Description
The MCD18A1 Version 6.2 is a Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua combined Downward Shortwave Radiation (DSR) gridded Level 3 product produced daily at 1 kilometer pixel resolution with estimates of DSR every 3 hours. DSR is incident solar radiation over land surfaces in the shortwave spectrum (300-4,000 nanometers) and is an important variable in land-surface models that address a variety of scientific and application issues. The MCD18 products are based on a prototyping algorithm that uses multi-temporal signatures of MODIS data to derive surface reflectance and then calculate incident DSR using the look-up table (LUT) approach. The LUTs consider different types of loadings of aerosols and clouds at a variety of illumination/viewing geometry. Global DSR products are generated from MODIS and geostationary satellite data. Additional details regarding the methodology used to create the data are available in the Algorithm Theoretical Basis Document (ATBD) (https://lpdaac.usgs.gov/documents/106/MCD18_ATBD.pdf)).
Provided in the MOD18A1 product are layers for instantaneous DSR array for each individual MODIS overpass and 3-hour DSR array along with a View Zenith Angle layer.
Validation at stage 1 (https://modis-land.gsfc.nasa.gov/MODLAND_val.html) has been achieved for the MODIS Surface Radiation products. Further details regarding MODIS land product validation for the MCD18 data products are available from the MODIS Land Team Validation site (https://modis-land.gsfc.nasa.gov/ValStatus.php?ProductID=MCD18).
The Version 6.2 Level-1B (L1B) products have been improved by undergoing various calibration changes that include: 1) MODIS shortwave infrared bands are included in the retrieval algorithm, which significantly reduces estimation uncertainties in cloud- and snow-covered pixels.
2) An improved climatology of surface reflectance was produced and used in the retrieval algorithm.
Resources
| Name | Format | Description | Link |
|---|---|---|---|
| Get a related visualization | HTML | Browse image for Earthdata Search | Open resource |
| This dataset's landing page | HTML | The LP DAAC product page provides information on Science Data Set layers and links for user guides, ATBDs, data access, tools, customer support, etc. | Open resource |
| Download this dataset | HTML | LP DAAC Data Pool provides direct access to available products via HTTPS. | Open resource |
| View documentation related to this dataset | HTML | The File Specification provides a description of the product file including Scientific Data Sets and their attributes. | Open resource |
| The dataset's project home page | HTML | The LP DAAC website provides detailed information on discovery, distribution, access, and support of land data products. | Open resource |
| View this dataset's algorithm theoretical basis document | The ATBD provides physical theory and mathematical procedures for the calculations used to produce the data products. | Open resource | |
| View this dataset's user's guide | The technical information in the User's Guide enables users to interpret and use the data products. | Open resource | |
| View this dataset's science data product validation documentation | HTML | Validation at stage 1 has been achieved for the MODIS Surface Radiation products. | Open resource |
| View this dataset's science data product validation documentation | HTML | Further details regarding MODIS land product validation for the MCD18 data products are available from the MODIS Land Team Validation site. | Open resource |
| Use OPeNDAP to access the dataset's data | HTML | Access data via Open-source Project for a Network Data Access Protocol | Open resource |
| Google Scholar search results | HTML | Search results for publications that cite this dataset by its DOI. | Open resource |
| Download this dataset | HTML | Earthdata Search allows users to search, discover, visualize, refine, and access NASA Earth Observation data. | Open resource |