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Description

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

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.

Product Summary

Platforms
NOAA-20
Instruments
VIIRS
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Spatial Resolution
750 Meters x 750 Meters
Geographic Region
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
GEODETIC
Temporal Extent
2018-01-01 to Present
Temporal Resolution
1 Day
Data Partner
Land Processes Distributed Active Archive Center (LP DAAC) ,
Land Science Investigator-led Processing System, Terrestrial Information Systems Laboratory, Earth Sciences Division, Sciences and Exploration Directorate, Goddard Space Flight Center, NASA (NASA/GSFC/SED/ESD/TISL/LandSIPS)
Concept ID
C2545310883-LPCLOUD
Data State
ACTIVE
Number of Files/Granules
704499
Processing Level
2
Published
Updated
Science Keywords
Land Surface Temperature ,
Emissivity

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

Hulley, G., & Hook, S. (2023). VIIRS/JPSS1 Land Surface Temperature and Emissivity 6-Min L2 Swath 750m V002 [Data set]. NASA Land Processes Distributed Active Archive Center. https://doi.org/10.5067/VIIRS/VJ121.002 Date Accessed: 2025-12-14

File Naming Convention

VJ121.A2025224.0054.002.2025224111847.nc

The file name begins with the Product Short Name (VJ121) followed by the Julian Date of Acquisition formatted as AYYYYDDD (A2025224), the Hours and Minutes of Acquisition provided as HHMM (0054), the Version of the data collection (002), the Julian Date and Time of Production designated as YYYYDDDHHMMSS (2025224111847), and the Data Format (nc).

Documents

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
Emis_14 M14 emissivity N/A uint8 0 1 to 255 0.002
Emis_14_err M14 emissivity error N/A uint16 0 1 to 65535 0.0001
Emis_15 M15 emissivity N/A uint8 0 1 to 255 0.002
Emis_15_err M15 emissivity error N/A uint16 0 1 to 65535 0.0001
Emis_16 M16 emissivity N/A uint8 0 1 to 255 0.002
Emis_16_err M16 emissivity error N/A uint16 0 1 to 65535 0.0001
Emis_ASTER ASTER GED Emissivity (minimum of 5 band values) N/A uint8 0 1 to 255 0.002
latitude Pixel Latitude Degree float32 -999 -90 to 90 N/A
longitude Pixel Longitude Degree float32 -999 -180 to 180 N/A
LST Land Surface Temperature Kelvin uint16 0 7500 to 65535 0.02
LST_err Land Surface Temperature error Kelvin uint8 0 1 to 255 0.04
oceanpix Ocean-land mask N/A uint8 N/A 0 to 2 N/A
PWV Precipitable Water Vapor cm uint16 N/A 0 to 65535 0.001
QC Quality control for LST and emissivity N/A uint16 N/A 0 to 65535 N/A
View_angle VIIRS view angle for current pixel Degree uint8 255 0 to 180 0.5
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