A global Land Surface Temperature image from the VJ121C1 product on May 12, 2020.
View full-size imageThe NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) Land Surface Temperature and Emissivity (LST&E) Climate Modeling Grid Version 2 product (VJ121C) is compiled daily from daytime Level 2 Gridded (L2G) intermediate products. The L2G process maps the daily VJ121 swath granules onto a sinusoidal MODIS grid and stores all observations overlapping a gridded cell for a given day. The VJ121C1 algorithm sorts through all these observations for each cell and estimates the final LST value as an average from all cloud-free observations that have good LST accuracies. The 0.05 degree (5,600 m) dataset is derived through resampling the native 750 meter VIIRS resolution in the input product.
The overall objective for NASA VIIRS products is to ensure the algorithms and products are compatible with the MODIS Terra and Aqua algorithms to promote the continuity of the Earth Observation System (EOS) mission. Additional details regarding the method used to create this Level 3 (L3) product are available in the Algorithm Theoretical Basis Document (ATBD).
The VJ121C1 product contains 25 Science Datasets (SDS): LST, quality control, view zenith angle, and time of observation for both day and night observations along with emissivity for bands M14, M15, and M16. Low-resolution browse images for day and night LST are also available for each VJ121C1 granule.
More details can be found in this VIIRS Land V2 Changes document.
Validation at stage 1 has been achieved for the VIIRS Land Surface Temperature and Emissivity product suite. Visit VIIRS Land Product Quality Assessment Product Maturity for information on product maturity status.
Characteristic | Description |
---|---|
Collection | NOAA-20 VIIRS |
DOI | 10.5067/VIIRS/VJ121C1.002 |
File Size | ~2.05 MB |
Temporal Resolution | Daily |
Temporal Extent | 2018-01-01 to Present |
Spatial Extent | Global |
Coordinate System | Geographic Latitude and Longitude |
Datum | N/A |
File Format | HDF-EOS5 |
Geographic Dimensions | Global |
Characteristic | Description |
---|---|
Number of Science Dataset (SDS) Layers | 25 |
Columns/Rows | 7200 x 3600 |
Pixel Size | 5600 m |
SDS Name | Description | Units | Data Type | Fill Value | No Data Value | Valid Range | Scale Factor | Offset |
---|---|---|---|---|---|---|---|---|
Count_Day | Count of Daytime Input Values | N/A | 16-bit unsigned integer | 0 | N/A | 1 to 65535 | N/A | N/A |
Count_Night | Count of Nighttime Input Values | N/A | 16-bit unsigned integer | 0 | N/A | 1 to 65535 | N/A | N/A |
Day_View_Angle | Average Daytime View Zenith Angle | Degree | 8-bit unsigned integer | 255 | N/A | 0 to 130 | N/A | -65 |
Day_View_Time | Average Daytime View Time | Hours | 8-bit unsigned integer | 255 | N/A | 0 to 240 | 0.2 | N/A |
Emis_14_Day | Average Daytime Band 14 Emissivity | N/A | 8-bit unsigned integer | 0 | N/A | 1 to 255 | 0.002 | 0.49 |
Emis_14_Day_err | Root-mean-square error Daytime Band 14 Emissivity | N/A | 16-bit unsigned integer | 0 | N/A | 1 to 65535 | 0.0001 | 0 |
Emis_14_Night | Average Nighttime Band 14 Emissivity | N/A | 8-bit unsigned integer | 0 | N/A | 1 to 255 | 0.002 | 0.49 |
Emis_14_Night_err | Root-mean-square error Nighttime Band 14 Emissivity | N/A | 16-bit unsigned integer | 0 | N/A | 1 to 65535 | 0.0001 | 0 |
Emis_15_Day | Average Daytime Band 15 Emissivity | N/A | 8-bit unsigned integer | 0 | N/A | 1 to 255 | 0.002 | 0.49 |
Emis_15_Day_err | Root-mean-square-error Daytime Band 15 Emissivity | N/A | 16-bit unsigned integer | 0 | N/A | 1 to 65535 | 0.0001 | 0 |
Emis_15_Night | Average Nighttime Band 15 Emissivity | N/A | 8-bit unsigned integer | 0 | N/A | 1 to 255 | 0.002 | 0.49 |
Emis_15_Night_err | Root-mean-square-error Nighttime Band 15 Emissivity | N/A | 16-bit unsigned integer | 0 | N/A | 1 to 65535 | 0.0001 | 0 |
Emis_16_Day | Average Daytime Band 16 Emissivity | N/A | 8-bit unsigned integer | 0 | N/A | 1 to 255 | 0.002 | 0.49 |
Emis_16_Day_err | Root-mean-square-error Daytime Band 16 Emissivity | N/A | 16-bit unsigned integer | 0 | N/A | 1 to 65535 | 0.0001 | 0 |
Emis_16_Night | Average Nighttime Band 16 Emissivity | N/A | 8-bit unsigned integer | 0 | N/A | 1 to 255 | 0.002 | 0.49 |
Emis_16_Night_err | Root-mean-square-error Nighttime Band 16 Emissivity | N/A | 16-bit unsigned integer | 0 | N/A | 1 to 65535 | 0.0001 | 0 |
LST_Day | Average Daytime Land Surface Temperature | Kelvin | 16-bit unsigned integer | 0 | N/A | 7500 to 65535 | 0.02 | 0 |
LST_Day_err | Root-mean-square-error Daytime Land Surface Temperature | Kelvin | 8-bit unsigned integer | 0 | N/A | 1 to 255 | 0.04 | 0 |
LST_Night | Average Nighttime Land Surface Temperature | Kelvin | 16-bit unsigned integer | 0 | N/A | 7500 to 65535 | 0.02 | 0 |
LST_Night_err | Root-mean-square-error Nighttime Land Surface Temperature | Kelvin | 8-bit unsigned integer | 0 | N/A | 1 to 255 | 0.04 | 0 |
Night_View_Angle | Average Nighttime View Zenith Angle | Degree | 8-bit unsigned integer | 255 | N/A | 0 to 130 | N/A | -65 |
Night_View_Time | Average Nighttime View Time | Hours | 8-bit unsigned integer | 255 | N/A | 0 to 240 | 0.2 | N/A |
Percent_land_in_grid | Percent of Land Detections in Grid Cell | Percent | 8-bit unsigned integer | 255 | N/A | 0 to 100 | N/A | 0 |
QC_Day | Quality Control for Daytime LST and Emissivity | N/A | 8-bit unsigned integer | N/A | N/A | 0 to 255 | N/A | N/A |
QC_Night | Quality Control for Nighttime LST and Emissivity | N/A | 8-bit unsigned integer | N/A | N/A | 0 to 255 | N/A | N/A |
The final quality bit for the output product reflects the lowest quality values from all observations that went into the final average. The bit flags for the QC layer are defined in Table 9 of the User Guide.
The quality layer is 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.
For additional information on product quality, refer to the VIIRS Land Product Quality website.
For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website and the User Guide.