Senya,<div>I had not noticed the duplicate 164 values before, but I now see it when I 'q ctlinfo' on the LTM file. Thanks for pointing that out, and for the CTL file suggestion.</div><div>Stephen<br><br><div class="gmail_quote">
On Wed, Feb 23, 2011 at 4:03 PM, Semyon Grodsky <span dir="ltr"><<a href="mailto:senya@atmos.umd.edu">senya@atmos.umd.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Stephen,<br>
lon from LTM file is corrupted. It has two 164 values, one of which is<br>
supposed to be 166. That is why lon from LTM is set to levels instead of<br>
linear when opening by sdfopen.<br>
The easiest way to avoid this problem is to write the CTL for LTM data.<br>
--Senya<br>
<br>
<br>
On Wed, 23 Feb 2011, Stephen McMillan<br>
wrote:<br>
<div><div></div><div class="h5"><br>
> Recently I wrote the Webmaster for the 20th Century Reanalysis V2 data<br>
> plotting pages, regarding grid incompatibility between the following two<br>
> data files:<br>
><br>
> Monthly means:<br>
><br>
> <a href="ftp://ftp.cdc.noaa.gov/Datasets/20thC_ReanV2/Monthlies/monolevel/air.sig995.mon.mean.nc" target="_blank">ftp://ftp.cdc.noaa.gov/Datasets/20thC_ReanV2/Monthlies/monolevel/air.sig995.mon.mean.nc</a><br>
> Monthly longterm means:<br>
><br>
> <a href="ftp://ftp.cdc.noaa.gov/Datasets/20thC_ReanV2/Derived/Monthlies/monolevel/air.sig995.mon.ltm.nc" target="_blank">ftp://ftp.cdc.noaa.gov/Datasets/20thC_ReanV2/Derived/Monthlies/monolevel/air.sig995.mon.ltm.nc</a><br>
><br>
> I can plot the "air" variable from each without a problem, but when I<br>
> subtract the longterm mean from the mean to create an anomaly, I get a grid<br>
> incompatibility error. The means file was sdfopened first, the longterm<br>
> means file second. For example, doing Aug1969:<br>
><br>
> ga-> d air(time=aug1969)-air.2(t=8)<br>
> Operation error: Incompatable grids<br>
> Dimension ranges aren't equivalent<br>
> Dimension = 0<br>
> 1st grid range = 1 181 2nd = 1 181<br>
> Error ocurred at column 29<br>
> DISPLAY error: Invalid expression<br>
> Expression = air(time=aug1969)-air.2(t=8)<br>
><br>
> My workaround is to first regrid the longterm mean to a 2-deg linear grid,<br>
> but it would be preferable to do a simple difference as in example above.<br>
> The Webmaster suggests it's a GrADS bug. His response:<br>
><br>
> "The grids are identical. This appears to be a GrADS bug. No such<br>
> problem obtains in NCL. GrADS appears to insist that the longitudes<br>
> in the LTM file don't wrap, even when they are manually set to do so.<br>
> We have run every test we can think of, including dumping the longitudes<br>
> from both files and comparing them. They are the same."<br>
><br>
> I have tried this with OpenGrADS versions 2.0.a7.oga.3 and 2.0.a9.oga.3 with<br>
> equal results, but have not tried with the COLA version of either. Can one<br>
> of the developers or other user shed some light on this?<br>
><br>
> I am using GrADS on a Windows XP.<br>
><br>
> Stephen McMillan<br>
><br>
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<br>
-----------------------------------------------------------<br>
Semyon Grodsky<br>
Computer and Space Science Building (Bldg. #224), Room 2409<br>
Department of Atmospheric and Oceanic Science<br>
University of Maryland<br>
College Park, MD 20742<br>
<br>
Phone: 301-405-5330<br>
Fax: 301-314-9482<br>
E-mail: <a href="mailto:senya@atmos.umd.edu">senya@atmos.umd.edu</a><br>
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