<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi Luis,<div><br></div><div>You need to describe your variables as such (for example)</div><div><br></div><div>alt=>elevation 1 99 Altitude in meters</div><div><br></div><div>elevation is the actual name of the variable in my netcdf file, and I map it to a new variable called "alt".</div><div><br></div><div>Try something like this for your variable:</div><div><br></div><div>temp=>temperature_at_ 1 99 Surface Temperature </div><div><br></div><div>Documentation is all in the GRADS user docs (<a href="http://grads.iges.org/grads/gadoc/gradcomdxdfopen.html">http://grads.iges.org/grads/gadoc/gradcomdxdfopen.html</a>)</div><div><br></div><div>DTYPE: </div><div><br></div><div><p class="plaintext">(<font color="#990000">GrADS
version 1.9</font>) For <a href="http://grads.iges.org/grads/gadoc/descriptorfile.html#DTYPE">DTYPE</a> netcdf or hdfsds or hdf5_grid (<font color="#990000">GrADS
version 2.0.a7+</font>) ,
the <em>units</em> field is a comma-delimited list of the varying
dimensions of the variable. Dimensions expressed as x, y, z, or
t correspond to the four axes defined by XDEF, YDEF, ZDEF and TDEF.
For example, a surface variable such as sea level pressure might
look like this:
</p><ul>
presSFC=>psfc 0 y,x Surface
Pressure
</ul><p>A time-varying atmospheric variable such as geopotential height
might look like this:</p>
<ul>
Height=>hght 17 t,z,y,x Geopotential
Height (m)
</ul><p class="plaintext">The order of the dimensions listed in the <em>units</em>
field does matter. They must describe the shape of the variable
as it was written to the SDF data file. For NetCDf files, this information
appears in the output from ncdump next to the variable name.
</p><p class="plaintext">If your data file contains a variable that also
varies in a non-world-coordinate dimension (e.g. histogram interval,
spectral band, ensemble number) then you can put a non-negative
integer in the list of varying dimensions that will become the array
index of the extra dimension. For example:
</p><ul><p class="plaintext"> VAR=>hist0 0 0,y,x
First historgram interval for VAR<br>
VAR=>hist1 0 1,y,x Second
historgram interval for VAR<br>
VAR=>hist2 0 2,y,x Third
histogram interval for VAR </p>
</ul><p class="plaintext">Another option in this example would be to fill
the unused Z axis with the histogram intervals: </p>
<ul><p class="plaintext"> zdef 3 linear 1 1<br>
... <br>
VAR=>hist 3 z,y,x VAR Histogram</p>
</ul><p class="plaintext">In this case, it would appear to GrADS that variable
'hist' varies in Z, but the user would have to remember that the
Z levels correspond to histogram intervals. The latter technique
makes it easier to slice through the data, but is not the most accurate
representation. And if you don't have an unsued world-coordinate
axis available, then you still have a way to access your data<em>.</em></p><div><br></div><div>Remember to use xdfopen when opening your CTL file and NOT sdfopen.</div><div><br></div><div>Cheers</div><div>Kevin</div><div><br></div></div><div><br></div><div><br></div><div><br><div><div>On Nov 18, 2009, at 11/18/09 - 6:21 AM, luis blacutt wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Thanks Kevin,<br><br>I changed the ctl file to:<br>
dset /home/lucho/Desktop/GlueNC/<a href="http://bolbia.pmg1jul.03236.rr8.reg.nc/">bolbia.pmg1jul.03236.rr8.reg.nc</a><br>
undef 9.999E+20<br>
title baseline 60-90<br>
*produced by LFA<br>
dtype netcdf<br>
options yrev<br>
ydef 82 linear -33.640000 0.439000<br>
xdef 97 linear -84.120000 0.440000<br>
tdef 1 linear 00Z01jul1961 1mo<br>
zdef 1 linear 1 1<br>
vars 1<br>
temperature_at_ 0 216,1,0 **<br>
ENDVARS<br>
<br>
now I got another error message<br><br>gancsetup error: Variable temperature_at_ not in netcdf file<br>Data Request Error: Error for variable 'temperature_at_'<br> Error ocurred at column 1<br>DISPLAY error: Invalid expression <br>
Expression = temperature_at_<br><br>Luis<br><br><div class="gmail_quote">On Tue, Nov 17, 2009 at 6:27 PM, Kevin M Levey <span dir="ltr"><<a href="mailto:klevey@customweather.com">klevey@customweather.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div style="">Luis,<div><br></div><div>the 5th argument is the data resolution, i.e. the incremental value, so if your x grid is 2 degrees, then your line should look like this</div>
<div><br></div><div><blockquote type="cite">xdef 97 linear -84.120000 2.00</blockquote></div><div><br></div><div><br></div><div>Your y increment is set to 2 degrees, so I am assuming your data resolution is 2x2 degrees.</div>
<div><br></div><div>Here is the documentation: </div><div><br></div><div><p><b>XDEF</b> <i>xnum mapping
<additional arguments></i> </p>
<a href="http://grads.iges.org/grads/gadoc/descriptorfile.html#TOP" target="_blank">back
to top</a><p> This entry defines the grid point values for the X dimension,
or longitude. The first argument, <i>xnum</i>, specifies the number of
grid points in the X direction. <i>xnum</i> must be an integer >= 1. <i>mapping</i>
defines the method by which longitudes are assigned to X grid points.
There are two options for <i>mapping</i>:
</p><ul>
LINEAR Linear mapping <br>
LEVELS Longitudes specified individually
</ul><p> The LINEAR mapping method requires two additional arguments: <i>start</i>
and <i>increment</i>. <i>start</i> is a floating point value that indicates
the longitude at grid point X=1. Negative values indicate western longitudes.
<i>increment</i> is the spacing between grid point values, given as a
positive floating point value.
</p><p> The LEVELS mapping method requires one additional argument, <i>value-list</i>,
which explicitly specifies the longitude value for each grid point. <i>value-list</i>
should contain <i>xnum</i> floating point values. It may continue into
the next record in the descriptor file, but note that records may not
have more than 255 characters. There must be at least 2 levels in <i>value-list</i>;
otherwise use the LINEAR method.
</p><p> Here are some examples:
</p><ul>
<table border="0" cellpadding="0" cellspacing="0" width="100%">
<tbody><tr>
<td width="6%">XDEF</td>
<td align="right" width="4%">144</td>
<td align="center" width="11%">LINEAR</td>
<td width="79%">0.0 2.5</td>
</tr>
<tr>
<td>XDEF</td>
<td align="right">72</td>
<td align="center">LINEAR</td>
<td>0.0 5.0 </td>
</tr>
<tr>
<td>XDEF</td>
<td align="right">12</td>
<td align="center"> LEVELS</td>
<td>0 30 60 90 120 150 180 210 240 270 300 330 </td>
</tr>
<tr>
<td>XDEF</td>
<td align="right">12</td>
<td align="center"> LEVELS</td>
<td>15 45 75 105 135 165 195 225 255 285 315 345</td></tr></tbody></table></ul><div><br></div></div><div><br></div><div><span style="font-size: 14px;">Regards,</span></div><div><div><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><div>
<div><div><div><div><br></div><div>Kevin M Levey, MSc in Oceans and Atmospheric Sciences (University of Cape Town)</div><div>Director of Meteorological Operations</div><div>CustomWeather, Inc.</div><div>San Francisco, California, USA</div>
<div><br></div><div>"Taking the World by Storm!"</div><div><br></div><div><a href="http://www.customweather.com/" target="_blank">http://www.customweather.com</a></div><div><a href="http://www.myforecast.com/" target="_blank">http://www.myforecast.com</a></div>
<div><a href="http://www.1stweather.com/" target="_blank">http://www.1stweather.com</a></div><div><br></div><div>cell: 415-794-0411</div><div>work: 415-777-3566</div><div>email: <a href="mailto:klevey@customweather.com" target="_blank">klevey@customweather.com</a></div>
</div></div></div></div></span>
</div><div><div></div><div class="h5">
<br><div><div>On Nov 17, 2009, at 11/17/09 - 2:07 PM, luis blacutt wrote:</div><br><blockquote type="cite">Dear Grads users<br>I'm doing my first ctl file, it will have two variables, so far I have the following commands:<br>
<br>dset /home/lucho/Desktop/GlueNC/bolbia.pag%x1%mc.%.nc<br>options template<br>undef 9.999E+20<br>
title baseline 60-90<br>*produced by LFA<br>dtype netcdf<br>options yrev<br>ydef 82 linear -33.640000 2.0000<br>xdef 97 linear -84.120000 -41.880000<br>tdef 1 linear 00Z01jul1961 1mo<br>zdef 1 linear 1 1<br>vars 2<br>total_precipita 0 216,1,0 **<br>
temperature_at_ 0 216,1,0 **<br>ENDVARS<br><br>When I try to run it, it gives me the following error message<br><br>Scanning description file: baseline.ctl<br>Open Error: Missing or invalid dimension increment value<br>
--> The invalid description file record is: <br> --> xdef 97 linear -84.120000 -41.880000<br> The data file was not opened. <br><br>MyI checked by creating a grib file and those are the right numbers, the domain is for Southamerica. What am I missing?<br>
Regards<br>Luis<br>
</blockquote></div><br></div></div></div></div></blockquote></div><br>
</blockquote></div><br></div></body></html>