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Description

The MYD09GA Version 6 data product was decommissioned on July 31, 2023. Users are encouraged to use the MYD09GA Version 6.1 data product.

The MYD09GA Version 6 product provides an estimate of the surface spectral reflectance of Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Bands 1 through 7, corrected for atmospheric conditions such as gasses, aerosols, and Rayleigh scattering. Provided along with the 500 meter (m) surface reflectance, observation, and quality bands are a set of ten 1 km observation bands and geolocation flags. The reflectance layers from the MYD09GA are used as the source data for many of the MODIS land products.

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 provide 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.

Product Summary

Platforms
Aqua
Instruments
MODIS
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Spatial Resolution
500 Meters x 500 Meters
Geographic Region
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
GEODETIC
Temporal Extent
2002-07-04 to 2023-02-26
Temporal Resolution
1 Day
Data Partner
Land Processes Distributed Active Archive Center (LP DAAC) ,
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)
Concept ID
C2763370201-LPCLOUD
Data State
DEPRECATED
Number of Files/Granules
0
Processing Level
2G
Published
Updated
Science Keywords
Reflectance

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.

Copy Citation

Vermote, E., & Wolfe, R. (2015). MYD09GA MODIS/Aqua Surface Reflectance Daily L2G Global 1kmand 500m SIN Grid V006 [Data set]. NASA Land Processes Distributed Active Archive Center. https://doi.org/10.5067/MODIS/MYD09GA.006 Date Accessed: 2025-12-16

File Naming Convention

MYD09GA.A2002281.h03v07.006.2015151091940.hdf

The file name begins with the Product Short Name (MYD09GA) followed by the Julian Date of Acquisition formatted as AYYYYDDD (A2002281), the Tile Identifier which is horizontal tile and vertical tile provided as hXXvYY (h03v07), the Version of the data collection (006), the Julian Date and Time of Production designated as YYYYDDDHHMMSS (2015151091940), and the Data Format (hdf).

Documents

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
gflags_1 Geolocation flags Bit Field uint8 255 0 to 248 N/A
granule_pnt _1 Granule pointer N/A uint8 255 0 to 254 N/A
iobs_res_1 Observation number N/A uint8 255 0 to 254 N/A
num_observations_1km Number of observations within a  pixel N/A int8 -1 0 to 127 N/A
num_observations_500m Number of observations per 500m pixel N/A int8 -1 0 to 127 N/A
obscov_500m_1 Observation coverage Percent int8 -1 0 to 100 0.01
orbit_pnt_1 Orbit pointer N/A int8 -1 0 to 15 N/A
QC_500m_1 Surface Reflectance 500m Quality Assurance Bit Field uint32 787410671 0 to 4294966019 N/A
q_scan_1 250m scan value information N/A uint8 255 0 to 254 N/A
Range_1 Distance to sensor Meters uint16 0 27000 to 65535 25
SensorAzimuth_1 Azimuth angle to sensor Degree int16 -32767 -18000 to 18000 0.01
SensorZenith_1 Zenith angle to sensor Degree int16 -32767 0 to 18000 0.01
SolarAzimuth_1 Azimuth angle to sun Degree int16 -32767 -18000 to 18000 0.01
SolarZenith_1 Zenith angle to sun Degree int16 -32767 0 to 18000 0.01
state_1km_1 1km Reflectance Data State QA Bit Field uint16 65535 0 to 57335 N/A
sur_refl_b01_1 Surface Reflectance Band 1 N/A int16 -28672 -100 to 16000 0.0001
sur_refl_b02_1 Surface Reflectance Band 2 N/A int16 -28672 -100 to 16000 0.0001
sur_refl_b03_1 Surface Reflectance Band 3 N/A int16 -28672 -100 to 16000 0.0001
sur_refl_b04_1 Surface Reflectance Band 4 N/A int16 -28672 -100 to 16000 0.0001
sur_refl_b05_1 Surface Reflectance Band 5 N/A int16 -28672 -100 to 16000 0.0001
sur_refl_b06_1 Surface Reflectance Band 6 N/A int16 -28672 -100 to 16000 0.0001
sur_refl_b07_1 Surface Reflectance Band 7 N/A int16 -28672 -100 to 16000 0.0001
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