[Met_help] [rt.rap.ucar.edu #87964] History for Opening IMERG and MRMS data in netcdf format (Problem)

[Julie Prestopnik via RT]

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  Initial Request
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Dear All,

First of all, thanks for the nice package that you have provided for free to academic community. I'm a new PhD student in UNSW and I'm trying to use MET package (MODE Tool) for doing some verification for IMERG data based on MRMS data. The problem is when I want to use MODE commands, it cant read my input files. The sample of both files are attached. I really appreciate if you could help me to find a way in order to open these files with MODE.

Regards,
Hooman


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  Complete Ticket History
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Subject: Opening IMERG and MRMS data in netcdf format (Problem)
From: Julie Prestopnik
Time: Tue Dec 04 11:43:02 2018

Hi Hooman.  Thank you for your interest the MODE tool.

I see that you're having trouble reading a NetCDF file in MET.  Thanks
for
sending sample data files. I took a look and see that it doesn't
*exactly*
follow any of the flavors of NetCDF supported by MET.  However, since
they're just on a regular lat/lon grid and is close enough the CF
convention, that'll do the trick.

The following a global attribute tells MET to interpret the data file
as
being CF-complaint:
   :conventions = "CF..."; (where ... is some version number)

Since your files lack that CF compliant value for the conventions
global
attribute, we need to explicitly tell MET how to handle it by setting
the "
file_type" config option to NETCDF_NCCF.

When I'm trying to figure out if MET can read gridded data, I usually
use
the plot_data_plane tool.

Here's a plot_data_plane command for plotting
"GaugeCorrQPE06H_0mabovemeansealevel" from the MRMS file:

plot_data_plane MRMSGC6H2018091406-regridded.nc
> MRMSGC6H2018091406-regridded.ps
> 'name="GaugeCorrQPE06H_0mabovemeansealevel"; level="(0,*,*)";
> file_type=NETCDF_NCCF;'


The plot_data_plane tool is now able to read this data:

DEBUG 1: Opening data file: MRMSGC6H2018091406-regridded.nc
> DEBUG 1: Creating postscript file: MRMSGC6H2018091406-regridded.ps


Here's a plot_data_plane command for plotting precipitationCal from
the
140600.nc file:

plot_data_plane 140600.nc 140600.ps 'name="precipitationCal";
> level="(*,*)"; file_type=NETCDF_NCCF;'


The plot_data_plane tool is able to read the data, however there is no
timing info in the file, so I get this warning message from
plot_data_plane:

DEBUG 1: Opening data file: 140600.nc
> WARNING:
> WARNING: NcCfFile::open() -> could not determine the valid time,
using 0.
> WARNING:
> DEBUG 1: Creating postscript file: 140600.ps


So MET isn't getting the timing info correct.  What can we do about
this? One option would be reformatting these NetCDF files into a
format
that MET can actually read... either CF-compliant NetCDF or the MET
NetCDF
format. However, that's pretty cumbersome.  Another option is for you
to
take advantage of a new feature in met-8.0, which is to write a Python
script to read data from these files, define the metadata, and then
pass
that to MET via memory.

On this page of our website, there are examples of running Python
scripts
to read data and pass it into MET:
https://dtcenter.org/met/users/downloads/analysis_scripts.php

The examples include reading ASCII, NetCDF, and binary input data.  7
of
the examples define data on a latlon grid and the 8th uses a lambert
conformal projection.  For each example, a plot_data_plane command is
listed where the command line arguments are links so that you can
download
the data, run the example yourself, and make sure you get the expected
output.

If the timing information doesn't matter for some reason, then you
could just
use the "file_type = NETCDF_NCCF;" option.  But if it does matter,
and presumably it does, then the Python route should work.

I hope that helps!

Julie

On Fri, Nov 30, 2018 at 6:58 AM Hooman Ayat via RT <met_help at ucar.edu>
wrote:

>
> Fri Nov 30 06:58:26 2018: Request 87964 was acted upon.
> Transaction: Ticket created by h.ayat at student.unsw.edu.au
>        Queue: met_help
>      Subject: Opening IMERG and MRMS data in netcdf format (Problem)
>        Owner: Nobody
>   Requestors: h.ayat at student.unsw.edu.au
>       Status: new
>  Ticket <URL:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=87964 >
>
>
> Dear All,
>
> First of all, thanks for the nice package that you have provided for
free
> to academic community. I'm a new PhD student in UNSW and I'm trying
to use
> MET package (MODE Tool) for doing some verification for IMERG data
based on
> MRMS data. The problem is when I want to use MODE commands, it cant
read my
> input files. The sample of both files are attached. I really
appreciate if
> you could help me to find a way in order to open these files with
MODE.
>
> Regards,
> Hooman
>
>

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