VIIRS/JPSS1 Actual and Potential Evapotranspiration Gap-Filled Yearly L4 Global 500m SIN Grid V002

The NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) Actual and Potential Evapotranspiration product is a gap-filled yearly composite dataset produced at 500 meter (m) pixel resolution. The VIIRS ET and PET algorithm is based on the Penman-Monteith equation, which includes inputs of daily meteorological reanalysis data along with VIIRS remotely sensed data products such as 8-day vegetation property dynamics and daily surface albedo.

The VJ116A3GF will be generated at the end of each year when the entire yearly 8-day VJ115A2H is available. Hence, the gap-filled VJ116A3GF is the improved VJ116A2, which has cleaned the poor-quality inputs from 8-day Leaf Area Index and Fraction of Photosynthetically Active Radiation (LAI/FPAR) based on the Quality Control (QC) label for every pixel. If any LAI/FPAR pixel did not meet the quality screening criteria, its value is determined through linear interpolation. However, users cannot get VJ116A3GF in near-real time because it will be generated only at the end of a given year.

Provided in the VJ116A3GF product are variables for composited Evapotranspiration (ET), Latent Heat Flux (LE), Potential ET (PET) and Potential LE (PLE) along with a quality control variable. Two low resolution browse images, ET and LE, are also available for each VJ116A3GF granule.

The pixel values for the two Evapotranspiration variables (ET and PET) are the sum for all days within the defined year, and the pixel values for the two Latent Heat variables (LE and PLE) are the average of all days within the defined year.

Known Issues
* Please refer to the [VIIRS Land Products website](https://viirsland.gsfc.nasa.gov/Products/NASA/ET_ESDR.html) and [MODIS/VIIRS Land Quality Assessment website](https://landweb.modaps.eosdis.nasa.gov/knownissue?sensor=VIIRS) for information about VJ116A3GF known issues.