The NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) Land Surface Temperature and Emissivity (LST&E) Version 2 swath product (VJ121) is produced daily in 6-minute temporal increments of satellite acquisition. The VJ121 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 VJ121 product is developed developed synergistically with the Moderate Resolution Imaging Spectroradiometer (MODIS) LST&E Version 6.1 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 VJ121 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 VJ121 granule.

Known Issues

• For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website and the User Guide.

Improvements/Changes from Previous Version

• Improved calibration algorithm and coefficients for entire NOAA-20 mission.
• Improved geolocation accuracy and applied updates to fix outliers around maneuver periods.
• Corrected the aerosol quantity flag (low, average, high) mainly over brighter surfaces in the mid- to high-latitudes such as desert and tropical vegetation areas. This has an impact on the retrieval of other downstream data products such as VNP13 Vegetation Indices and VNP43 Bidirectional Reflectance Distribution Function (BRDF)/Albedo.
• Improved cloud mask input product for corrections along coastlines and artifacts from use of coarse resolution climatology data.
• Replaced the land/water mask input product with the eight-class land/water mask from the VNP03 geolocation product that better aligns with MODIS.
• Replaced MERRA2 inputs with GEOS5.
• Included inland water body pixels to allow for LST retrieval over these areas.
• Introduced daily, 8-day, and monthly LST CMG products.
• More details can be found in this VIIRS Land V2 Changes document.