VIIRS/JPSS2 Land Surface Temperature/Emissivity Daily L3 Global 1km SIN Grid Night V002

The NOAA-21 Visible Infrared Imaging Radiometer Suite (VIIRS) Land Surface Temperature and Emissivity (LST&E) Night Version 2 product (VJ221A1N) is compiled daily from nighttime Level 2 Gridded (L2G) intermediate products.

The L2G process maps the daily ([VJ221](https://doi.org/10.5067/VIIRS/VJ221.002)) swath granules onto a sinusoidal MODIS grid and stores all observations overlapping a gridded cell for a given night. The VJ221A1 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 VJ221A1N product is developed synergistically with the Moderate Resolution Imaging Spectroradiometer (MODIS) LST&E Version 6.1 product ([MOD21A1N](https://doi.org/10.5067/MODIS/MOD21A1N.061)) 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 VJ221A1N product contains seven variables: 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 VJ221A1N granule.

Known Issues
* For complete information about known issues please refer to the [MODIS/VIIRS Land Quality Assessment website](https://landweb.modaps.eosdis.nasa.gov/knownissue?sensor=VIIRS&sat=J2&as=5200) and the User Guide.