MERRA-2 M2TCNXLTM: Monthly Climatological Long-Term Mean and Standard Deviation

M2TCNXLTM is a NASA GMAO-produced dataset of monthly climatological long-term means and standard deviations, derived from the MERRA-2 global atmospheric reanalysis. Version 2 is calculated from a 30-year reference period spanning January 1991 to December 2020, providing statistics for variables like 2-meter air temperature, wind components at multiple levels, precipitation, and sea level pressure. This dataset supports the analysis of interannual variability and the establishment of climate baselines.

Use Cases

• Calculating climate anomalies by comparing current observations to the 1991-2020 long-term mean.
• Analyzing interannual variability of surface temperature and precipitation using the provided standard deviations.
• Establishing a baseline wind climatology at levels from 2 meters to 250 hPa for energy or transport studies.
• Studying the hydrological cycle through long-term means of total precipitation, evaporation, and precipitable water vapor.

Strengths

• Derived from the authoritative NASA MERRA-2 reanalysis, which assimilates satellite-era observations.
• Based on a defined 30-year climatological reference period (1991-2020 for V2), a standard in climate science.
• Provides both the mean and standard deviation for key variables, enabling analysis of central tendency and variability.

Limitations

• Key metadata such as row count, column names, and exact file size are unavailable across all platform listings.
• There is a conflict in the 'last updated' metadata, with dates ranging from 2010 to 2026 across different sources.
• The license is ambiguously listed as 'other-license-specified' without explicit details provided.

Provenance

Source

NASA Global Modeling and Assimilation Office (GMAO)

Collection Method

Calculated from monthly Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) reanalysis data.

Time Range

1991-01 to 2020-12 (V2 calculation period); underlying MERRA-2 data covers 1980-present.

Freshness

2026-04-10 01:23:01.448658

Geography

Global