Re: MODIS HDF

Thanks Dennis. Using hdfeof helps a lot and gives me the lats/lons now.

Seems I am having another problem. After I read the hdfeos and retrieve
the lats/lons and data, I tried writing it to a file and always get segmentation fault.
What am I doing wrong?

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"
begin

; 1km annual npp modis on 1200x1200 tiles

a=addfile("/Users/notaro/downloads/Y2000/MOD17A3.A2000366.h11v11.305.2009342143541.hdf.hdfeos","r")

lat2d=a->GridLat_MOD_Grid_MOD17A3
lon2d=a->GridLon_MOD_Grid_MOD17A3

npp=short2flt(a->Npp_1km_MOD_Grid_MOD17A3)

npp!0="lat2d"
npp!1="lon2d"
npp@lat2d=lat2d
npp@lon2d=lon2d
npp@coordinates="lat2d lon2d"
npp@projection="sinusoidal"

printVarSummary(npp)

out=addfile("test.nc","c")
out->npp=npp
out->lat2d=lat2d
out->lon2d=lon2d

end

Variable: npp
Type: float
Total Size: 5760000 bytes
            1440000 values
Number of Dimensions: 2
Dimensions and sizes: [lat2d | 1200] x [lon2d | 1200]
Coordinates:
Number Of Attributes: 7
  lon2d : <ARRAY of 1440000 elements>
  lat2d : <ARRAY of 1440000 elements>
  _FillValue : 1e+20
  coordinates : lat2d lon2d
  hdfeos_name : Npp_1km
  projection : sinusoidal
  unsigned : True

On Aug 30, 2011, at 12:44 PM, Dennis Shea wrote:

> Mike
>
> [1]
> %> ncl_filedump MOD17A3.A2010365.h00v08.305.2011029145245.hdf
>
> yields
>
> Variable: f
> Type: file
> filename: MOD17A3.A2010365.h00v08.305.2011029145245
> path: MOD17A3.A2010365.h00v08.305.2011029145245.hdf
> file global attributes:
> HDFEOSVersion : HDFEOS_V2.16
> StructMetadata_0 : GROUP=SwathStructure
> END_GROUP=SwathStructure
> GROUP=GridStructure
> GROUP=GRID_1
> GridName="MOD_Grid_MOD17A3"
> XDim=1200
> YDim=1200
> UpperLeftPointMtrs=(-20015109.354000,1111950.519667)
> LowerRightMtrs=(-18903158.834333,0.000000)
> Projection=GCTP_SNSOID
> [SNIP]
>
> [2]
> If you append the '.hdfeos' suffix, you will get that lat/lon values.
>
> %> ncl_filedump MOD17A3.A2010365.h00v08.305.2011029145245.hdf.hdfeos
>
> Variable: f
> Type: file
> filename: MOD17A3.A2010365.h00v08.305.2011029145245.hdf
> path: MOD17A3.A2010365.h00v08.305.2011029145245.hdf
> file global attributes:
> dimensions:
> YDim_MOD_Grid_MOD17A3 = 1200
> XDim_MOD_Grid_MOD17A3 = 1200
> variables:
> double GridLat_MOD_Grid_MOD17A3 ( YDim_MOD_Grid_MOD17A3,
> XDim_MOD_Grid_MOD17A3 )
> projection : (null)
> corners : ( 9.995833332438675, 9.995833332438675,
> 0.004166666666293064, 0.004166666666293064 )
> long_name : latitude
> units : degrees_north
>
> double GridLon_MOD_Grid_MOD17A3 ( YDim_MOD_Grid_MOD17A3,
> XDim_MOD_Grid_MOD17A3 )
> projection : (null)
> corners : ( 177.2297839752788, -172.6245418649626,
> -170.00416710093, -179.9958337931229 )
> long_name : longitude
> units : degrees_east
> [snip]
>
> [3] Use the hdfeos suffix. The names are different than using 'just' hdf
> however NCL does provide the georeferenced data coordinates.
>
>
> [4] You might look at:
>
> http://www.ncl.ucar.edu/Applications/binning.shtml
>
> Good luck
> D
>
>
>
>
> On 8/30/11 11:23 AM, Michael Notaro wrote:
>> I am trying to work with MODIS HDF data of the land variable 1-km annual NPP (net primary productivity).
>>
>> ftp://ftp.ntsg.umt.edu/pub/MODIS/Mirror/MOD17_Science_2010/MOD17A3/
>>
>> Each file is on a separate tile. I put the info below on a sample file's
>> info on the variable Npp_1km and the 1200x1200 grid and bounding rectangle.
>>
>> It is my understanding that I should grab the rectangles that overlap my study region,
>> which is Wisconsin. I think 4 of them overlap it.
>>
>> I can read in the data with addfile (or use ncl_convert2nc). But I am not sure
>> how to retrieve the proper lats/lons to plot the data correctly. I used short2flt also
>> when reading it. I am guessing that the data grid must not be a normal rectangle but
>> stretched as the satellite moves, since the range of the lats is 10 degrees but the
>> range of the lons is 60 degrees.
>>
>> Any suggestions on how to plot this in NCL is appreciated.
>>
>> Michael
>>
>>
>> YDim_MOD_Grid_MOD17A3 = 1200 ;
>> XDim_MOD_Grid_MOD17A3 = 1200 ;
>>
>> short Npp_1km(YDim_MOD_Grid_MOD17A3, XDim_MOD_Grid_MOD17A3) ;
>> Npp_1km:hdf_name = "Npp_1km" ;
>> Npp_1km:units = "kg_C/m^2" ;
>> Npp_1km:long_name = "MOD17A3 NPP--MODIS Gridded 1KM Annual Net Primary Productivity (NPP)" ;
>> Npp_1km:_FillValue = -1s ;
>> Npp_1km:valid_range = 0s, -36s ;
>> Npp_1km:calibrated_nt = 23 ;
>> Npp_1km:add_offset_err = 0. ;
>> Npp_1km:add_offset = 0. ;
>> Npp_1km:scale_factor_err = 0. ;
>> Npp_1km:scale_factor = 0.0001 ;
>>
>> " OBJECT = NORTHBOUNDINGCOORDINATE\n",
>> " NUM_VAL = 1\n",
>> " VALUE = 69.9999999937138\n",
>> " END_OBJECT = NORTHBOUNDINGCOORDINATE\n",
>> "\n",
>> " OBJECT = SOUTHBOUNDINGCOORDINATE\n",
>> " NUM_VAL = 1\n",
>> " VALUE = 59.9999999946118\n",
>> " END_OBJECT = SOUTHBOUNDINGCOORDINATE\n",
>> "\n",
>> " OBJECT = EASTBOUNDINGCOORDINATE\n",
>> " NUM_VAL = 1\n",
>> " VALUE = -119.983333303015\n",
>> " END_OBJECT = EASTBOUNDINGCOORDINATE\n",
>> "\n",
>> " OBJECT = WESTBOUNDINGCOORDINATE\n",
>> " NUM_VAL = 1\n",
>> " VALUE = -179.999999938971\n",
>> " END_OBJECT = WESTBOUNDINGCOORDINATE\n",
>> "\n",
>>
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Received on Tue Aug 30 12:05:24 2011