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Description
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.
The following changes and improvements were implemented for inputs to MODIS Version 6 surface reflectance data products: (1) Improvements to the aerosol retrieval and correction algorithm along with new aerosol retrieval look-up tables, (2) 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, (3) Processes ocean bands to create a new Surface Reflectance Ocean product and provides Quality Assurance (QA) datasets for these bands, and (4) Improved discrimination of salt pans from cloud and snow, along with the inclusion of a salt pan flag in the QA band.
Land Processes Distributed Active Archive Center (LP DAAC)
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MODIS Adaptive Processing System, Terrestrial Information Systems Laboratory, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA (NASA/GSFC/SED/ESD/TISL/MODAPS)
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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Citation Copied
Vermote, E. (2015). MYD09A1 MODIS/Aqua Surface Reflectance 8-Day L3 Global 500m SIN Grid V006 [Data set]. NASA Land Processes Distributed Active Archive Center. https://doi.org/10.5067/MODIS/MYD09A1.006 Date Accessed: 2026-05-01
Vermote, Eric. “MYD09A1 MODIS/Aqua Surface Reflectance 8-Day L3 Global 500m SIN Grid V006.” NASA Land Processes Distributed Active Archive Center, 2015. doi:10.5067/MODIS/MYD09A1.006. Date Accessed: 2026-05-01
Vermote, Eric. MYD09A1 MODIS/Aqua Surface Reflectance 8-Day L3 Global 500m SIN Grid V006. NASA Land Processes Distributed Active Archive Center, 2015, doi:10.5067/MODIS/MYD09A1.006. Date Accessed: 2026-05-01
File Naming Convention
MYD09A1.A2002273.h35v10.006.2015151145110.hdf
The file name begins with the Product Short Name (MYD09A1) followed by the Julian Date of Acquisition formatted as AYYYYDDD (A2002273), the Tile Identifier which is horizontal tile and vertical tile provided as hXXvYY (h35v10), the Version of the data collection (006), the Julian Date and Time of Production designated as YYYYDDDHHMMSS (2015151145110), and the Data Format (hdf).
Learn to interpret Moderate Resolution Imaging Spectroradiometer (MODIS) Surface Reflectance data quality via Quality Assurance bits, tools, and resources.
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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.
