Re: how to extract data from a huge nc data file?

I am using Mac OS version 10.5.2 and processor is Dual 2 GHz PowerPC G5.
Memory is 2.5GB DDR SDRAM.
Is this a 32-bit OS? What's a 64-bit machine?
  Thanks,
 Tao

Xianglei Huang wrote:
> ncks is the right command for this type of job. It seems to me
> that most likely you are using a 32-bit OS so it cannot handle netcdf
> files beyond 4G (or 2G?). Try it on a 64-bit machine and it should work.
>
>
> Zhang Tao wrote:
>> Hi, all,
>>
>> I have a huge netcdf data file
>> "thetao_O1.20C3M_1.CCSM.ocnm.1950-01_cat_1999-12.nc" and
>> the size is about 12G.
>>
>> I want to extract parts of data and generate a small size netcdf
>> file, the specific command is listed in point 3 below
>> and I get the error message "segmentation fault" see point 2 below.
>> I can use "ncdump" to look at the attribution of the data, see
>> point 1 below.
>>
>> Does anyone know how to extract data from this huge nc file?
>>
>> Thanks,
>> Tao
>>
>>
>> 1)
>> netcdf thetao_O1.20C3M_1.CCSM.ocnm.1950-01_cat_1999-12 {
>> dimensions:
>> lon = 320 ;
>> lat = 395 ;
>> depth = 40 ;
>> bnds = 2 ;
>> time = UNLIMITED ; // (600 currently)
>> variables:
>> double lon_bnds(lon, bnds) ;
>> double lat_bnds(lat, bnds) ;
>> double depth_bnds(depth, bnds) ;
>> double time_bnds(time, bnds) ;
>> double lon(lon) ;
>> lon:axis = "X" ;
>> lon:standard_name = "longitude" ;
>> lon:bounds = "lon_bnds" ;
>> lon:long_name = "Longitude" ;
>> lon:units = "degrees_east" ;
>> double lat(lat) ;
>> lat:axis = "Y" ;
>> lat:standard_name = "latitude" ;
>> lat:bounds = "lat_bnds" ;
>> lat:long_name = "Latitude" ;
>> lat:units = "degrees_north" ;
>> double depth(depth) ;
>> depth:axis = "Z" ;
>> depth:standard_name = "depth" ;
>> depth:positive = "down" ;
>> depth:units = "m" ;
>> depth:bounds = "depth_bnds" ;
>> double time(time) ;
>> time:calendar = "noleap" ;
>> time:standard_name = "time" ;
>> time:axis = "T" ;
>> time:units = "days since 0000-1-1" ;
>> time:bounds = "time_bnds" ;
>> float thetao(time, depth, lat, lon) ;
>> thetao:comment = "Created using NCL code
>> CCSM_ocnm_2cf.ncl on\n",
>> " machine mineral" ;
>> thetao:missing_value = 1.e+20f ;
>> thetao:long_name = "sea_water_potential_temperature" ;
>> thetao:cell_methods = "time: mean (interval: 1 month)" ;
>> thetao:history = "Interpolated to regular grid from
>> dipole grid,\n",
>> "TEMP+273.15" ;
>> thetao:units = "K" ;
>> thetao:original_units = "C" ;
>> thetao:original_name = "TEMP" ;
>> thetao:standard_name =
>> "sea_water_potential_temperature" ;
>> thetao:_FillValue = 1.e+20f ;
>>
>> 2)
>> ---------------------------
>> /nas/tzhang/ZTIPCC4/ncar_ccsm3_0/20c3m/nc>
>> extract_thetao_20C3M_1.CCSM.csh &
>> [1] 41886
>> /nas/tzhang/ZTIPCC4/ncar_ccsm3_0/20c3m/nc> Segmentation fault
>>
>> [1] Exit 139 extract_thetao_20C3M_1.CCSM.csh
>> ----------------------------------------------------
>>
>> 3)
>> ncks -c -F -d depth,1,17 -v thetao
>> thetao_O1.20C3M_1.CCSM.ocnm.1950-01_cat_1999-12.nc
>> thetao_upper_O1.20C3M_1.CCSM.ocnm.1950-01_cat_1999-12.nc
>>
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>>
>>
>
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Received on Mon Jun 23 2008 - 13:02:49 MDT