MODIS/Aqua Daily Surface Reflectance at 500m and 1km Resolution

NASA's MYD09GA Version 6 dataset provides daily global surface spectral reflectance estimates from the Aqua MODIS satellite for Bands 1-7, corrected for atmospheric gases, aerosols, and Rayleigh scattering. This product, now decommissioned in favor of Version 6.1, served as foundational source data for many downstream MODIS land products like albedo and vegetation indices. It includes 500-meter reflectance bands alongside 1-kilometer observation bands and geolocation flags.

Use Cases

• Generating land surface albedo and bidirectional reflectance distribution function (BRDF) models using the 500m surface reflectance bands.
• Calculating vegetation indices like NDVI by utilizing the corrected spectral reflectance in the red and near-infrared bands.
• Monitoring surface changes over time by analyzing the daily global time-series of reflectance data.
• Improving snow, cloud, and cloud shadow detection algorithms using the provided observation and quality assurance bands.
• Assessing aerosol loading over land surfaces, though with noted flagging issues in Collection 6.

Strengths

• Provides data at two spatial resolutions: 500m for surface reflectance and 1km for observation bands, offering flexibility for analysis.
• Includes atmospheric correction for gases, aerosols, and Rayleigh scattering, improving data utility for land surface studies.
• Collection 6.1 reprocessing implemented corrections for a known high aerosol flagging issue, indicating ongoing quality refinement.
• Serves as the direct source data for multiple authoritative MODIS land products, demonstrating its foundational role.

Limitations

• The primary Version 6 product has been decommissioned (July 31, 2023), directing users to a newer version.
• Collection 6 data contains a known issue where retrievals may be incorrectly flagged as 'High Aerosol' over bright surfaces and high view angles.
• Key metadata such as row count, column names, and precise data volume are unavailable from the provided sources.

Provenance

Source

National Aeronautics and Space Administration (NASA)

Collection Method

Satellite remote sensing via the Aqua spacecraft's Moderate Resolution Imaging Spectroradiometer (MODIS) sensor.

Time Range

null

Freshness

2026-03-12 23:47:00.918060

Geography

Global