<div dir="ltr">John, <br>thanks very much for your help, I decided to convert my NetCDF file to GRIB1 file<br>using `cdo -f grb copy ...` command...do you have any (...) about known problems with this<br>procedure?<br>Anyway I hope version 2.0 of MET will accept general format of NetCDF files.<br>
Thanks again, bye, Valerio<br><br><div class="gmail_quote">2008/9/23 John Halley Gotway <span dir="ltr"><<a href="mailto:johnhg@rap.ucar.edu">johnhg@rap.ucar.edu</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Valerio,<br>
<br>
I do think that it would be reasonable to massage your NetCDF files into a format that METv1.1 would read. However, METv1.1 is only compatible with a rather rigid format of NetCDF at this point. For<br>
the next release of MET, version 2.0, we're planning to support a more general format of NetCDF.<br>
<br>
Currently, MET expects gridded NetCDF data to abide by the following conventions:<br>
<br>
(1) dimensions named "lat" and "lon" define the dimension of the data.<br>
(2) variables have only two dimensions, "lat" and "lon".<br>
(3) variables are named using the GRIB code abbreviation for the GRIB field they represent and are in the units prescribed by that GRIB code. For example, a variable containing accumulated<br>
precipitation would be named "APCP" (GRIB code abbreviation) and its units would be millimeters.<br>
(4) several variable attributes are required to define the initialization, valid, and accumulation (if applicable) times.<br>
(5) global attributes defining the grid on which the data resides must be defined.<br>
<br>
The definition of the grid in (5) is necessary to perform conversions between lat/lon and grid x/y.<br>
<br>
I've attached a sample output file from PCP-Combine. This example contains data on a lat/lon grid - which I'm guessing is the projection your data is on. The attached file that ends in ".dump" is<br>
just a dump of the NetCDF header. In that file, please note the following:<br>
<br>
(1) The "lat" and "lon" dimensions are defined.<br>
(2) The variable named APCP contains accumulated precipitation in mm. The GRIB codes and corresponding abbreviations are defined here: <a href="http://www.nco.ncep.noaa.gov/pmb/docs/on388/table2.html" target="_blank">http://www.nco.ncep.noaa.gov/pmb/docs/on388/table2.html</a><br>
(3) The APCP variable contains the several attributes, but only the following are actually read by the code: level, init_time_ut, valid_time_ut, and accum_time (if not applicable, just set to 0).<br>
The "_ut" is for unixtime, or seconds since January 1, 1970.<br>
(4) Global attributes defining the projectsion:<br>
:Projection = "LatLon" ;<br>
:lat_ll_deg = "25.063000 degrees_north" ;<br>
:lon_ll_deg = "-124.938000 degrees_east" ;<br>
:delta_lat_deg = "0.125000 degrees" ;<br>
:delta_lon_deg = "0.125000 degrees" ;<br>
:Nlat = "224 grid_points" ;<br>
:Nlon = "464 grid_points" ;<br>
Here you'll just insert your grid definition info.<br>
<br>
Hope that helps, and feel free to write with more questions about this.<br>
<br>
John Halley-Gotway<br>
<a href="mailto:johnhg@ucar.edu">johnhg@ucar.edu</a><br>
<div><div></div><div class="Wj3C7c"><br>
<br>
capecchi wrote:<br>
> Dear met_help,<br>
> I'm currently involved in WRF verification issues for a biometeorological<br>
> service in Italy.<br>
> I'm interested in point-stat tools but I have, as input forecast data,<br>
> NetCDF files derived and post-elaborated from WRF GRIB1 output.<br>
> I read from MET User Guide that I'm supposed to provide as input data only<br>
> GRIB1 files or NetCDF format<br>
> that is output from the Pcp-Combine tool; I'm wondering if my NetCDF file<br>
> format are like the Pcp-Combine tool's format<br>
> (I'm attaching one as sample) or if you can suggest me some NetCDF to GRIB1<br>
> converter tools (like cdo, nco, or...)<br>
> Thanks in advance for any help you can give me, regards, Valerio Capecchi<br>
><br>
> **************************************************************************<br>
><br>
> Valerio Capecchi<br>
><br>
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<br>netcdf nam.20070330.ncep110 {<br>
dimensions:<br>
lat = 224 ;<br>
lon = 464 ;<br>
variables:<br>
float lat(lat, lon) ;<br>
lat:units = "degrees_north" ;<br>
lat:long_name = "Latitude" ;<br>
lat:_FillValue = -9999.f ;<br>
float lon(lat, lon) ;<br>
lon:units = "degrees_east" ;<br>
lon:long_name = "Longitude" ;<br>
lon:_FillValue = -9999.f ;<br>
float APCP(lat, lon) ;<br>
APCP:grib_code = 61 ;<br>
APCP:units = "kg/m^2" ;<br>
APCP:long_name = "Total precipitation" ;<br>
APCP:level = "SFC" ;<br>
APCP:_FillValue = -9999.f ;<br>
APCP:init_time = "20070330_000000" ;<br>
APCP:init_time_ut = 1175212800 ;<br>
APCP:valid_time = "20070331_120000" ;<br>
APCP:valid_time_ut = 1175342400 ;<br>
APCP:accum_time = "6 hours" ;<br>
<br>
// global attributes:<br>
:FileOrigins = "File /home/johnhg/<a href="http://nam.20070330.ncep110.nc" target="_blank">nam.20070330.ncep110.nc</a> generated 20080923_163157 UTC on host billiken by the PCP-Combine tool" ;<br>
:RunCommand = "Addition: /home/johnhg/nam.20070330.ncep110.grb with accumulation of 3 hours plus /home/johnhg/nam.20070330.ncep110.grb with accumulation of 3 hours." ;<br>
:Projection = "LatLon" ;<br>
:lat_ll_deg = "25.063000 degrees_north" ;<br>
:lon_ll_deg = "-124.938000 degrees_east" ;<br>
:delta_lat_deg = "0.125000 degrees" ;<br>
:delta_lon_deg = "0.125000 degrees" ;<br>
:Nlat = "224 grid_points" ;<br>
:Nlon = "464 grid_points" ;<br>
}<br>
<br></blockquote></div><br></div>