning, echoes over SF appear over San Mateo). On Nexrad Radar Viewer, the option to "smooth" the radar crashes the software.

Both idv and Nexrad Radar Viewer run OK and plot OK at home.

Thus, I think the issue might be with the Pentium chip, and/.or Java running natively on a Pentium Mac.


Don Murray                               UCAR Unidata Program
dmurray@xxxxxxxxxxxxxxxx                        P.O. Box 3000
(303) 497-8628                              Boulder, CO 80307