MERRA-2 M2IUNXGAS: Global Aerosol Optical Depth Analysis

1980-present monthly diurnal means of aerosol optical depth assimilation produced by NASA's Global Modeling and Assimilation Office. The data consists of instantaneous 2-dimensional fields averaged every three hours, generated using the Goddard Earth Observing System Model version 5.12.4. It is updated with a latency of approximately three weeks after the end of each month.

Use Cases

• Modeling aerosol transport and climate forcing based on assimilation analysis data.
• Analyzing diurnal cycles of atmospheric aerosols based on three-hourly instantaneous means.
• Studying long-term trends in global aerosol optical depth based on data from 1980 onward.
• Validating satellite-derived aerosol measurements based on reanalysis assimilation increments.

Strengths

• Long-term temporal coverage from 1980 to present.
• High temporal resolution with data fields every three hours.
• Produced by NASA's Global Modeling and Assimilation Office using the GEOS model.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.

Provenance

Source

National Aeronautics and Space Administration

Collection Method

Global atmospheric reanalysis assimilation using the Goddard Earth Observing System Model.

Time Range

1980-present

Freshness

Updated with ~3 week latency after month end; last metadata update 2026-03-13.

Geography

Global, 0.625 x 0.5 degree resolution