MODIS/Aqua Surface Reflectance 8-Day L3 Global 500m SIN Grid V006

The MYD09A1 Version 6 data product was decommissioned on July 31, 2023. Users are encouraged to use the MYD09A1 Version 6.1 data product. The Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua MYD09A1 Version 6 product provides an estimate of the surface spectral reflectance of Aqua MODIS Bands 1 through 7 corrected for atmospheric conditions such as gasses, aerosols, and Rayleigh scattering. Along with the seven 500 meter (m) reflectance bands are a quality variable and four observation bands. For each pixel, a value is selected from all the acquisitions within the 8-day composite period. The criteria for the pixel choice include cloud and solar zenith. When several acquisitions meet the criteria the pixel with the minimum channel 3 (blue) value is used. Known Issues * The Collection 6 MODIS Land Surface Reflectance product (MYD09) may incorrectly flag retrievals as ‘High Aerosol’ over brighter surfaces and at higher view angles. This will impact the downstream MODIS BRDF/Albedo (MCD43) and Vegetation Index (MOD13 and MYD13) data products which use the aerosol quantity flag to screen out high aerosol values. * Corrections were implemented in Collection 6.1 reprocessing. * For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website. Improvements/Changes from Previous Versions * Improvements to the aerosol retrieval and correction algorithm along with new aerosol retrieval look-up tables. * Refinements to the internal snow, cloud, and cloud shadow detection algorithms. Uses Bidirectional Reflectance Distribution Function (BRDF) database to better constrain the different threshold used. * Processes ocean bands to create a new Surface Reflectance Ocean product and provides Quality Assurance (QA) datasets for these bands. * Improved discrimination of salt pans from cloud and snow, along with the inclusion of a salt pan flag in the QA band.