VNP09A1 v001

VIIRS/NPP Surface Reflectance 8-Day L3 Global 1 km SIN Grid


PI: Eric Vermote

Description

The 8-day Visible Infrared Imaging Radiometer Suite (VIIRS) surface reflectance (VNP09A1) Version 1 composite product provides an estimate of land surface reflectance from the Suomi National Polar-Orbiting Partnership (S-NPP) VIIRS sensor for nine moderate resolution bands (M1 - M5, M7, M8, M10, M11) at nominal 1 kilometer resolution (~926 meter). The 1 kiliometer dataset is derived through resampling the native 750 meter VIIRS resolution in the Level 2 input product. The data are corrected for atmospheric conditions such as the effects of molecular gases, including ozone and water vapor, and for the effects of atmospheric aerosols. Each pixel represents the best possible Level 2G observation during an 8-day period that is selected on the basis of high observation coverage, low sensor angle, the absence of clouds or cloud shadow, and aerosol loading. Included in the product along with the nine reflectance bands are day of year, reflectance band quality, control, reflectance state quality assurance, relative azimuth angle, sensor zenith angle, and solar zenith angle layers.

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Characteristics

Product Maturity

VIIRS surface reflectance products have reached maturity level of stage 1 validation. Visit VIIRS Land Product Quality Assessment product maturity for additional information on validation and product maturity status.

Collection and Granule

Collection

Characteristic Description
CollectionS-NPP VIIRS
DOI10.5067/VIIRS/VNP09A1.001
File Size~23 MB
Temporal ResolutionMulti-Day
Temporal Extent2012-01-17 to Present
Spatial ExtentGlobal
Coordinate SystemSinusoidal
DatumN/A
File FormatHDF-EOS
Geographic Dimensions1200 km x 1200 km

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers15
Columns/Rows1200 x 1200
Pixel Size1000 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
RelativeAzimuth Relative Azimuth Angle Degree 16-bit signed integer 0 N/A -18000 to 18000 0.01
SolarZenith Solar Zenith Angle Degree 16-bit signed integer 0 N/A 0 to 18000 0.01
SensorZenith SensorZenith Angle Degree 16-bit signed integer 0 N/A 0 to 18000 0.01
SurfReflect_Day_Of_Year Day of Year Julian day 16-bit unsigned integer 65535 N/A 1 to 366 N/A
SurfReflect_M1_1 1 km Surface Reflectance Band M1 N/A 16-bit signed integer -28672 N/A -100 to 16000 0.0001
SurfReflect_M2_1 1 km Surface Reflectance Band M2 N/A 16-bit signed integer -28672 N/A -100 to 16000 0.0001
SurfReflect_M3_1 1 km Surface Reflectance Band M3 N/A 16-bit signed integer -28672 N/A -100 to 16000 0.0001
SurfReflect_M4_1 1 km Surface Reflectance Band M4 N/A 16-bit signed integer -28672 N/A -100 to 16000 0.0001
SurfReflect_M5_1 1 km Surface Reflectance Band M5 N/A 16-bit signed integer -28672 N/A -100 to 16000 0.0001
SurfReflect_M7_1 1 km Surface Reflectance Band M7 N/A 16-bit signed integer -28672 N/A -100 to 16000 0.0001
SurfReflect_M8_1 1 km Surface Reflectance Band M8 N/A 16-bit signed integer -28672 N/A -100 to 16000 0.0001
SurfReflect_M10_1 1 km Surface Reflectance Band M10 N/A 16-bit signed integer -28672 N/A -100 to 16000 0.0001
SurfReflect_M11_1 1 km Surface Reflectance Band M11 N/A 16-bit signed integer -28672 N/A -100 to 16000 0.0001
SurfReflect_State Surface Reflectance State Quality Assurance (QA) Bit Field 16-bit unsigned integer 65535 N/A 0 to 13311 N/A
SurfReflect_QC Surface Reflectance Band Quality Control (QC) Bit Field 32-bit unsigned integer 4294967295 N/A 0 to 2147483647 N/A

Product Quality

The bit field mappings for QC and State QA layers are provided under Section 3.3 Tables 18 and 19 of the User Guide.

The following metadata related changes have been made to the User Guide:

  • Valid Range of 0 to 2147483647 and Fill Value of 4294967295 for the SurfReflect_QC layer (Table 7).
  • Description of Bit 31 in the SurfReflect_QC layer changed from “Adjacency Correction Performed" to "Spare (Unused)" (Table 18).
  • Valid Range of 0 to 13311 for the SurfReflect_State layer (Table 7).
  • Description of Bits 10-11 in the SurfReflect_State layer changed from “Internal cloud algorithm flag” and “Internal fire algorithm flag” changed to "Spare (Unused)" (Table 19).

The following changes have been implemented in the data:

  • Fill Value for Surface Reflectance Bands changed from 0 to -28672 for forward processing as of May 25, 2017.
  • Fill Value for the SurfReflect_QC layer set to reflect 4294967295 for forward processing as of August 21, 2017.
  • Bit 30 “Atmospheric Correction Performed” in the SurfReflect_QC layer set to “Yes” for forward processing as of August 21, 2017.

For complete information about product quality, refer to the VIIRS Land Product Quality Assessment website.

Known Issues

The VIIRS Land Surface Reflectance product (VNP09) flags a larger number of retrievals as ‘High Aerosol’ in the quality layer as compared to the MODIS reflectance product. The inaccurately flagged high aerosol quality flags directly impact the quality of the downstream VIIRS BRDF Albedo product (VNP43) in the mid to high latitude, arid lands, and tropical vegetative regions.

Additional known issues for VIIRS Surface Reflectance data products can be found in Section 4.0 “Caveats and Known Problems” of the User Guide.

Documentation

Using the Data

E-Learning

R You Ready to Python? An Introduction to Working with Land Remote Sensing Data in R and Python

Getting Started with VIIRS Surface Reflectance Data Part 1: All About Accessing Data

Getting Started with VIIRS Surface Reflectance Data Part 2: Using the Data

Getting Started with VIIRS Surface Reflectance Data Part 3: Interpreting Quality Information

Land Ho! Exploring Earth’s Land Surface with Suomi NPP NASA VIIRS Land Data

Access Data

Citation

DOI: 10.5067/VIIRS/VNP09A1.001

About the Image

The VNP09A1 surface reflectance band M5-M4-M3 data over the Western US, August 30 - September 6 , 2018.

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