The NASA Suomi National Polar-Orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) Land Surface Temperature and Emissivity (LST&E) Version 1 swath product (VNP21) is produced daily in 6-minute temporal increments of satellite acquisition. The VNP21 product uses a physics-based algorithm to dynamically retrieve both the LST and emissivity simultaneously for VIIRS thermal infrared bands M14 (8.55 µm), M15 (10.76 µm), and M16 (12 µm) at a spatial resolution of 750 meters.
The VNP21 product is developed synergistically with the Moderate Resolution Imaging Spectroradiometer (MODIS) LST&E Version 6 product (MOD21) using the same input atmospheric products and algorithmic approach based on the ASTER Temperature Emissivity Separation (TES) technique. The TES algorithm is combined with an improved Water Vapor Scaling (WVS) atmospheric correction scheme to stabilize the retrieval during very warm and humid conditions. 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. VIIRS LST&E products are available two months after acquisition due to latency of data inputs. Additional details regarding the method used to create this Level 2 (L2) product are available in the Algorithm Theoretical Basis Document (ATBD).
Provided in the VNP21 product are layers for LST, quality control, emissivity for bands M14, M15, and M16, LST&E errors, view angle, ASTER Global Emissivity Dataset (GED), Precipitable Water Vapor (PWV), ocean-land mask, latitude, and longitude. A low-resolution browse image for LST is also available for each VNP21 granule.
|File Size||~100 MB|
|Temporal Resolution||< Daily|
|Temporal Extent||2012-01-19 to Present|
|Coordinate System||None (Swath)|
|Geographic Dimensions||3060 km x 3060 km|
|Number of Science Dataset (SDS) Layers||15|
|Columns/Rows||3200 x 3232|
|Pixel Size||750 m|
|SDS Name||Description||Units||Data Type||Fill Value||No Data Value||Valid Range||Scale Factor||Additional Offset|
|LST||Land Surface Temperature||Kelvin||16-bit unsigned integer||0||N/A||7500 to 65535||0.02||N/A|
|QC||Quality control for LST and emissivity||N/A||16-bit unsigned integer||0||N/A||0 to 65535||N/A||N/A|
|Emis_14||M14 emissivity||N/A||8-bit unsigned integer||0||N/A||1 to 255||0.002||0.49|
|Emis_15||M15 emissivity||N/A||8-bit unsigned integer||0||N/A||1 to 255||0.002||0.49|
|Emis_16||M16 emissivity||N/A||8-bit unsigned integer||0||N/A||1 to 255||0.002||0.49|
|LST_err||Land Surface Temperature error||Kelvin||8-bit unsigned integer||0||N/A||1 to 255||0.04||N/A|
|Emis_14_err||M14 emissivity error||N/A||16-bit unsigned integer||0||N/A||0 to 65535||0.0001||N/A|
|Emis_15_err||M15 emissivity error||N/A||16-bit unsigned integer||0||N/A||0 to 65535||0.0001||N/A|
|Emis_16_err||M16 emissivity error||N/A||16-bit unsigned integer||0||N/A||0 to 65535||0.0001||N/A|
|View_angle||VIIRS view angle for current pixel||Degree||8-bit unsigned integer||255||N/A||0 to 180||0.5||N/A|
|Emis_ASTER||ASTER GED Emissivity (minimum of 5 band values)||N/A||8-bit unsigned integer||0||N/A||1 to 255||0.002||0.49|
|PWV||Precipitable Water Vapor||cm||16-bit unsigned integer||0||N/A||0 to 65535||0.001||N/A|
|oceanpix||Ocean-land mask||N/A||8-bit unsigned integer||N/A||N/A||0 to 2||N/A||N/A|
|latitude||Pixel Latitude||Degree||32-bit floating point||-999||N/A||-90 to 90||N/A||N/A|
|longitude||Pixel Longitude||Degree||32-bit floating point||-999||N/A||-180 to 180||N/A||N/A|
No known issues.