[GRASS-user] issues with netCDF import

[Damian Maddalena]

Hi Anna,

Thank you for the reply.

The output from running gdalinfo NETCDF:"global_30s_2009_153.nc 
<http://global_30s_2009_153.nc/>":lai is below. I do not see anything in 
the metadata that suggests a problem. Perhaps a more experienced eye can 
find the issue.

Thanks!!

-Damian

Warning 1: No UNIDATA NC_GLOBAL:Conventions attribute
Driver: netCDF/Network Common Data Format
Files: global_30s_2009_153.nc
Size is 43200, 21600
Coordinate System is `'
Origin = (-180.000000000000000,90.000000000000000)
Pixel Size = (0.008333333767951,-0.008333333767951)
Metadata:
   lai#long_name=leaf area index
   lai#scale_factor=0.1
   lai#units=m2/m2
   lat#long_name=coordinate latitude
   lat#units=degrees_north
   lon#long_name=coordinate longitude
   lon#units=degrees_east
   NC_GLOBAL#citation=Yuan, H., Dai, Y., Xiao, Z., Ji, D., Shangguan, 
W., 2011. Reprocessing the MODIS Leaf Area Index Products for Land 
Surface and Climate Modelling. Remote Sensing of Environment, 115(5), 
1171-1187. doi:10.1016/j.rse.2011.01.001
   NC_GLOBAL#creation_date=2011/09/27
   NC_GLOBAL#institution=Land-Atmosphere Interaction Research Group at 
Beijing Normal University (http://globalchange.bnu.edu.cn)
   NC_GLOBAL#title=LAI data sets for land surface and climate modelling
   NETCDF_DIM_EXTRA={time}
   NETCDF_DIM_time_DEF={1,4}
   NETCDF_DIM_time_VALUES=153
   time#long_name=day of year 2009
   time#units=day
Corner Coordinates:
Upper Left  (-180.0000000,  90.0000000)
Lower Left  (-180.0000000, -90.0000094)
Upper Right ( 180.0000188,  90.0000000)
Lower Right ( 180.0000188, -90.0000094)
Center      (   0.0000094,  -0.0000047)
Band 1 Block=43200x1 Type=Int16, ColorInterp=Undefined
   NoData Value=-32767
   Offset: 0,   Scale:0.100000001490116
   Metadata:
     long_name=leaf area index
     NETCDF_DIM_time=153
     NETCDF_VARNAME=lai
     scale_factor=0.1
     units=m2/m2


On 03/20/2014 11:12 PM, Anna Petrášová wrote:
> Hi Damian,
>
>
> On Wed, Mar 19, 2014 at 1:47 PM, Damian Maddalena 
> <damianmaddalena at gmail.com <mailto:damianmaddalena at gmail.com>> wrote:
>
>     I am having some difficulty with the import of a netCDF dataset
>     into GRASS 7. The dataset I am attempting to import is a 30 second
>     global LAI dataset that can be found here:
>     http://globalchange.bnu.edu.cn/research/lai/
>
>     I have successfully imported other netCDF files into this build
>     (worldCLIM and the soils data from the same source as this LAI
>     data, for example), but this particular data is giving me issues.
>     I have tried several files from several of the years available of
>     the global LAI product. I get the same results.
>
>     I am running the following commands in a global lat/lon location:
>
>     g.region n=90 s=-90 e=-180 w=180 res=0.008333333767951  (I have
>     also tried res=00:00:30.)
>
>
> r.in.gdal does not respect region
>
>     r.in.gdal input=NETCDF:"global_30s_2009_153.nc
>     <http://global_30s_2009_153.nc>":lai output=testNETCDF -o
>
>     The file imports with some warnings.
>
>     Warning 1: No UNIDATA NC_GLOBAL:Conventions attribute
>     WARNING: Over-riding projection check
>     WARNING: Fixing subtle input data rounding error of south boundary
>              (-9.38773e-06>4.62963e-08)
>
>     It appears to be null when plotted, though r.info <http://r.info>
>     reports min of 0 and max of 70. r.info <http://r.info> hints at an
>     issue with the e-w resolution:
>
>      |            N:        90N    S:        90S   Res: 0:00:30
>      |            E: 179:59:59.932408W    W:       180W   Res:
>     0:00:00.000002
>
>     r.stats seems to indicate that all data is null?
>
>     r.stats testNETCDF -cp
>     100%
>     * 900072000 100.00%
>
>     d.histogram plots nothing.
>
>     Any hints would be greatly appreciated.
>
>
> I wanted to try it myself, but it's too big to download it now. Could 
> you post output of:
>
> gdalinfo NETCDF:"global_30s_2009_153.nc 
> <http://global_30s_2009_153.nc/>":lai
>
> I am not an expert on netcdf but others might have some idea based on 
> the gdalinfo output.
>
> Regards,
>
> Anna
>
>
>     Thanks!!
>
>     -Damian
>
>
>
>
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>

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