Monthly Surface Flux Diagnostics from NASA's Global Atmospheric Reanalysis

MERRA-2 provides a global atmospheric reanalysis from 1980 to the present, updated with a latency of about three weeks. NASA's Global Modeling and Assimilation Office produced this monthly mean collection of assimilated surface flux diagnostics, including total precipitation and surface air temperature. The data represents conditions at the model surface layer, approximately 60 meters above ground.

Use Cases

• Analyzing trends in total precipitation and bias-corrected total precipitation for global hydrological cycle studies.
• Modeling land-atmosphere interactions using surface air temperature and surface specific humidity fields.
• Studying surface wind speed patterns for renewable energy potential assessments.
• Investigating evaporation from turbulence to understand surface moisture fluxes.
• Calculating variance of key parameters to assess model uncertainty and data reliability.

Strengths

• Continuous global coverage from 1980 to present, providing over 40 years of data.
• Produced by NASA GMAO using the GEOS 5.12.4 model, an authoritative reanalysis system.
• Monthly temporal resolution on a 0.625 x 0.5 degree global grid.

Limitations

• Surface diagnostic heights vary with time and location (~60m), not representing ground-level conditions.
• Data undergoes reprocessing; filename changes can create versioning challenges.
• Assimilated model data contains inherent uncertainties and is not direct observation.

Provenance

Source

NASA Global Modeling and Assimilation Office (GMAO).

Collection Method

Assimilated reanalysis using the Goddard Earth Observing System Model (GEOS) version 5.12.4.

Time Range

1980 to present.

Freshness

Updated monthly with ~3 week latency.

Geography

Global coverage.