Country-Level Monthly PM2.5 Concentrations Derived from MERRA-2

M2_TMAX_PM25 provides monthly mean surface concentrations of fine particulate matter (PM2.5) aggregated to country and territory levels. The data is a value-added product derived from NASA's MERRA-2 aerosol reanalysis model, calculated as the sum of organic carbon, black carbon, sulfate, sea salt, and dust components. It is produced by the GMAO and distributed via the GES DISC.

Use Cases

• Analyze long-term trends in country-level PM2.5 concentrations using the monthly mean time series.
• Compare population-weighted versus unweighted PM2.5 exposure estimates across different territories.
• Validate regional air quality models by comparing them with MERRA-2 derived aerosol component sums (organic carbon, black carbon, sulfate, sea salt, dust).
• Study the contribution of specific aerosol types, like sulfate or dust, to total PM2.5 levels in a given country.

Strengths

• Derived from the well-established MERRA-2 global atmospheric reanalysis model.
• Includes both population-weighted and unweighted PM2.5 estimates for country-level analysis.
• PM2.5 is calculated from a defined sum of five individual aerosol components.

Limitations

• Spatial resolution is limited to country-level aggregates, not high-resolution grids.
• Model-derived data may contain biases compared to ground-based monitoring station measurements.
• Specific temporal coverage, row count, and update frequency are not provided in the input.

Provenance

Source

NASA Global Modeling and Assimilation Office (GMAO), distributed by GES DISC.

Collection Method

Derived from the MERRA-2 aerosol monthly product M2TMNXAER_5.12.4, recast from the native model grid to country-level.

Geography

Global coverage aggregated to country and territory levels.