Global 3-Hourly Cloud Diagnostics from NASA Atmospheric Reanalysis

MERRA-2 provides a 3-dimensional, 3-hourly time-averaged assimilation of cloud diagnostics across 72 atmospheric model layers. NASA's Global Modeling and Assimilation Office produced this reanalysis using the GEOS model, covering the period from 1980 to the present with approximately three weeks of latency.

Use Cases

• Analyze temporal trends in cloud fraction for radiation across the 72 model layers from 1980 onward.
• Model in-cloud ice or liquid water content for radiation using the 3-hourly assimilated diagnostics.
• Study vertical profiles of relative humidity and pressure thickness within the global atmospheric column.
• Validate satellite-derived cloud products against the assimilated, model-level cloud fraction data.

Strengths

• Covers over 40 years of global atmospheric data from 1980 to present.
• Provides data at a high temporal resolution of 3 hours (e.g., 01:30, 04:30 UTC).
• Offers detailed vertical resolution with diagnostics across 72 distinct model layers.

Limitations

• Data has a latency of approximately three weeks after the end of each month, limiting near-real-time analysis.
• The spatial resolution of 0.625 x 0.5 degrees may be too coarse for regional or micro-scale cloud studies.
• Reprocessing events change file names and contents, requiring careful version tracking.

Provenance

Source

NASA Global Modeling and Assimilation Office (GMAO) via the Goddard Earth Sciences Data and Information Services Center (GES DISC).

Collection Method

Produced by assimilating observational data into 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 at 0.625 x 0.5 degree resolution.