unable to find variable in ncread

Hi,

Im having trouble finding variables in my nc file. First I use:

ncdisp('A20150802015171.L3b_SNSP_CHL.x.nc')

I get the display:

Source:
           C:\Users\WaterLab\Downloads\requested_files\A20150802015171.L3b_SNSP_CHL.x.nc
Format:
           netcdf4
Global Attributes:
           product_name                     = 'A20150802015171.L3b_SNSP_CHL.x.nc'
           title                            = 'MODIS Level-3 Binned Data'
           instrument                       = 'MODIS'
           platform                         = 'Aqua'
           temporal_range                   = '3-month'
           start_orbit_number               = 68499
           end_orbit_number                 = 69840
           date_created                     = '2020363234255000'
           processing_version               = 'unspecified'
           history                          = '/sdps/sdpsoper/Science/OCSSW/V2020.2/bin/l3bin ifile=A20150802015171.L3b_SNSP_CHL.nc ofile=A20150802015171.L3b_SNSP_CHL.x.nc latnorth=28.2000 latsouth=27.2000 lonwest=-176.2000 loneast=-175.6000'
           time_coverage_start              = '2015-03-21T00:05:00.000Z'
           time_coverage_end                = '2015-06-21T02:24:59.000Z'
           northernmost_latitude            = 28.1875
           southernmost_latitude            = 27.2292
           easternmost_longitude            = -175.5535
           westernmost_longitude            = -176.1989
           geospatial_lat_max               = 28.1875
           geospatial_lat_min               = 27.2292
           geospatial_lon_max               = -175.5535
           geospatial_lon_min               = -176.1989
           geospatial_lat_units             = 'degrees_north'
           geospatial_lon_units             = 'degrees_east'
           geospatial_lon_resolution        = 0.041667
           geospatial_lat_resolution        = 0.041667
           spatialResolution                = '4.6 km'
           data_bins                        = 318
           percent_data_bins                = 0.0013383
           units                            = 'chlor_a:mg m^-3,chl_ocx:mg m^-3'
           binning_scheme                   = 'Integerized Sinusoidal Grid'
           project                          = 'Ocean Biology Processing Group (NASA/GSFC/OBPG)'
           institution                      = 'NASA Goddard Space Flight Center, Ocean Ecology Laboratory, Ocean Biology Processing Group'
           standard_name_vocabulary         = 'CF Standard Name Table v36'
           Conventions                      = 'CF-1.6 ACDD-1.3'
           naming_authority                 = 'gov.nasa.gsfc.sci.oceandata'
           id                               = 'A20150802015171.L3b_SNSP_CHL.x.nc/L3/A20150802015171.L3b_SNSP_CHL.x.nc'
           license                          = 'https://science.nasa.gov/earth-science/earth-science-data/data-information-policy/'
           creator_name                     = 'NASA/GSFC/OBPG'
           publisher_name                   = 'NASA/GSFC/OBPG'
           creator_email                    = '[e-mail]'
           publisher_email                  = '[e-mail]'
           creator_url                      = 'https://oceandata.sci.gsfc.nasa.gov'
           publisher_url                    = 'https://oceandata.sci.gsfc.nasa.gov'
           processing_level                 = 'L3 Binned'
           cdm_data_type                    = 'point'
           identifier_product_doi_authority = 'https://dx.doi.org'
           identifier_product_doi           = '10.5067/AQUA/MODIS/L3B/CHL/2018'
           keywords_vocabulary              = 'NASA Global Change Master Directory (GCMD) Science Keywords'
           keywords                         = 'Earth Science > Oceans > Ocean Chemistry > Pigments > Chlorophyll; Earth Science > Oceans > Ocean Chemistry > Chlorophyllr'
Groups:
    /level-3_binned_data/
        Dimensions:
                   binListDim  = 318   (UNLIMITED)
                   binDataDim  = 318   (UNLIMITED)
                   binIndexDim = 4320  (UNLIMITED)
        Variables:
            BinList 
                   Size:       318x1
                   Dimensions: binListDim
                   Datatype:   UNSUPPORTED DATATYPE
            chlor_a 
                   Size:       318x1
                   Dimensions: binDataDim
                   Datatype:   UNSUPPORTED DATATYPE
            chl_ocx 
                   Size:       318x1
                   Dimensions: binDataDim
                   Datatype:   UNSUPPORTED DATATYPE
            BinIndex
                   Size:       4320x1
                   Dimensions: binIndexDim
                   Datatype:   UNSUPPORTED DATATYPE
    
    /processing_control/
        Attributes:
                   software_name    = 'L3BIN'
                   software_version = '5.13'
                   source           = 'A20150802015171.L3b_SNSP_CHL.nc'
                   l2_flag_names    = 'ATMFAIL,LAND,HILT,HISATZEN,STRAYLIGHT,CLDICE,COCCOLITH,LOWLW,CHLWARN,CHLFAIL,NAVWARN,MAXAERITER,ATMWARN,HISOLZEN,NAVFAIL,FILTER,HIGLINT'
        Groups:
            /processing_control/input_parameters/
                Attributes:
                           infile             = 'A20150802015171.L3b_SNSP_CHL.nc'
                           ofile              = 'A20150802015171.L3b_SNSP_CHL.x.nc'
                           pfile              = 'A20150802015171.L3b_SNSP_CHL.x.nc'
                           oformat            = 'netCDF4'
                           syear              = '9999'
                           eyear              = '9999'
                           sday               = '1970001'
                           eday               = '2038018'
                           sorbit             = '-1'
                           eorbit             = '-1'
                           out_parm           = ':DEFAULT:'
                           processing_version = 'unspecified'
                           reduce_fac         = '1'
                           merged             = ''
                           loneast            = '-175.600006'
                           lonwest            = '-176.199997'
                           latnorth           = '28.200001'
                           latsouth           = '27.200001'
                           verbose            = '0'
                           unit_wgt           = '0'
                           median             = '0'
                           deflate            = '5'
                           composite_prod     = ''
                           composite_scheme   = ''

I would like to open the variable chlor_a, so I type:

chla=ncread('A20150802015171.L3b_SNSP_CHL.x.nc','chlor_a')     

I receive the error:

Error using internal.matlab.imagesci.nc/getGroupAndVarid (line 2096)
Could not find variable or group 'chlor_a' in file.

Error in internal.matlab.imagesci.nc/read (line 593)
            [gid, varid] = getGroupAndVarid(this, location);

Error in ncread (line 66)
vardata = ncObj.read(varName, varargin{:});

I am also suprised there is not a lat and lon variable in here. Any suggestions? Thank you!

[Walter Roberson]

chla = ncread('A20150802015171.L3b_SNSP_CHL.x.nc', '/level-3_binned_data/chlor_a')

The groups are like directories

[akk]

Excellent! Thank you!

Answer 1

[Walter Roberson]

chla = ncread('A20150802015171.L3b_SNSP_CHL.x.nc', '/level-3_binned_data/chlor_a')

The groups are like directories