/
swath_omi_l2.cdl
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swath_omi_l2.cdl
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// -*-C++-*-
// 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 simplified, CF-compliant example will later be
// derived from this file.
// 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 pressure layers. In CF, it should be named "pressure"
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" ;
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" ;
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" ;
// 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" ;
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" ;
// 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" ;
// Data are not included in this example
data:
}