Aqua_AIRS_Level2_AIRS2STC.005.cdl

// Purpose: CDL equivalent of the Level 2 OMI OMAERUV product files in
// HDF5-based HDF-EOS format archived in NASA GES DISC. The files shows how a
// Level 2 swath data file is usually encoded in the HDF-EOS convention and how
// they can be converted to a netCDF structure with CF convention.

// In this example, the original group structure is flattened. Variables are
// re-ordered into CF's coordinate and data variables. But minimal changes are
// made to the attribute names, so that readers can get an understanding of
// what information a L2 data product contains, particularly the coordinates,
// attributes, and metadata.
// A shorter, simplified, and CF-compliant version of this file is named:
//   "Short_Version_Aura_OMI_Level2_OMAERUV.003.cdl"

// This file can be converted to a nc4 file, but not a nc3 data file using
// ncgen because the ubyte and ushort variables are not supported by netCDF3:
// ncgen -k netCDF-4 -b Aura_OMI_Level2_OMAERUV.003.cdl

// Contact: Wenli Yang, GES DISC, wenli.yang@nasa.gov

netcdf {

 // Template source:
 // ftp://aurapar2u.ecs.nasa.gov/data/s4pa/Aura_OMI_Level2/OMAERUV.003/2015/001/OMI-Aura_L2-OMAERUV_2015m0101t0130-o55655_v003-2015m0107t202422.he5

 // File level (global) attributes.
 // All file level are originally in /HDFEOS/ADDITIONAL/FILE_ATTRIBUTES/ group,
 // except for the "HDFEOSVersion" attribute which is in the "/HDFEOS
 // INFORMATION/" group. In addition, the "/HDFEOS INFORMATION/" group also
 // contains three string variable each being metadata for the file. They are
 // the ArchiveMetadata, the CoreMetadata, and the StructMetadata, among which
 // the StructMetadata tells the variables dimensionality and dimension names.

 :HDFEOSVersion = "HDFEOS_5.1.11" ;
 :AuthorAffiliation = "NASA-GSFC" ;
 :AuthorName = "Omar Torres" ;
 :GranuleDay = 1 ;
 :GranuleMonth = 1 ;
 :GranuleYear = 2015 ;
 :InputVersions = "OMI-Aura_L1-OML1BRVG_2015m0101t0130-o55655_v003-2015m0101t072806.he4" ;
 :InstrumentName = "OMI" ;
 :OrbitData = "PREDICTED " ;
 :PGEVersion = "1.4.2" ;
 :ProcessLevel = "L2" ;
 :ProcessingCenter = "OMI SIPS" ;
 :ProcessingHost = "Linux omin1035 2.6.18-348.6.1.el5PAE i686" ;
 :TAI93At0zOfGranule = 694224008. ;

 // Swath attributes, originally in the "/HDFEOS/SWATHS/Aerosol NearUV Swath"
 // group. Because there is only one swath in this product, these attributes
 // can also be considered at global level. Some of the attributes can be used
 // to create the coordinate variables such as the altitude values.
 :EarthSundistance = 1.471011e+11f ;
 :NumTimes = 1644 ;
 :NumTimesSmallPixel = 0 ;
 :Altitude = 0.f, 1.5f, 3.f, 6.f, 10.f ;
 :SwathName = "OMI Aerosol Optical Depth and Single Scattering Albedo" ;
 :VerticalCoordinate = "Altitude" ;

 // Dimensions
 // Note: in HDF-EOS, the dimension names are stored in the structure metadata.
 // If one uses ncdump to dump a HDF-EOS file, the dimension names in its
 // structure will not be recognized by ncdump and the names will be shown as
 // phony_dim_0, phony_dim_1, etc.

 dimensions:
   nTimes = 1644 ; // number of time steps in a swath, the same as number of along track data points, "Track".
   nXtrack = 60 ;
   nLayers = 5 ; // number of height layers. In CF, it should be named "height"
   nWavel = 3 ;  // number of wavelengths. A more common name for this is "Band"


 variables:

 // Coordinate variables.
 // They are originally included in the "/HDFEOS/SWATHS/Aerosol NearUV
 // Swath/Geolocation Fields/" group. Notice that 1) two time values are
 // provided in this product, one UTC time and the other seconds in the day; 2)
 // the wavelength coordinate variable is not placed in the "geolocation
 // fields" but in the "data fields" because they are not "geo"; 3) the values
 // for the "nLayer" coordinate is not included in this product. It should be
 // provided to compliant with CF.

  float Latitude(nTimes, nXtrack) ;
     Latitude:_FillValue = -1.267651e+30f ;
     Latitude:MissingValue = -1.267651e+30f ;
     Latitude:Offset = 0. ;
     Latitude:ScaleFactor = 1. ;
     Latitude:Units = "deg" ;
     Latitude:Title = "Geodetic Latitude (deg)" ;
     Latitude:UniqueFieldDefinition = "Aura-Shared" ;

   float Longitude(nTimes, nXtrack) ;
     Longitude:_FillValue = -1.267651e+30f ;
     Longitude:MissingValue = -1.267651e+30f ;
     Longitude:Offset = 0. ;
     Longitude:ScaleFactor = 1. ;
     Longitude:Units = "deg" ;
     Longitude:Title = "Geodetic Longitude (deg)" ;
     Longitude:UniqueFieldDefinition = "Aura-Shared" ;

   double Time(nTimes) ;
     Time:_FillValue = -1.26765060022823e+30 ;
     Time:MissingValue = -1.26765060022823e+30 ;
     Time:Offset = 0. ;
     Time:ScaleFactor = 1. ;
     Time:Units = "s" ;
     Time:Title = "Time at Start of Scan (s, TAI93)" ;
     Time:UniqueFieldDefinition = "Aura-Shared" ;

  // this is an additional time value, in seconds in the day, which may not
  // needed in a CF netCDF
  float SecondsInDay(nTimes) ;
     SecondsInDay:Units = "s" ;
     SecondsInDay:_FillValue = -1.267651e+30f ;
     SecondsInDay:MissingValue = -1.267651e+30f ;
     SecondsInDay:Offset = 0. ;
     SecondsInDay:ScaleFactor = 1. ;
     SecondsInDay:Title = "Seconds of Day at Start of Scan" ;
     SecondsInDay:UniqueFieldDefinition = "Aura-Shared" ;

  // the wavelength variable is placed in the "Data fields"
   float Wavelength(nWavel) ;
     Wavelength:Units = "nm" ;
     Wavelength:_FillValue = -1.267651e+30f ;
     Wavelength:MissingValue = -1.267651e+30f ;
     Wavelength:Offset = 0. ;
     Wavelength:ScaleFactor = 1. ;
     Wavelength:Title = "Wavelength" ;
     Wavelength:UniqueFieldDefinition = "OMI-Specific" ;

  // An additional coordinate variable for height, float height(nLayers),
  // should be included to compliant with CF. The height values are presented
  // in the swath attribute as shown above and can be readily used for a height
  // coordinate variable, as the following:
   float height(nLayers);
     height:units = "km" ;
     height:long_name = "vertical distance above the surface" ;
     height:standard_name = "height" ;
     height:positive = "up";
     height:axis = "Z";


 // Data variables.
 // They are originally included in the "/HDFEOS/SWATHS/Aerosol NearUV
 // Swath/Data Fields/" group.

  float AIRSL3COvalue(nTimes, nXtrack) ;
     AIRSL3COvalue:_FillValue = -9999.f ;
     AIRSL3COvalue:MissingValue = -9999.f ;
     AIRSL3COvalue:Offset = 0. ;
     AIRSL3COvalue:ScaleFactor = 1. ;
     AIRSL3COvalue:Units = "NoUnits" ;
     AIRSL3COvalue:Title = "AIRS CO L3 data" ;
     AIRSL3COvalue:UniqueFieldDefinition = "OMI-Specific" ;

   float AerosolAbsOpticalDepthVsHeight(nTimes, nXtrack, nLayers, nWavel) ;
     AerosolAbsOpticalDepthVsHeight:_FillValue = -1.267651e+30f ;
     AerosolAbsOpticalDepthVsHeight:MissingValue = -1.267651e+30f ;
     AerosolAbsOpticalDepthVsHeight:Offset = 0. ;
     AerosolAbsOpticalDepthVsHeight:ScaleFactor = 1. ;
     AerosolAbsOpticalDepthVsHeight:Units = "NoUnits" ;
     AerosolAbsOpticalDepthVsHeight:Title = "Aerosol Absorption Optical Depth (tau_abs) at 5 levels" ;
     AerosolAbsOpticalDepthVsHeight:UniqueFieldDefinition = "OMI-Specific" ;

   float AerosolOpticalDepthVsHeight(nTimes, nXtrack, nLayers, nWavel) ;
     AerosolOpticalDepthVsHeight:_FillValue = -1.267651e+30f ;
     AerosolOpticalDepthVsHeight:MissingValue = -1.267651e+30f ;
     AerosolOpticalDepthVsHeight:Offset = 0. ;
     AerosolOpticalDepthVsHeight:ScaleFactor = 1. ;
     AerosolOpticalDepthVsHeight:Units = "NoUnits" ;
     AerosolOpticalDepthVsHeight:Title = "Aerosol Optical Depth (tau) at 5 levels" ;
     AerosolOpticalDepthVsHeight:UniqueFieldDefinition = "OMI-Specific" ;

   float AerosolSingleScattAlbVsHeight(nTimes, nXtrack, nLayers, nWavel) ;
     AerosolSingleScattAlbVsHeight:_FillValue = -1.267651e+30f ;
     AerosolSingleScattAlbVsHeight:MissingValue = -1.267651e+30f ;
     AerosolSingleScattAlbVsHeight:Offset = 0. ;
     AerosolSingleScattAlbVsHeight:ScaleFactor = 1. ;
     AerosolSingleScattAlbVsHeight:Units = "NoUnits" ;
     AerosolSingleScattAlbVsHeight:Title = "Aerosol Single Scattering Albedo (omega0) at 5 levels" ;
     AerosolSingleScattAlbVsHeight:UniqueFieldDefinition = "OMI-Specific" ;

   ubyte AerosolType(nTimes, nXtrack) ;
     AerosolType:_FillValue = 255UB ;
     AerosolType:MissingValue = 255UB ;
     AerosolType:Offset = 0. ;
     AerosolType:ScaleFactor = 1. ;
     AerosolType:Units = "NoUnits" ;
     AerosolType:Title = "Aerosol Type" ;
     AerosolType:UniqueFieldDefinition = "OMI-Specific" ;

   ushort AlgorithmFlagsVsHeight(nTimes, nXtrack, nLayers) ;
     AlgorithmFlagsVsHeight:_FillValue = 65535US ;
     AlgorithmFlagsVsHeight:MissingValue = 65535US ;
     AlgorithmFlagsVsHeight:Offset = 0. ;
     AlgorithmFlagsVsHeight:ScaleFactor = 1. ;
     AlgorithmFlagsVsHeight:Units = "NoUnits" ;
     AlgorithmFlagsVsHeight:Title = "Algorithm Flags Vs Height" ;
     AlgorithmFlagsVsHeight:UniqueFieldDefinition = "OMI-Specific" ;

   float FinalAerosolAbsOpticalDepth(nTimes, nXtrack, nWavel) ;
     FinalAerosolAbsOpticalDepth:_FillValue = -1.267651e+30f ;
     FinalAerosolAbsOpticalDepth:MissingValue = -1.267651e+30f ;
     FinalAerosolAbsOpticalDepth:Offset = 0. ;
     FinalAerosolAbsOpticalDepth:ScaleFactor = 1. ;
     FinalAerosolAbsOpticalDepth:Units = "NoUnits" ;
     FinalAerosolAbsOpticalDepth:Title = "Best Aerosol Absorption Optical Depth (tau_abs)" ;
     FinalAerosolAbsOpticalDepth:UniqueFieldDefinition = "OMI-Specific" ;

   float FinalAerosolLayerHeight(nTimes, nXtrack) ;
     FinalAerosolLayerHeight:_FillValue = -1.267651e+30f ;
     FinalAerosolLayerHeight:MissingValue = -1.267651e+30f ;
     FinalAerosolLayerHeight:Offset = 0. ;
     FinalAerosolLayerHeight:ScaleFactor = 1. ;
     FinalAerosolLayerHeight:Units = "km" ;
     FinalAerosolLayerHeight:Title = "Final Aerosol Layer Height (km)" ;
     FinalAerosolLayerHeight:UniqueFieldDefinition = "OMI-Specific" ;

   float FinalAerosolOpticalDepth(nTimes, nXtrack, nWavel) ;
     FinalAerosolOpticalDepth:_FillValue = -1.267651e+30f ;
     FinalAerosolOpticalDepth:MissingValue = -1.267651e+30f ;
     FinalAerosolOpticalDepth:Offset = 0. ;
     FinalAerosolOpticalDepth:ScaleFactor = 1. ;
     FinalAerosolOpticalDepth:Units = "NoUnits" ;
     FinalAerosolOpticalDepth:Title = "Best Aerosol Optical Depth (tau)" ;
     FinalAerosolOpticalDepth:UniqueFieldDefinition = "OMI-Specific" ;

   float FinalAerosolSingleScattAlb(nTimes, nXtrack, nWavel) ;
     FinalAerosolSingleScattAlb:_FillValue = -1.267651e+30f ;
     FinalAerosolSingleScattAlb:MissingValue = -1.267651e+30f ;
     FinalAerosolSingleScattAlb:Offset = 0. ;
     FinalAerosolSingleScattAlb:ScaleFactor = 1. ;
     FinalAerosolSingleScattAlb:Units = "NoUnits" ;
     FinalAerosolSingleScattAlb:Title = "Best Aerosol Single Scattering Albedo (omega0)" ;
     FinalAerosolSingleScattAlb:UniqueFieldDefinition = "OMI-Specific" ;

   ushort FinalAlgorithmFlags(nTimes, nXtrack) ;
     FinalAlgorithmFlags:_FillValue = 65535US ;
     FinalAlgorithmFlags:MissingValue = 65535US ;
     FinalAlgorithmFlags:Offset = 0. ;
     FinalAlgorithmFlags:ScaleFactor = 1. ;
     FinalAlgorithmFlags:Units = "NoUnits" ;
     FinalAlgorithmFlags:Title = "Final Algorithm Flags" ;
     FinalAlgorithmFlags:UniqueFieldDefinition = "OMI-Specific" ;

   float ImaRefractiveIndex(nTimes, nXtrack, nLayers, nWavel) ;
     ImaRefractiveIndex:_FillValue = -1.267651e+30f ;
     ImaRefractiveIndex:MissingValue = -1.267651e+30f ;
     ImaRefractiveIndex:Offset = 0. ;
     ImaRefractiveIndex:ScaleFactor = 1. ;
     ImaRefractiveIndex:Units = "NoUnits" ;
     ImaRefractiveIndex:Title = "Imaginary refractive Index" ;
     ImaRefractiveIndex:UniqueFieldDefinition = "OMI-Specific" ;

   ushort MeasurementQualityFlags(nTimes) ;
     MeasurementQualityFlags:_FillValue = 65535US ;
     MeasurementQualityFlags:MissingValue = 65535US ;
     MeasurementQualityFlags:Offset = 0. ;
     MeasurementQualityFlags:ScaleFactor = 1. ;
     MeasurementQualityFlags:Units = "NoUnits" ;
     MeasurementQualityFlags:Title = "Measurement Quality Flags" ;
     MeasurementQualityFlags:UniqueFieldDefinition = "OMI-Specific" ;

   float NormRadiance(nTimes, nXtrack, nWavel) ;
     NormRadiance:_FillValue = -1.267651e+30f ;
     NormRadiance:MissingValue = -1.267651e+30f ;
     NormRadiance:Offset = 0. ;
     NormRadiance:ScaleFactor = 1. ;
     NormRadiance:Units = "NoUnits" ;
     NormRadiance:Title = "Normalized Radiance" ;
     NormRadiance:UniqueFieldDefinition = "OMI-Specific" ;

   ushort PixelQualityFlags(nTimes, nXtrack, nWavel) ;
     PixelQualityFlags:_FillValue = 65535US ;
     PixelQualityFlags:MissingValue = 65535US ;
     PixelQualityFlags:Offset = 0. ;
     PixelQualityFlags:ScaleFactor = 1. ;
     PixelQualityFlags:Units = "NoUnits" ;
     PixelQualityFlags:Title = "Pixel Quality Flags" ;
     PixelQualityFlags:UniqueFieldDefinition = "OMI-Specific" ;

   float Reflectivity(nTimes, nXtrack, nWavel) ;
     Reflectivity:_FillValue = -1.267651e+30f ;
     Reflectivity:MissingValue = -1.267651e+30f ;
     Reflectivity:Offset = 0. ;
     Reflectivity:ScaleFactor = 1. ;
     Reflectivity:Units = "NoUnits" ;
     Reflectivity:Title = "Lambert Equivalent Reflectivity" ;
     Reflectivity:UniqueFieldDefinition = "OMI-Specific" ;

   float SurfaceAlbedo(nTimes, nXtrack, nWavel) ;
     SurfaceAlbedo:_FillValue = -1.267651e+30f ;
     SurfaceAlbedo:MissingValue = -1.267651e+30f ;
     SurfaceAlbedo:Offset = 0. ;
     SurfaceAlbedo:ScaleFactor = 1. ;
     SurfaceAlbedo:Units = "NoUnits" ;
     SurfaceAlbedo:Title = "Surface Albedo" ;
     SurfaceAlbedo:UniqueFieldDefinition = "OMI-Specific" ;

   float UVAerosolIndex(nTimes, nXtrack) ;
     UVAerosolIndex:_FillValue = -1.267651e+30f ;
     UVAerosolIndex:MissingValue = -1.267651e+30f ;
     UVAerosolIndex:Offset = 0. ;
     UVAerosolIndex:ScaleFactor = 1. ;
     UVAerosolIndex:Units = "NoUnits" ;
     UVAerosolIndex:Title = "UV Aerosol Index" ;
     UVAerosolIndex:UniqueFieldDefinition = "OMI-Specific" ;

  // Additional variables which are originally included in the swath's geolocation
  // fields but should be considered data variables in CF. Notice that in HDF-EOS,
  // solar and viewing geometry variables are traditionally placed in geolocation
  // fields (e.g., in MODIS L1B).
   float RelativeAzimuthAngle(nTimes, nXtrack) ;
     RelativeAzimuthAngle:_FillValue = -1.267651e+30f ;
     RelativeAzimuthAngle:MissingValue = -1.267651e+30f ;
     RelativeAzimuthAngle:Offset = 0. ;
     RelativeAzimuthAngle:ScaleFactor = 1. ;
     RelativeAzimuthAngle:Units = "deg(EastofNorth)" ;
     RelativeAzimuthAngle:Title = "Relative (sun + 180 - view) Azimuth Angle (deg)" ;
     RelativeAzimuthAngle:UniqueFieldDefinition = "OMI-Specific" ;

   float SolarZenithAngle(nTimes, nXtrack) ;
     SolarZenithAngle:_FillValue = -1.267651e+30f ;
     SolarZenithAngle:MissingValue = -1.267651e+30f ;
     SolarZenithAngle:Offset = 0. ;
     SolarZenithAngle:ScaleFactor = 1. ;
     SolarZenithAngle:Units = "deg" ;
     SolarZenithAngle:Title = "Solar Zenith Angle (deg)" ;
     SolarZenithAngle:UniqueFieldDefinition = "Aura-Shared" ;

   float ViewingZenithAngle(nTimes, nXtrack) ;
     ViewingZenithAngle:_FillValue = -1.267651e+30f ;
     ViewingZenithAngle:MissingValue = -1.267651e+30f ;
     ViewingZenithAngle:Offset = 0. ;
     ViewingZenithAngle:ScaleFactor = 1. ;
     ViewingZenithAngle:Units = "deg" ;
     ViewingZenithAngle:Title = "Viewing Zenith Angle (deg)" ;
     ViewingZenithAngle:UniqueFieldDefinition = "OMI-Specific" ;

   ushort GroundPixelQualityFlags(nTimes, nXtrack) ;
     GroundPixelQualityFlags:_FillValue = 65535US ;
     GroundPixelQualityFlags:MissingValue = 65535US ;
     GroundPixelQualityFlags:Offset = 0. ;
     GroundPixelQualityFlags:ScaleFactor = 1. ;
     GroundPixelQualityFlags:Units = "NoUnits" ;
     GroundPixelQualityFlags:Title = "Ground Pixel Quality Flags" ;
     GroundPixelQualityFlags:UniqueFieldDefinition = "OMI-Specific" ;

   ubyte XTrackQualityFlags(nTimes, nXtrack) ;
     XTrackQualityFlags:_FillValue = 255UB ;
     XTrackQualityFlags:MissingValue = 255UB ;
     XTrackQualityFlags:Offset = 0. ;
     XTrackQualityFlags:ScaleFactor = 1. ;
     XTrackQualityFlags:Units = "NoUnits" ;
     XTrackQualityFlags:Title = "XTrack Quality Flags" ;
     XTrackQualityFlags:UniqueFieldDefinition = "OMI-Specific" ;

   // the terrain pressure is actually a data variable. It contains the
   // the pressure value at the terrain surface. The variable is not
   // used as coordinate for any other variables.
   float TerrainPressure(nTimes, nXtrack) ;
     TerrainPressure:_FillValue = -1.267651e+30f ;
     TerrainPressure:MissingValue = -1.267651e+30f ;
     TerrainPressure:Offset = 0. ;
     TerrainPressure:ScaleFactor = 1. ;
     TerrainPressure:Units = "mbar" ;
     TerrainPressure:Title = "Terrain Pressure (mbar)" ;
     TerrainPressure:UniqueFieldDefinition = "Aura-Shared" ;

  // Data values are not included in this example
  data:

}