HDF-EOS V2 MODIS L2G-lite Land Surface Reflectance File Specification
Revision 1.0 (03/22/2007)

Product ID(s): MOD09 L2G 1DY 250M (MOD09GQ)

Description:

The MODIS 250m Resolution Level 2G (L2G) Land Surface Reflectance 
file contains the restructured Level 2 (L2) Land Surface Reflectance data 
(observations) which intersects a geographic area, a tile, in the MODIS Land 
global Level 3 (L3) grid.  The global L3 grid is divided into a number of 
tiles, areas with a nominal size of 1100 km by 1100 km (10 deg. by 10 deg.).  
The data is stored at a nominal grid resolution of 250m.

The 250m observations are stored in a nested hierarchy of grid cells 
with the four finer resolution 250m observations stored in the grid cell 
location corresponding to the coarser 500m resolution cells (stored in the 
corresponding MOD09GA file) containing data from the same orbit.  This product 
is meant to be used in conjunction with the 500m product because the important 
quality and viewing geometry information is stored in that product.

A single 250m surface reflectance observation consist of the surface 
reflectance for Bands 1 and 2, the corresponding Quality Assurance (QA) data, 
and the 250m observation coverage (obscov).  The observation coverage 
field gives a estimate of the intersection between the observation and the grid 
cell (relative to the observation area).

To relate to 500m observations that is stored in a seperate corresponding 500m 
L2G file (MOD09GA), there is a 250m scan value (q_scan) in MOD09GA that 
states whether the corresponding 250m observations from the same orbit are 
available for the 500m observation, and also states whether the 250m 
observations are from the same or a different scan.

There are also the orbit and granule pointer data that relates the overlapped
orbit and granule information to the corresponding metadata array given in the
archived metadata. 

The 500m observations (and corresponding 250m observations) are chosen in the 
following four steps:

1. First, one 500m observation in each orbit for each grid cell is selected by 
selecting the one with the largest observation coverage.

2. Next, for a 500m grid cell, the 500m observations with the maximum 
observation coverage for each orbit are selected and sorted in the order of 
ascending orbit numbers (earliest first).

3. For the 250m product, the first criteria is that the 250m observation has to 
be from the same orbit as the 500m observation in the same layer.  That is, the 
observation in the 500m grid cell observation always has the same orbit number 
as the four nested 250m observations (within the same layer).  Secondarily, if 
there are multiple 250m observations from the same orbit within a 250m grid 
cell, then the one with the maximum observation coverage is stored.  Note that 
this means that one or more of the nested 250m grid cells (even in the first 
layer) could be a fill value.  Also, the 250m grid observation could be from a 
different scan than the 500m observation.  In either of these special cases 
occurs, a bit in the "q_scan" SDS is set in the 500m product.

4. The first layer is then selected using the same compositing criteria as is 
used in the 8-day surface reflectance product (as of June 2005).  The 
observation with the highest score is pulled up to the first layer and stored.  
Note that the scoring does not use a maximum observation coverage criteria, it 
uses: 1) best observation based on a QA score; and 2) then for observations 
with the same QA score and that are close to the smallest observed blue value, 
the one with the lowest view zenith angle.

The observation coverage is stored with each observation so the end-user can 
always reorder the observations using whatever criteria they want, once they 
read them in.

This new format reduces the number of 250m L2G files from two files to 
one file per day for each tile.  The mapping between the original L2G files and 
this new L2G file is:

    MOD09GQK -- all SDSs except orb_cov
    MODPTQKM -- only obscov

There are two ways to which the observation data can be stored in a L2G
grid file, full and compact. The actual method is specified by the 
L2GStorageFormat metadata value. In both methods, the first layer of
observations is stored in a 2 dimensional array.  In the full method,
all of the values are stored in a 3 dimensional array with the slowest
varying dimension specifying the observation layer.  This is an inefficient
storage method because typically a large number of cells are empty.  For
the compact method, the additional observation values are stored in a single
dimensional array, with the dimension corresponding to the number of
additional observations since the beginning of the file.  Essentially, the
additional observations are run-length encoded with each observation stored
sequentially for each cell.

In addition, the a run-time parameter may specify that only the first layer 
be stored, in which case the additional arrays are not stored.

Points of Contact:
               Robert Wolfe
               NASA's Goddard Space Flight Center, Code 614.5
               Greenbelt, MD 20771
               (301) 614-5508
               robert.e.wolfe@nasa.gov

Principal Investigator:  
               Eric Vermote
               University of Maryland, College Park
               NASA's Goddard Space Flight Center, Code 614.5
               Greenbelt, MD 20771
               (301) 405-8052
               vermote@kratmos.gsfc.nasa.gov

===========================================================================

Generic Constructs

ECS Metadata Strings:

	Notes:	"FR" is an abbreviation for "FREE_RANGE".
		"D/T" is an abbreviation for "DATE/TIME"
		(A) implies that multiple values are stored within a
			single array.
		A value of "Variable" indicates that this value will vary
			according to the granule being processed.
		"M" means class M.
		
CoreMetadata.0

	This string will contain the following PVL fields:

                                              # of
 Field Name                          Data     Value  Value
                                     Type       s

 GROUP = INVENTORYMETADATA

   GROUP = CollectionDescriptionClass
      SHORTNAME                      STRING     1    "MOD09GQ"
      VERSIONID                      STRING     1    Variable
   END_GROUP = CollectionDescriptionClass

   GROUP = ECSDataGranule
      REPROCESSINGPLANNED            STRING     1    "further update
                                                      is anticipated"
      REPROCESSINGACTUAL             STRING     1    "reprocessed"
      LOCALGRANULEID                 STRING     1    Variable
      DAYNIGHTFLAG                   STRING     1    Variable
      PRODUCTIONDATETIME             D/T        1    Variable
      LOCALVERSIONID                 STRING     1    Variable
      SIZEMBECSDATAGRANULE	     DOUBLE	1    Variable
   END_GROUP = ECSDataGranule

   GROUP = PGEVersionClass
      PGEVERSION                     STRING     1    Variable
   END_GROUP = PGEVersionClass

   GROUP = InputGranule
      INPUTPOINTER                   STRING  FR (A)  Variable
   END_GROUP = InputGranule

   GROUP = RangeDateTime
      RANGEBEGINNINGDATE             DATE       1    Variable
      RANGEBEGINNINGTIME             TIME       1    Variable
      RANGEENDINGDATE                DATE       1    Variable
      RANGEENDINGTIME                TIME       1    Variable
   END_GROUP = RangeDateTime

   GROUP = GRing
      EXCLUSIONGRINGFLAG             STRING     1    "N"
   END_GROUP = GRing

   GROUP = GRingPoint
      GRINGPOINTLATITUDE             DOUBLE   4 (A)  Variable
      GRINGPOINTLONGITUDE            DOUBLE   4 (A)  Variable
      GRINGPOINTSEQUENCENO           INTEGER  4 (A)  Variable
   END_GROUP = GRingPoint

   GROUP = ZoneIdentifierClass
      ZONEIDENTIFIER                 STRING     1    "0"
   END_GROUP = ZoneIdentifierClass

   GROUP = OrbitCalculatedSpatialDomain

      ** number of containers is equal to "NumberofOrbits" **

      ORBITNUMBER                    INTEGER    1    Variable
      EQUATORCROSSINGLONGITUDE       DOUBLE     1    Variable
      EQUATORCROSSINGDATE            DATE       1    Variable
      EQUATORCROSSINGTIME            TIME       1    Variable
   END_GROUP = OrbitCalculatedSpatialDomain

   GROUP = MeasuredParameter

      PARAMETERNAME                  STRING  FR (A)  "MOD09G"

      GROUP = QAFLAGS
         AUTOMATICQUALITYFLAG        STRING     1    Variable
         AUTOMATICQUALITYFLAGEXPLANATION
                                     STRING     1    Variable
         SCIENCEQUALITYFLAG          STRING     1    Variable
         SCIENCEQUALITYFLAGEXPLANATION
                                     STRING     1    Variable
      END_GROUP = QAFlags

      GROUP = QAStats
         QAPERCENTMISSINGDATA        INTEGER    1    Variable
         QAPERCENTOUTOFBOUNDSDATA    INTEGER    1    Variable
         QAPERCENTINTERPOLATEDDATA   INTEGER    1    Variable
      END_GROUP = QAStats

   END_GROUP = MeasuredParameter

   GROUP = AssociatedPlatformInstrumentSensor
      ASSOCIATEDPLATFORMSHORTNAME    STRING     1    "Terra/Aqua"
      ASSOCIATEDINSTRUMENTSHORTNAME  STRING     1    "MODIS"
      ASSOCIATEDSENSORSHORTNAME      STRING     1    "MODIS"
   END_GROUP = AssociatedPlatformInstrumentSensor

   GROUP = AdditionalAttributes

      ADDITIONALATTRIBUTENAME        STRING  FR (A)  Variable
      PARAMETERVALUE                 STRING  FR (A)  Variable
	
      ADDITIONALATTRIBUTENAME.1  = "QAPERCENTGOODQUALITY"
      ADDITIONALATTRIBUTENAME.2  = "QAPERCENTOTHERQUALITY"
      ADDITIONALATTRIBUTENAME.3  = "QAPERCENTNOTPRODUCEDCLOUD"
      ADDITIONALATTRIBUTENAME.4  = "QAPERCENTNOTPRODUCEDOTHER"
      ADDITIONALATTRIBUTENAME.5  = "HORIZONTALTILENUMBER"
      ADDITIONALATTRIBUTENAME.6  = "VERTICALTILENUMBER"
      ADDITIONALATTRIBUTENAME.7  = "TileID"
      ADDITIONALATTRIBUTENAME.8  = "PROCESSVERSION"
      ADDITIONALATTRIBUTENAME.9  = "QAPERCENTPOOROUTPUT250MBAND1"
      ADDITIONALATTRIBUTENAME.10 = "QAPERCENTPOOROUTPUT250MBAND2"
      ADDITIONALATTRIBUTENAME.11 = "RESOLUTIONBANDS1AND2"
      ADDITIONALATTRIBUTENAME.12 = "identifier_product_doi"
      ADDITIONALATTRIBUTENAME.13 = "identifier_product_doi_authority"
      
   END_GROUP = AdditionalAttributes

 END_GROUP = INVENTORYMETADATA

ArchiveMetadata.0
	This string will contain the following PVL fields:

                                              # of
 Field Name                          Data     Value  Value
                                     Type       s
 GROUP = ARCHIVEMETADATA

   GROUP = BoundingRectangle
      WESTBOUNDINGCOORDINATE         DOUBLE     1    Variable
      NORTHBOUNDINGCOORDINATE        DOUBLE     1    Variable
      EASTBOUNDINGCOORDINATE         DOUBLE     1    Variable
      SOUTHBOUNDINGCOORDINATE        DOUBLE     1    Variable
   END_GROUP = BoundingRectangle

      GEOANYABNORMAL                 STRING     1    Variable
      GEOESTMAXRMSERROR              DOUBLE     1    Variable
      LONGNAME                       STRING     1    "MODIS/Terra Surface 
                              Reflectance Daily L2G Global 250m SIN Grid"
      SPSOPARAMETERS                 STRING     1    "2015"
      PROCESSINGCENTER               STRING     1    "MODAPS"
      NUMBEROFOVERLAPGRANULES        INTEGER    1    Variable
      NUMBEROFINPUTGRANULES          INTEGER    1    Variable
      NUMBEROFGRANULES               INTEGER    1    Variable
      GRANULENUMBERARRAY             INTEGER  FR(A)  Variable
      GRANULEPOINTERARRAY            INTEGER  FR(A)  Variable
      ORBITNUMBERARRAY               INTEGER  FR(A)  Variable
      NUMBEROFORBITS                 INTEGER    1    Variable
      GRANULEBEGINNINGDATETIME       STRING  "NumberofGranules"
                                                     Variable
      GRANULEENDINGDATETIME          STRING  "NumberofGranules"
                                                     Variable
      GRANULEDAYNIGHTFLAG            STRING  "NumberofGranules"
                                                     Variable
      GRANULEDAYOFYEAR               INTEGER  "NumberofGranules"
                                                     Variable
      GRANULEBEGINNINGDATETIMEARRAY  STRING    FR(A) Variable
      GRANULEENDINGDATETIMEARRAY     STRING    FR(A) Variable
      GRANULEDAYNIGHTFLAGARRAY       STRING    FR(A) Variable
      NADIRDATARESOLUTION            STRING      1   Variable
      CHARACTERISTICBINANGULARSIZE   DOUBLE      1   Variable
      CHARACTERISTICBINSIZE          DOUBLE      1   Variable
      DATACOLUMNS                    INTEGER     1   Variable
      DATAROWS                       INTEGER     1   Variable
      GLOBALGRIDCOLUMNS              INTEGER     1   Variable
      GLOBALGRIDROWS                 INTEGER     1   Variable
      MAXIMUMOBSERVATIONS            INTEGER     1   Variable
      ADDITIONALLAYERS               INTEGER     1   Variable
      TOTALOBSERVATIONS              INTEGER     1   Variable
      TOTALADDITIONALOBSERVATIONS    INTEGER     1   Variable
      COVERAGECALCULATIONMETHOD      STRING      1   Variable
      FIRSTLAYERSELECTIONCRITERIA    STRING      1   Variable
      L2GSTORAGEFORMAT               STRING      1   Variable
      QUALITYCLASSPERCENTAGE250MBAND1  INTEGER  16   Variable
      QUALITYCLASSPERCENTAGE250MBAND2  INTEGER  16   Variable
      PROCESSINGENVIRONMENT          STRING      1   Variable
      DESCRREVISION                  STRING      1   Variable
      SYSTEMFILENAME                 STRING  FR (A)  Variable
      PERCENTPROCESSED               INTEGER     1   Variable
      PERCENTLAND                    INTEGER     1   Variable
      PERCENTLANDSEAMASKCLASS        INTEGER     8   Variable
      PERCENTCLOUDY                  INTEGER     1   Variable
      PERCENTSHADOW                  INTEGER     1   Variable
      PERCENTLOWSUN                  INTEGER     1   Variable
      RANKING                        STRING      1   Variable
      KEEPALL                        STRING      1   Variable
      COVERAGEMINIMUM                DOUBLE      1   Variable
      MAXOUTPUTRES                   STRING      1   Variable
      DEEPOCEANFLAG                  STRING      1   Variable
      CLOUDOPTION                     STRING     1   Variable
      
      ******************************************************************
      *    1. The field "L2GStorageFormat" is either "full", "compact" 
      *       or "one layer only".
      *    2. The field "CoverageCalculationMethod" is either
      *       "area" or "volume".
      *    3. The field "FirstLayerSelectionCriteria" is either
      *       "nearest neighbor", "maximum observation coverage" or 
      *       "order of input pointer".
      ******************************************************************

END_GROUP = ARCHIVEMETADATA


StructuralMetadata.0
    This string will be populated automatically by HDF-EOS.

Grid Structure:  MODIS_Grid_2D

    Dimensions:

      Dimension Name                       Value

      YDim:MODIS_Grid_2D                   "DataRows"

      XDim:MODIS_Grid_2D                   "DataColumns"

    Corner Locations:

	Corner                Values

	UpperLeftPointMtrs    (Variable, Variable)

	LowerRightPointMtrs   (Variable, Variable)

    Geographic Grid Projection Parameters:

    Supported Grids:    Integerized Sinusoidal (GCTP_ISINUS)
                        Sinusoidal (GCTP_SNSOID)
            		Interrupted Goodes Homolosine (GCTP_GOOD)
            		Lambert Azimuthal Equal Area (GCTP_LAMAZ)

	Projection gridID = GCTP_ISINUS
		ProjParam[0]          6371007.181
		ProjParam[1 to 7]     0.0
		ProjParam[8]          86400
		ProjParam[9]          0.0
		ProjParam[10]         1.0
		ProjParam[11 to 12]   0.0
		Spherecode            -1
		GridOrigin            HDFE_GD_UL

	Projection gridID = GCTP_SNSOID
		ProjParam[0]          6371007.181
		ProjParam[1 to 12]    0.0
		Spherecode            -1
		GridOrigin            HDFE_GD_UL

	Projection gridID = GCTP_GOOD
		ProjParam[0 to 12]    0.0
		Spherecode            19
		GridOrigin            HDFE_GD_UL

	Projection gridID = GCTP_LAMAZ
		ProjParam[0]          6371228.0
		ProjParam[1 to 5]     0.0
		ProjParam[6]          Variable
		ProjParam[7 to 12]    0.0
		Spherecode            19
		GridOrigin            HDFE_GD_UL


Grid Structure:  MODIS_Grid_3D
    Dimensions:

      Dimension Name                       Value

      Additional Layers:MODIS_Grid_3D      "AdditionalLayers"
      YDim:MODIS_Grid_3D                   "DataRows"
      XDim:MODIS_Grid_3D                   "DataColumns"

   Corner Locations: (same as MODIS_Grid_2D)

   Geographic Grid Projection Parameters: (same as MODIS_Grid_2D)

===========================================================================

  Additional global attributes:

						Data
	Name					Type

	maximum_observations			INT8
	total_additional_observations		INT32
	l2g_storage_format			STRING
        NumberLandWater                         INT32
        identifier_product_doi                  STRING
        identifier_product_doi_authority        STRING
===========================================================================

  DataFields:

The following datafields are always in this file:

      num_observations
      sur_refl_b01_1
      sur_refl_b02_1
      QC_250m_1
      obscov_1
      iobs_res_1
      orbit_pnt_1
      granule_pnt_1
 
If the "L2GStorageFormat" metadata value is "full", the following
datafields are also present:

      sur_refl_b01_f
      sur_refl_b02_f
      QC_250m_f
      obscov_250m_f
      iobs_res_f
      orbit_pnt_f
      granule_pnt_f

If the "L2GStorageFormat" metadata value is "compact", the following
datafields are also present:

      sur_refl_b01_c
      sur_refl_b02_c
      QC_250m_c
      obscov_c
      iobs_res_c
      orbit_pnt_c
      granule_pnt_c
      nadd_obs_row

Each datafield has at least the following 4 attributes:

      long_name (STRING)
      units (STRING)
      valid_range (agrees with data type of SDS)
      _FillValue (agrees with data type of SDS)

Some datafields also contain the following 5 attributes:

      add_offset (float64)
      add_offset_err (float64)
      calibrated_nt (int32)
      scale_factor (float64)
      scale_factor_err (float64)
      Nadir Data Resolution (STRING -- "250m")
      QA index (STRING)

===========================================================================

	Name                    Data      Dimensions
	                        Type

        num_observations        INT8      "YDim:MODIS_Grid_2D",
	                                  "XDim:MODIS_Grid_2D"

	Description:

	The number of 250m observations per pixel contained within
	this L2G file.  In addition, if the value is less than zero,
	it means that intersections were not computed for this cell.
	If it is -1, it is part of the fill region of the grid.  If it
	is -2, it is in the area identified as 'non-production' in the
	Land Production Mask.

        HDF Attributes:

	             		  Number of
	               		  Values or
	               		    Max.
	Attribute        Data      String    Value
	                 Type      Length

	long_name        STRING      22      "Number of observations"
	units            STRING      4       "none"
	valid_range      INT8        2       0, 127
	_FillValue       INT8        1       -1

===========================================================================

	Name                    Data      Dimensions
	                        Type

	suf_refl_b01_1		INT16     "YDim:MODIS_Grid_2D",
	                                  "XDim:MODIS_Grid_2D"

	suf_refl_b01_f		INT16    "Additional Layers:MODIS_Grid_3D",
	                                  "YDim:MODIS_Grid_3D",
	                                  "XDim:MODIS_Grid_3D"

	suf_refl_b01_c		INT16     "TotalAdditionalObservations"
                                          metadata value

        Description:

	MODIS Land Surface Reflectance for Band 1.
	
	"suf_refl_b01_1" is for storing the first layer of observations
	and is always stored.
		
	"sur_refl_b01_f" and "sur_refl_b01_c" are for storing the
	additional layers of observations.  "suf_refl_b01_f" is for the
	full format and is stored only if "L2GStorageFormat" is "full".
	"suf_refl_b01_c" is for the compact format and is stored only if
	"L2GStorageFormat" is "compact".

        HDF Attributes:

	             		  Number of
	               		  Values or
	               		    Max.
	Attribute        Data      String    Value
	                 Type      Length

	long_name        STRING      60      Variable
	units            STRING      11      "reflectance"
	valid_range      INT16       2       -100, 16000
	_FillValue       INT16       1       -28672
	add_offset       FLOAT64     1       0.0
	add_offset_err   FLOAT64     1       0.0
	calibrated_nt    INT32       1       5
	scale_factor     FLOAT64     1       10000.0
	scale_factor_err FLOAT64     1       0.0
	Nadir Data Resolution
	                 STRING      4       "250m"
		
	Note: The attribute "long_name" is 
          "250m Surface Reflectance Band 1 - first layer" for "sur_refl_b01_1", 
	  "250m Surface Reflectance Band 1 - additional layers, full" 
             for "sur_refl_b01_f", or 
	  "250m Surface Reflectance Band 1 - additional layers, compact" 
	     for "sur_refl_b01_c".

===========================================================================

	Name                    Data      Dimensions
	                        Type

	suf_refl_b02_1		INT16     "YDim:MODIS_Grid_2D",
	                                  "XDim:MODIS_Grid_2D"

	suf_refl_b02_f		INT16    "Additional Layers:MODIS_Grid_3D",
	                                  "YDim:MODIS_Grid_3D",
	                                  "XDim:MODIS_Grid_3D"

	suf_refl_b02_c		INT16     "TotalAdditionalObservations"
                                          metadata value

        Description:

	MODIS Land Surface Reflectance for Band 2.
	
	"suf_refl_b02_1" is for storing the first layer of observations
	and is always stored.
		
	"sur_refl_b02_f" and "sur_refl_b02_c" are for storing the
	additional layers of observations.  "suf_refl_b02_f" is for the
	full format and is stored only if "L2GStorageFormat" is "full".
	"suf_refl_b02_c" is for the compact format and is stored only if
	"L2GStorageFormat" is "compact".

        HDF Attributes:

	             		  Number of
	               		  Values or
	               		    Max.
	Attribute        Data      String    Value
	                 Type      Length

	long_name        STRING      60      Variable
	units            STRING      11      "reflectance"
	valid_range      INT16       2       -100, 16000
	_FillValue       INT16       1       -28672
	add_offset       FLOAT64     1       0.0
	add_offset_err   FLOAT64     1       0.0
	calibrated_nt    INT32       1       5
	scale_factor     FLOAT64     1       10000.0
	scale_factor_err FLOAT64     1       0.0
	Nadir Data Resolution
	                 STRING      4       "250m"
		
	Note: The attribute "long_name" is 
          "250m Surface Reflectance Band 2 - first layer" for "sur_refl_b02_1", 
	  "250m Surface Reflectance Band 2 - additional layers, full" 
             for "sur_refl_b02_f", or 
	  "250m Surface Reflectance Band 2 - additional layers, compact" 
	     for "sur_refl_b02_c".

===========================================================================

	Name                    Data      Dimensions
	                        Type

	QC_250m_1		UINT16    "YDim:MODIS_Grid_2D",
	                                  "XDim:MODIS_Grid_2D"

	QC_250m_f		UINT16   "Additional Layers:MODIS_Grid_3D",
	                                  "YDim:MODIS_Grid_3D",
	                                  "XDim:MODIS_Grid_3D"

	QC_250m_c		UINT16   "TotalAdditionalObservations"
				          metadata value

        Description:
  
	MODIS Land Surface Reflectance 250m Quality Assurance.

	Note: Bits are listed from the MSB (bit 15) to the LSB (bit 0).

	Bit(s) Description
	14-15  spare (unused)
	13     adjacency correction performed; yes (1) or no (0)
	12     atmospheric correction performed; yes (1) or no (0)
	8-11   band 2 data quality, four bit range;
	         0000 ( 0) -- highest quality
                 1000 ( 8) -- dead detector; data interpolated in L1B
                 1001 ( 9) -- solar zenith >= 86 degrees
                 1010 (10) -- solar zenith >= 85 and < 86 degrees
                 1011 (11) -- missing input
                 1100 (12) -- internal constant used in place of climatological 
	                      data for at least one atmospheric constant
                 1101 (13) -- correction out of bounds, pixel constrained to
	                      extreme allowable value
                 1110 (14) -- L1B data faulty
                 1111 (15) -- not processed due to deep ocean or clouds
	4-7    band 1 data quality four bit range;
	       (SAME AS ABOVE)
        2-3    spare (unused)
	0-1    MODLAND QA bits; 
	       corrected product produced: 
	         00 -- ideal quality all bands,
	         01 -- less than ideal quality some or all bands;
	       corrected product not produced due to:
	         10 -- cloud effects all bands,
	         11 -- other reasons some or all bands may be fill value;
	       Note that a value of (11) overrides a value of (01)

	"QC_250m_1" is for storing the first layer of observations
	and is always stored.
		
	"QC_250m_f" and "QC_250m_c" are for storing the
	additional layers of observations.  "QC_250m_f" is for the
	full format and is stored only if "L2GStorageFormat" is "full".
	"QC_250m_c" is for the compact format and is stored only if 
	"L2GStorageFormat" is "compact".

         HDF Attributes:

	             		  Number of
	               		  Values or
	               		    Max.
	Attribute        Data      String    Value
	                 Type      Length

	long_name        STRING      59      Variable
	units            STRING      9       "bit field"
	valid_range      UINT16      2       0, 4096
	_FillValue       UINT16      1       2995
	Nadir Data Resolution
                         STRING      4       "250m"
	QA index         STRING    1800      Variable
		
	Note: The attribute "long_name" is 
	  "250m Reflectance Band Quality - first layer" for "QC_250m_1", 
	  "250m Reflectance Band Quality - additional layers, full" 
	     for "QC_250m_f", or
	  "250m Reflectance Band Quality - additional layers, compact" 
	     for "QC_250m_c".

==========================================================================

	Name                    Data      Dimensions
	                        Type

	obscov_1		INT8      "YDim:MODIS_Grid_2D",
	                                  "XDim:MODIS_Grid_2D"

	obscov_f		INT8     "Additional Layers:MODIS_Grid_3D",
	                                  "YDim:MODIS_Grid_3D",
	                                  "XDim:MODIS_Grid_3D"

	obscov_c		INT8      "TotalAdditionalObservations"
				          metadata value
        Description:
        
	Observation coverage is an estimate of the amount of intersection 
	between observation footprint and grid cell.
		
	"obscov_1" is for storing the first layer of observations
	and is always stored.
		
	"obscov_f" and "obscov_c" are for storing the
	additional layers of observations.  "obscov_f" is for the
	full format and is stored only if "L2GStorageFormat" is "full".
	"obscov_c" is for the compact format and is stored only if 
	"L2GStorageFormat" is "compact".
 
        HDF Attributes:

	             		  Number of
	               		  Values or
	               		    Max.
	Attribute        Data      String    Value
	                 Type      Length

 	long_name        STRING      49      Variable
	units            STRING      7       "percent"
	valid_range      INT8        2       0, 100
	_FillValue       INT8        1       -1
	add_offset       FLOAT64     1       0.0
	add_offset_err   FLOAT64     1       0.0
	calibrated_nt    INT32       1       5 
	scale_factor     FLOAT64     1       0.01 
	scale_factor_err  FLOAT64    1       0.0
		
	Note: The attribute "long_name" is 
	  "Observation coverage - first layer" for "obscov_1", 
	  "Observation coverage - additional layers, full" for "obscov_f", or
	  "Observation coverage - additional layers, compact" for "obscov_c".

===========================================================================

	Name                    Data      Dimensions
	                        Type

	orbit_pnt_1		INT8      "YDim:MODIS_Grid_2D",
	                                  "XDim:MODIS_Grid_2D"

	orbit_pnt_f		INT8      "Additional Layers:MODIS_Grid_3D",
	                                  "YDim:MODIS_Grid_3D",
	                                  "XDim:MODIS_Grid_3D"

	orbit_pnt_c		INT8      "TotalAdditionalObservations"
                                          metadata value


        Description:

	Pointer to the orbit information for each 250m observation.  This value 
        is zero relative, with zero (0) refering to the first orbit in the 
	"OrbitCalculatedSpatialDomain" HDF EOS inventory metadata group.

	"orbit_pnt_1" is for storing the first layer of observations
	and is always stored.
		
	"orbit_pnt_f" and "orbit_pnt_c" are for storing the
	additional layers of observations.  "orbit_pnt_f" is for the
	full format and is stored only if "L2GStorageFormat1km" is "full".
	"orbit_pnt_c" is for the compact format and is stored only if 
	"L2GStorageFormat1km" is "compact".

        HDF Attributes:

	             		  Number of
	               		  Values or
	               		    Max.
	Attribute        Data      String    Value
	                 Type      Length

	long_name        STRING      42      Variable
	units            STRING      6       "none"
	valid_range      INT8        2       0, 15
	_FillValue       INT8        1       -1
		
	Note: The attribute "long_name" is 
              "Orbit pointer - first layer" for "orbit_pnt_1", 
              "Orbit pointer - additional layers, full" for "orbit_pnt_f", or 
	      "Orbit pointer - additional layers, compact" for "orbit_pnt_c".

===========================================================================

	Name                    Data      Dimensions
	                        Type

	granule_pnt_1		UINT8     "YDim:MODIS_Grid_2D",
	                                  "XDim:MODIS_Grid_2D"

	granule_pnt_f		UINT8     "Additional Layers:MODIS_Grid_3D",
	                                  "YDim:MODIS_Grid_3D",
	                                  "XDim:MODIS_Grid_3D"

	granule_pnt_c		UINT8     "TotalAdditionalObservations"
                                          metadata value


        Description:

	Pointer to the granule information for each 250m observation.  This value 
        is zero relative, with zero (0) refering to the first overlap granule in the 
	"GranulePointerArray" HDF EOS ArchiveMetadata group.

	"granule_pnt_1" is for storing the first layer of observations
	and is always stored.
		
	"granule_pnt_f" and "granule_pnt_c" are for storing the
	additional layers of observations.  "orbit_pnt_f" is for the
	full format and is stored only if "L2GStorageFormat1km" is "full".
	"orbit_pnt_c" is for the compact format and is stored only if 
	"L2GStorageFormat1km" is "compact".

        HDF Attributes:

	             		  Number of
	               		  Values or
	               		    Max.
	Attribute        Data      String    Value
	                 Type      Length

	long_name        STRING      42      Variable
	units            STRING      6       "none"
	valid_range      UINT8        2       0, 254
	_FillValue       UINT8        1       255
		
	Note: The attribute "long_name" is 
              "Granule pointer - first layer" for "granule_pnt_1", 
              "Granule pointer - additional layers, full" for "granule_pnt_f", or 
	      "Granule pointer - additional layers, compact" for "granule_pnt_c".
===========================================================================

	Name                    Data      Dimensions
	                        Type

	nadd_obs_row		INT32	  "DataRows" metadata value

	Description:

	The number of additional observations in each row in the
	compact storage form of the L2G grid.

	This field is only stored if "L2GStorageFormat" is "compact".

        HDF Attributes:

	             		  Number of
	               		  Values or
	               		    Max.
	Attribute        Data      String    Value
	                 Type      Length

	long_name        STRING      41      "Number of additional observations 
					     per row"
	units            STRING      4       "none"
	valid_range      INT32       2       0, INT32_MAX
	_FillValue       INT32       1       -1

=========================================================================