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[IDV #LPW-471935]: Plotting .hdf files in IDV

Hi Alexa,

It is a little tricky but you can fix these problems with a bit of
NcML. To get us going, let's look at the following NcML which can be
read into the IDV and will allow you to view the
`channel_14_brightness_temperature' over time. This file should be
located next to your `hdf' files. Please read the comments in the NcML
for more information about what is going on here.

,----
| <?xml version="1.0" encoding="UTF-8"?>
| <netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
|   <!-- Create a time coordinate variable that will be used for the 
aggregation. -->
|   <variable name="time" type="int" shape="time" >
|     <!-- Let's add some units. Alexa: please make sure these units are 
correct. -->
|     <attribute name="units" value="minutes since 2014-04-04 19:09"/>
|     <!-- Specify this variable as a time coordinate -->
|     <attribute name="_CoordinateAxisType" value="Time" />
|     <!-- Increment each file listed below by 10 minutes. Alexa, please make 
sure this -->
|     <!-- assumption about the times is correct. -->
|     <values start="0" increment="10" />
|   </variable>
|   <!--   Specify the coordinates of time lat lon for this one variable. 
Please use -->
|   <!-- this as an example for other variables you are interersted in. In 
other -->
|   <!-- words, you can copy and paste this variable NcML element for your 
other -->
|   <!-- variables. -->
|   <variable name="channel_14_brightness_temperature" shape="lines elements" 
type="short">
|     <attribute name="coordinates" value="time pixel_latitude pixel_longitude" 
/>
|   </variable>
|   <!-- Now you are ready to do your aggregation, which is the easy part at 
this point -->
|   <aggregation dimName="time" type="joinNew">
|     <variableAgg name="T"/>
|     <netcdf location="geocatL1.MTSAT-1R.2014044.190900.hdf"/>
|     <netcdf location="geocatL1.MTSAT-1R.2014044.191900.hdf"/>
|   </aggregation>
| </netcdf>
`----

In summary, this NcML should aggregate over time the two of HDF files
you provided. You will see only one variable that is aggregated over
time; `channel_14_brightness_temperature'.  I'll leave it up to you to
do the others though do not hesitate to ask for help.

Also, if interested, there are also fancier tricks we can do here such
as NcML can be smart enough to extract the times from the file names.

Best,

Unidata IDV Support

> Ok sounds promising. Here is the link to another file, which should differ 
> only in time — 
> https://drive.google.com/file/d/0B1jVlP9ZfAZCRDVyczU3N2NMbFU/view?usp=sharing 
>   -Alexa
> 
> > On Mar 30, 2016, at 4:49 PM, Unidata IDV Support <address@hidden> wrote:
> >
> > Alexa,
> >
> > Indeed we may be able to patch things up with a bit of ncml. I only found 
> > one
> > file at the drive.google location. Would it be possible to see more so that 
> > we
> > have something to aggregate?
> >
> > Best,
> >
> > Unidata IDV Support
> >
> >> Hello IDV Support,
> >>
> >> I am working on reading in a number of HDF files using ‘aggregate grids by 
> >> time’ or similar. I am able to read the files in individually without a 
> >> problem, but it looks like the time variable is not recognized. The error 
> >> message is "Grid data source failed making data set….Dimension time does 
> >> not exist”. Any ideas for how to specify the time variable? Could this be 
> >> achieved with an .ncml script?
> >>
> >> Example file is located here: 
> >> https://drive.google.com/file/d/0B1jVlP9ZfAZCRFhkRVM2aVVRVGc/view?usp=sharing
> >>
> >> All the best
> >>
> >> Alexa
> >>
> >
> >
> > Ticket Details
> > ===================
> > Ticket ID: LPW-471935
> > Department: Support IDV
> > Priority: Normal
> > Status: Closed
> >
> 
> 


Ticket Details
===================
Ticket ID: LPW-471935
Department: Support IDV
Priority: Normal
Status: Closed