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.
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.
|File Size||~23 MB|
|Temporal Extent||2012-01-17 to Present|
|Geographic Dimensions||1200 km x 1200 km|
|Number of Science Dataset (SDS) Layers||15|
|Columns/Rows||1200 x 1200|
|Pixel Size||1000 m|
|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|
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:
The following changes have been implemented in the data:
For complete information about product quality, refer to the VIIRS Land Product Quality Assessment website.
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.