VNP09GA v001

VIIRS/NPP Surface Reflectance Daily L2G Global 1 km and 500 m SIN Grid


PI: Eric Vermote

Description

The Visible Infrared Imaging Radiometer Suite (VIIRS) daily surface reflectance (VNP09GA) Version 1 product provides an estimate of land surface reflectance from the Suomi National Polar-Orbiting Partnership (S-NPP) VIIRS sensor. Data are provided for three imagery bands (I1-I3) at nominal 500 meter resolution (~ 463 meter) and nine moderate resolution bands (M1-M5, M7, M8, M10, M11) at nominal 1 kilometer (~926 meter) resolution. The 500 meter and 1 kilometer datasets are derived through resampling the native 375 meter and 750 meter VIIRS resolutions, respectively, in the Level 2 input product. These bands are corrected for atmospheric conditions such as the effects of molecular gases, including ozone and water vapor, and for the effects of atmospheric aerosols.

The inputs to the surface reflectance algorithm are top-of-atmosphere reflectance for the VIIRS visible bands,the VIIRS cloud mask and aerosol product, aerosol optical thickness and atmospheric data obtained from the NOAA National Centers for Environmental Prediction (NCEP) reanalysis system. Along with the twelve reflectance bands are reflectance band quality, sensor azimuth angle,solar azimuth angle, sensor zenith angle, solar zenith angle, and observations layers. The reflectance layers from the VNP09GA data product are used as input data for many of the VIIRS land products.

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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/VNP09GA.001
File Size~100 MB
Temporal ResolutionDaily
Temporal Extent2012-01-19 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) Layers29
Columns/Rows2400 (500 m) and 1200 (1000 m) x 2400 (500 m) and 1200 (1000 m)
Pixel Size1000 m and 500 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
SensorZenith_1 Sensor Zenith Angle Degree 16-bit signed integer -32767 N/A 0 to 18000 0.01
SensorAzimuth_1 Sensor Azimuth Angle Degree 16-bit signed integer -32767 N/A -18000 to 18000 0.01
SolarZenith_1 Solar Zenith Angle Degree 16-bit signed integer -32767 N/A 0 to 18000 0.01
SolarAzimuth_1 Solar Azimuth Angle Degree 16-bit signed integer -32767 N/A -18000 to 18000 0.01
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
Land_QF1_1 Quality Flag 1 Bit Field 8-bit unsigned integer 255 N/A 0 to 255 N/A
Land_QF2_1 Quality Flag 2 Bit Field 8-bit unsigned integer 255 N/A 0 to 255 N/A
Land_QF3_1 Quality Flag 3 Bit Field 8-bit unsigned integer 255 N/A 0 to 255 N/A
Land_QF4_1 Quality Flag 4 Bit Field 8-bit unsigned integer 255 N/A 0 to 255 N/A
Land_QF5_1 Quality Flag 5 Bit Field 8-bit unsigned integer 255 N/A 0 to 255 N/A
Land_QF6_1 Quality Flag 6 Bit Field 8-bit unsigned integer 255 N/A 0 to 255 N/A
Land_QF7_1 Quality Flag 7 Bit Field 8-bit unsigned integer 255 N/A 0 to 255 N/A
num_observations_1km Number of observations 1 km N/A 8-bit signed integer -1 N/A 0 to 127 N/A
obscov_1km_1 Observations coverage 1 km Percent 8-bit signed integer -1 N/A 0 to 100 N/A
orbit_pnt_1 Orbit Pointer N/A 8-bit signed integer -1 N/A 0 to 15 N/A
I1_SurfRefl_1 500 m Surface Reflectance Band I1 N/A 16-bit signed integer -28672 N/A -100 to 16000 0.0001
I2_SurfRefl_1 500 m Surface Reflectance Band I2 N/A 16-bit signed integer -28672 N/A -100 to 16000 0.0001
I3_SurfRefl_1 500 m Surface Reflectance Band I3 N/A 16-bit signed integer -28672 N/A -100 to 16000 0.0001
num_observations_500m Number of observations 500 m N/A 8-bit signed integer -1 N/A 0 to 127 N/A
obscov_500m_1 Observation coverage 500 m Percent 8-bit signed integer -1 N/A 0 to 100 0.01
iobs_res_1 Observation number N/A 8-bit unsigned integer 255 N/A 0 to 254 N/A

Product Quality

The bit field mappings for Quality Flag (QF) layers 1 through 7 are provided in the User Guide under Section 3.3, Tables 10 through 16.

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” in the User Guide.

Documentation

Using the Data

E-Learning

Working with Daily NASA VIIRS Surface Reflectance Data

An Introduction to Suomi-NPP NASA VIIRS Data Products

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/VNP09GA.001

About the Image

The VNP09GA surface reflectance band M5-M4-M3 data over the western US from September 17, 2018.

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