VNP10 Product File Specification

Version:	V1.0.0
Revision:	0
Date:		22 January 2019
ESDT:		VNP10
Product name:	Snow Cover
Product Level:	2
PGE:		507

Point of Contact:	George Riggs
			SSAI
			NASA, GSFC, Code 971
			Greenbelt, MD 20771
			301-614-5650
			George.A.Riggs.1@gsfc.nasa.gov

Principal Investigator: Dorothy K. Hall
			NASA, GSFC, Code 971
			Greenbelt, MD 20771
			301-614-5771
			Dorothy.K.Hall@nasa.gov

Co-Investigator: 	George Riggs
			SSAI
			NASA, GSFC, Code 971
			Greenbelt, MD 20771
			301-614-5650
			George.A.Riggs.1@gsfc.nasa.gov
			

Description:
This data set reports the location of snow cover using radiance data acquired by the Visible Infrared Imager Radiometer Suite 
(VIIRS) on board the Suomi National Polar-orbiting Partnership (NPP) satellite. Snow cover is identified using the Normalized 
Difference Snow Index (NDSI) and a series of quality control screens.

Snow covered land typically has a very high reflectance in visible bands and very low reflectance in the shortwave infrared. 
The Normalized Difference Snow Index (NDSI) reveals the magnitude of this difference, with values greater than 0 typically 
indicating the presence of at least some snow. The algorithm for this data set calculates NDSI using VIIRS image bands I1 
(0.64 Ám, visible red) and I3 (1.61 Ám, shortwave near-infrared) and then applies a series of data screens designed to alleviate 
likely errors and flag uncertain snow detections.

The data product and algorithm are described in the VIIRS Snow Cover Data Product User Guide. The user should refer to that 
document for detailed description of the product, how to interpret the product and attributes (metadata).  Other information 
may be found at https://nsidc.org/data/VNP10

SDSs produced:
     Algorithm_bit_flags_QA
     Basic_QA
     NDSI
     NDSI_Snow_Cover
     latitude
     longitude

Contents:
Global Metadata:

Name:			Type:	Num_Val:	Source:	Value:

AlgorithmType		STRING	1		STIG	"OPS"
AlgorithmVersion	STRING	1		STIG	Variable
Conventions		STRING	1		STIG	Variable
DayNightFlag		STRING	1		STIG	"Day"
EastBoundingCoord	FLOAT	1		STIG	Variable
WestBoundingCoord 	FLOAT	1		STIG	Variable
NorthBoundingCoord 	FLOAT	1		STIG	Variable
SouthBoundingCoord	FLOAT	1		STIG	Variable
GRingPointLongitude	DOUBLE	4		PGE	Variable
GRingPointLatitude	DOUBLE	4		PGE	Variable
RangeEndingDate		STRING	1		PGE	Variable
RangeEndingTime		STRING	1		PGE	Variable
RangeBeginningDate	STRING	1		PGE	Variable
RangeBeginningTime	STRING	1		PGE	Variable
StartTime		STRING	1		PGE	Variable
EndTime			STRING	1		PGE	Variable	
InputPointer		STRING	3		PGE	Variable
InstrumentShortname	STRING	1		PGE	"VIIRS"
LocalGranuleID		STRING	1		PGE	Variable
LongName		STRING	1		STIG	"VIIRS/NPP Snow Cover 6-Min L2 Swath 375m"
PGEVersion		STRING	1		PGE	Variable
PGE_EndTime		STRING	1		PGE	Variable
PGE_Name		STRING	1		PGE	"PGE507"
PGE_StartTime		STRING	1		PGE	Variable
ProcessCenter		STRING	1		STIG	"LandSIPS"
ProcessingEnvironment	STRING	1		PGE	Variable
QAPercentBestQuality	STRING	1		PGE	Variable
QAPercentCloudCover	STRING	1		PGE	Variable
QAPercentGoodQuality	STRING	1		PGE	Variable
QAPercentOtherQuality	STRING	1		PGE	Variable
QAPercentPoorQuality	STRING	1		PGE	Variable
SatelliteInstrument	STRING	1		PGE	"NPP_OPS"
ShortName		STRING	1		MCF	"VNP10"
VersionID		STRING	1		PGE	Variable
cdm_data_type		STRING	1		PGE	"swath"
creator_email		STRING	1		PGE	"modis-ops@lists.nasa.gov"
creator_name		STRING	1		PGE	"VIIRS Land SIPS Processing Group"
creator_url		STRING	1		PGE	"http://ladsweb.nascom.nasa.gov"
identifier_product_doi	STRING	1		PGE	"10.5067/VIIRS/VNP10.001"
identifier_product_doi_authority
			STRING	1		PGE	"http://dx.doi.org"
institution		STRING	1		PGE	"NASA Goddard Space Flight Center"
keywords_vocabulary	STRING	1		PGE	"NASA Global Change Master Directory (GCMD) Science Keywords"
license			STRING	1		PGE	"http://science.nasa.gov/earth-science/earth-science-data/data-information-policy/"
naming_authority	STRING	1		PGE	"gov.nasa.gsfc.VIIRSland"
processing_level	STRING	1		PGE	"Level 2"
project			STRING	1		PGE	"VIIRS Land SIPS Snow Cover Project"
publisher_email		STRING	1		PGE	"modis-ops@lists.nasa.gov"
publisher_name		STRING	1		PGE	"LAADS"
publisher_url		STRING	1		PGE	"http://ladsweb.nascom.nasa.gov"
stdname_vocabulary	STRING	1		PGE	"NetCDF Climate and Forecast (CF) Metadata Convention"
title			STRING	1		STIG	"VIIRS Snow Cover Data"

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

SDS Name:	latitude
Description:	Latitude data
Number Type:	DFNT_FLOAT32
Rank:		2
Dimension sizes:(6496,6400)
Dimension Names:
	Dimension0:	"number_of_lines"
	Dimension1:	"number_of_pixels"

SDS Attributes: 
Name:			Type:		Num_val:	Source:	Value:
long_name		STRING		1		PGE	"Latitude data"
units			STRING		1		PGE	"degrees_north"
valid_range		DFNT_FLOAT32	2		PGE	-90.00000, 90.0000
_FillValue		DFNT_FLOAT32	1		PGE	-999.0000

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

SDS Name:	longitude
Description:	Longitude data
Number Type:	DFNT_FLOAT32
Rank:		2
Dimension sizes:(6496,6400)
Dimension Names:
	Dimension0:	"number_of_lines"
	Dimension1:	"number_of_pixels"

SDS Attributes: 
Name:			Type:		Num_val:	Source:	Value:
long_name		STRING		1		PGE	"Longitude data"
units			STRING		1		PGE	"degrees_east"
valid_range		DFNT_FLOAT32	2		PGE	-180.00000, 180.0000
_FillValue		DFNT_FLOAT32	1		PGE	-999.0000

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

SDS Name:	NDSI_Snow_Cover

Description:	Snow cover by NDSI
Number Type:	DFNT_UINT8
Rank:		2
Dimension sizes:(6496,6400)
Dimension Names:
	Dimension0:	"number_of_lines"
	Dimension1:	"number_of_pixels"

SDS Attributes:
Name:			Type:		Num_val:	Source:	Value:
long_name		STRING		string length	PGE	"Snow cover by NDSI"
valid_range		DFNT_UINT8	2		PGE	0,100
_FillValue		DFNT_UNIT8	1		PGE	255
coordinates		STRING		1		PGE	"latitude longitude"
mask_meanings		STRING		1		PGE	"201=no decision, 211=night, 237=lake, 239=ocean, 250=cloud, 251=missing data, 253=bowtie trim, 254=L1B fill"
mask_values		DFNT_UINT8	9		PGE	201, 211, 237, 239, 250, 251, 253, 254

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

SDS Name:	NDSI

Description:	NDSI for land/inland water pixels
Number Type:	DFNT_FLOAT32
Rank:		2
Dimension sizes:(6496,6400)
Dimension Names:
	Dimension0:	"number_of_lines"
	Dimension1:	"number_of_pixels"

SDS Attributes:
Name:			Type:		Num_val:	Source:	Value:
long_name		STRING		string length	PGE	"NDSI for land/inland water pixels"
valid_range		DFNT_UINT8	2		PGE	-1000,1000
scale_factor		DFNT_FLOAT32	1		PGE	0.001
_FillValue		DFNT_INT16	1		PGE	32767
coordinates		STRING		1		PGE	"latitude longitude"
mask_meanings		STRING		1		PGE	"21100=night, 23900=ocean, 25100=L1B_missing, 25200=L1B_unusable, 25300=bowtie_trim, 25400=L1B_fill"
mask_values		DFNT_UINT8	9		PGE	21100, 23900, 25100, 25200, 25300, 25400

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

SDS Name:	Algorithm_bit_flags_QA
Description:	Algorithm bit flags
Number Type:	DFNT_UINT8
Rank:		2
Dimension sizes:(6496,6400)
Dimension Names:
	Dimension0:	"number_of_lines"
	Dimension1:	"number_of_pixels"

SDS Attributes:
Name:			Type:		Num_val:	Source:	Value:
long_name		STRING		string length	PGE	"Algorithm bit flags"
comment			STRING		string length	PGE	"Bit flags are set for select conditions detected by data screens in the algorithm, multiple flags may be set for a pixel.Default is all bits off"
valid_range		DFNT_UING8	2		PGE	0,255
coordinates		STRING		1		PGE	"latitude longitude"
flag_masks		STRING		1		PGE	"1b, 2b, 4b, 8b, 16b, 32b, 64b, 128b"
flag_meanings		STRING		1		PGE	"inland_water_flag low_visible_screen low_NDSI_screen combined_surface_temperature_and_height_screen/flag spare high_SWIR_screen/flag spare solar_zenith_flag"

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

SDS Name:	Basic_QA

Description:	Basic QA value
Number Type:	DFNT_UINT8
Rank:		2
Dimension sizes:(6496,6400)
Dimension Names:
	Dimension0:	"number_of_lines"
	Dimension1:	"number_of_pixels"

SDS Attributes:
Name:			Type:		Num_val:	Source:	Value:
long_name		STRING		string length	PGE	"Basic QA value"
_FillValue		DFNT_UNIT8	1		PGE	255
coordinates		STRING		1		PGE	"latitude longitude"
key			STRING		1		PGE	"0=good, 1=poor, 2=bad, 3=other"
mask_meanings		STRING		1		PGE	"211=night 239=ocean 250=cloud 252=no_decision 253=bowtie_trim"
mask_values		DFNT_UINT8	7		PGE	211, 239, 250, 252, 253
valid_range		DFNT_UINT8	2		PGE	0,3

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