The VNP09A1 surface reflectance band M5-M4-M3 data over the Western US, August 30 - September 6 , 2018.
View full-size imageThe 8-day Visible Infrared Imaging Radiometer Suite (VIIRS) surface reflectance (VNP09A1) Version 1 composite product provides an estimate of land surface reflectance from the NASA/NOAA Suomi National Polar-orbiting Partnership (Suomi 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.
Validation at stage 3 has been achieved for the VIIRS surface reflectance product suite. Visit VIIRS Land Product Quality Assessment Product Maturity for information on product maturity status.
| Characteristic | Description |
|---|---|
| Collection | Suomi NPP VIIRS |
| DOI | 10.5067/VIIRS/VNP09A1.001 |
| File Size | ~24 MB |
| Temporal Resolution | Multi-Day |
| Temporal Extent | 2012-01-17 to 2024-06-16 |
| Spatial Extent | Global |
| Coordinate System | Sinusoidal |
| Datum | N/A |
| File Format | HDF-EOS5 |
| Geographic Dimensions | 1200 km x 1200 km |
| Characteristic | Description |
|---|---|
| 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 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.