The VNP09H1 surface reflectance band I3-I2-I1 data over the western United States, August 30 - September 6, 2018.View full-size image
The 8-day Visible Infrared Imaging Radiometer Suite (VIIRS) Surface Reflectance (VNP09H1) Version 1 composite product provides an estimate of land surface reflectance from the Suomi National Polar-orbiting Partnership (Suomi NPP) VIIRS sensor for three imagery bands (I1, I2, I3) at nominal 500 meter resolution (~463 meter). The 500 meter dataset is derived through resampling the native 375 meter VIIRS resolution in the L2 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, which is selected on the basis of high observation coverage, low sensor angle, the absence of clouds or cloud shadow, and aerosol loading. The three reflectance bands, this product includes a state quality assurance (QA) layer and a reflectance band quality layer.
Validation at stage 1 has been achieved for the VIIRS surface reflectance product suite. Visit VIIRS Land Product Quality Assessment Product Maturity for information on product maturity status.
|Collection||Suomi NPP VIIRS|
|File Size||~26 MB|
|Temporal Extent||2012-01-17 to Present|
|Geographic Dimensions||1200 km x 1200 km|
|Number of Science Dataset (SDS) Layers||5|
|Columns/Rows||2400 x 2400|
|Pixel Size||500 m|
|SDS Name||Description||Units||Data Type||Fill Value||No Data Value||Valid Range||Scale Factor|
|SurfReflect_I1||500 m Surface Reflectance Band I1||N/A||16-bit signed integer||-28672||N/A||-100 to 16000||0.0001|
|SurfReflect_I2||500 m Surface Reflectance Band I2||N/A||16-bit signed integer||-28672||N/A||-100 to 16000||0.0001|
|SurfReflect_I3||500 m Surface Reflectance Band I3||N/A||16-bit signed integer||-28672||N/A||-100 to 16000||0.0001|
|SurfReflect_State_500m||Surface Reflectance State Quality Assurance (QA)||Bit Field||16-bit unsigned integer||65535||N/A||0 to 13311||N/A|
|SurfReflect_QC_500m||Surface Reflectance Band Quality Control (QC)||Bit Field||16-bit unsigned integer||65535||N/A||0 to 32767||N/A|
The bit field mappings for QC and State QA layers are provided in Section 3.3 Tables 17 and 19 of the User Guide.
The Quality Control (QC) and State QA layers are stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret the quality layer.
Quality assurance information should be considered when determining the usability of data for a particular science application. The ArcGIS MODIS-VIIRS Python Toolbox contains tools capable of decoding quality data layers while producing thematic quality raster files for each quality attribute.
In addition to data access and transformation processes, AppEEARS also has the capability to unpack and interpret the quality layers.
The following metadata related changes have been made to the User Guide:
The following changes have been implemented in the data:
The VNP09 User Guide V1.1 remains available for data processed prior to August 2017.
For complete information about product quality, refer to the VIIRS Land Product Quality Assessment website.
The VIIRS Land Surface Reflectance product (VNP09) may incorrectly flag retrievals as ‘High Aerosol’ over brighter surfaces and at higher view angles. This will impact the downstream VIIRS BRDF/Albedo (VNP43) and Vegetation Index (VNP13) data products which use the aerosol quantity flag to screen out high aerosol values.
Corrections will be implemented in Collection 2 reprocessing in 2022.
For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website and in Section 4.0 “Caveats and Known Problems” of the User Guide.