N: 90 S: -90 E: 180 W: -180
Description
The NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) Photosynthetically Active Radiation (PAR) Level 3 Climate Modeling Grid (CMG) product produced at 0.05 degree pixel resolution at daily intervals. PAR is the incident solar radiation in the visible spectrum (400-700 nanometers) and is a significant variable in land surface models (LSMs), receiving increased attention due to its importance for the management and operation of solar energy systems.
The VJ118 algorithm adapts the narrowband look-up table (LUT) approach to estimate PAR. The LUTs consider different types of loadings of aerosols and clouds at a variety of illumination/viewing geometry. The Algorithm Theoretical Basis Document (ATBD) is forthcoming and will provide additional details regarding the methodology used to create the data.
The VJ118C2 product is aggregated from VJ118A2 files and includes one set of global 3-hour PAR variables and one set of daily mean PAR.
Version Description
Product Summary
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.
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File Naming Convention
The file name begins with the Product Short Name (VJ118C2) followed by the Julian Date of Acquisition formatted as AYYYYDDD (A2025198), the Version of the data collection (002), the Julian Date and Time of Production designated as YYYYDDDHHMMSS (2025210070105), and the Data Format (h5).
Documents
USER'S GUIDE
PRODUCT QUALITY ASSESSMENT
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 Sort descending | Description | Units | Data Type | Fill Value | Valid Range | Scale Factor |
|---|---|---|---|---|---|---|
| 3hour_PAR | 3-hour mean PAR | W/m² | float32 | -1 | 0 to 700 | N/A |
| Daily_Mean_PAR | Daily mean PAR | W/m² | float32 | -1 | 0 to 700 | N/A |