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Description

The NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) Land Surface Temperature and Emissivity (LST&E) Night Version 2 product (VJ121A1N) is compiled daily from nighttime 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 night. The VJ121A1 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 nighttime average is weighted by the observation coverage for that cell. Only observations having observation coverage more than a certain threshold (15%) are considered for this averaging. The 1 kilometer dataset is derived through resampling the native 750 meter VIIRS resolution in the input product.

The VJ121A1N product is developed synergistically with the Moderate Resolution Imaging Spectroradiometer (MODIS) LST&E Version 6.1 product (MOD21A1N) using the same input atmospheric products and algorithmic approach. 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 VJ121A1N product contains seven Science Datasets (SDS): LST, quality control, emissivity for bands M14, M15, and M16, view zenith angle, and time of observation. A low-resolution browse image for LST is also available for each VJ121A1N granule.

Known Issues

Version Description

NOAA-20 (JPSS-1) VIIRS data products, designated as "VJ1", were introduced in VIIRS Version 2.

Product Summary

Platforms
NOAA-20
Instruments
VIIRS
Spatial Extent

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

Spatial Resolution
1000 Meters x 1000 Meters
Spatial Reference System(s)
VIIRS Sinusoidal Tiling System
Location
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
C2545310892-LPCLOUD
Data State
ACTIVE
Number of Files/Granules
1009801
Processing Level
3
Published
Updated
Science Keywords
Emissivity ,
Land Surface Temperature

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/Emissivity Daily L3 Global 1km SIN Grid Night V002 [Data set]. NASA Land Processes Distributed Active Archive Center. https://doi.org/10.5067/VIIRS/VJ121A1N.002 Date Accessed: 2026-02-15

File Naming Convention

VJ121A1N.A2025224.h19v08.002.2025225080511.h5

The file name begins with the Product Short Name (VJ121A1N) followed by the Julian Date of Acquisition formatted as AYYYYDDD (A2025224), the Tile Identifier which is horizontal tile and vertical tile provided as hXXvYY (h19v08), the Version of the data collection (002), the Julian Date and Time of Production designated as YYYYDDDHHMMSS (2025225080511), and the Data Format (h5).

Documents

Variables

The table below lists the variables contained within a single granule for this dataset. Variables often contain observed or derived geophysical measurements collected from a variety of sources, including remote sensing instruments on satellite and airborne platforms, field campaigns, in situ measurements, and model outputs. The terms variable, parameter, scientific data set, layer, and band have been used across NASA’s Earth science disciplines; however, variable is the designated nomenclature in NASA’s Common Metadata Repository (CMR). Variable metadata attributes such as Name, Description, Units, Data Type, Fill Value, Valid Range, and Scale Factor allow users to efficiently process and analyze the data. The full range of attributes may not be applicable to all variables. Additional information on variable attributes is typically available in the data, user guide, and/or other product documentation.

For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
Emis_14 Daily M14 emissivity N/A uint8 0 1 to 255 0.002
Emis_15 Daily M15 emissivity N/A uint8 0 1 to 255 0.002
Emis_16 Daily M16 emissivity N/A uint8 0 1 to 255 0.002
LST_1KM Daily 1 km Land Surface Temperature Kelvin uint16 0 7500 to 65535 0.02
QC Daily Quality control for LST and emissivity N/A uint16 N/A 0 to 65535 N/A
View_Angle View zenith angle of LST Degree uint8 255 0 to 130 N/A
View_Time Time of LST observation Hours uint8 255 0 to 240 0.1
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