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Description

M2TMNXCHM (or tavgM_2d_chm_Nx) is a time-averaged 2-dimensional monthly mean data collection in Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2). This collection consists of assimilated carbon monoxide and ozone diagnostics, such as properties of carbon monoxide (column burden, emission, chemical production, and surface concentration), and total column ozone. The collection also includes variance of certain parameters.

MERRA-2 is the latest version of global atmospheric reanalysis for the satellite era produced by NASA Global Modeling and Assimilation Office (GMAO) using the Goddard Earth Observing System Model (GEOS) version 5.12.4. The dataset covers the period of 1980-present with the latency of ~3 weeks after the end of a month.

Data Reprocessing: Please check “Records of MERRA-2 Data Reprocessing and Service Changes” linked from the “Documentation” tab on this page. Note that a reprocessed data filename is different from the original file.

MERRA-2 Mailing List: Sign up to receive information on reprocessing of data, changing of tools and services, as well as data announcements from GMAO. Contact the GES DISC Help Desk (gsfc-dl-help-disc@mail.nasa.gov) to be added to the list.

Questions: If you have a question, please read "MERRA-2 File Specification Document", “MERRA-2 Data Access – Quick Start Guide”, and FAQs linked from the ”Documentation” tab on this page. If that does not answer your question, you may post your question to the NASA Earthdata Forum (forum.earthdata.nasa.gov) or email the GES DISC Help Desk (gsfc-dl-help-disc@mail.nasa.gov).

Version Description

The GEOS-5 model version used for processing MERRA-2

Product Summary

Platforms
MERRA-2
Instruments
NOT APPLICABLE
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Spatial Resolution
0.625 Decimal Degrees x 0.5 Decimal Degrees
Location
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
1980-01-01 to Present
Data Partner
Goddard Earth Sciences Data and Information Services Center (formerly Goddard DAAC), Terrestrial Information Systems Laboratory, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA (NASA/GSFC/SED/ESD/TISL/GESDI
Concept ID
C1276812852-GES_DISC
Data State
ACTIVE
Number of Files/Granules
555
Processing Level
4
Published
Updated
Science Keywords
Atmospheric Carbon Monoxide ,
Carbon Monoxide ,
Atmospheric Ozone

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

Global Modeling And Assimilation Office, & Pawson, S. (2015). MERRA-2 tavgM_2d_chm_Nx: 2d,Monthly mean,Time-Averaged,Single-Level,Assimilation,Carbon Monoxide and Ozone Diagnostics V5.12.4 [Data set]. NASA Goddard Earth Sciences Data and Information Services Center. https://doi.org/10.5067/WMT31RKEXK8I Date Accessed: 2026-05-02

Documents

Publications Citing This Dataset

Filters
Title Year Author Topic
Preterm births attributable to criteria air pollutant exposure in Partha, Debatosh B., Yasmin, Sumiya, Nath, Hrithik Carbon Monoxide, Geopotential Height, Tropopause, Methane, Atmospheric Ozone, Surface Pressure, Outgoing Longwave Radiation, Air Temperature, Upper Air Temperature, Humidity, Total Precipitable Water, Water Vapor, Water Vapor Profiles, Cloud Liquid Water/Ice, Cloud Height, Cloud Top Pressure, Cloud Top Temperature, Cloud Vertical Distribution, Emissivity, Skin Temperature, Sea Surface Temperature, Aerosols, Aerosol Extinction, Aerosol Optical Depth/Thickness, Angstrom Exponent, Aerosol Particle Properties, Carbonaceous Aerosols, Dust/Ash/Smoke, Organic Particles, Sulfate Particles, Sulfur Oxides, Sulfur Compounds, Sulfate, Sulfur Dioxide, Sulfur Oxides, Particulate Matter, Dimethyl Sulfide, Black Carbon, Sea Salt, PARTICULATE MATTER (PM 2.5), PARTICULATE MATTER (PM 10), PARTICULATE MATTER (PM 1.0), Atmospheric Carbon Monoxide, Population
Impacts of ambient air pollution exposure on child growth in East African countries Baharane, Valerien, Shatalov, Andrey Borisovich Atmospheric Ozone, Sea Level Pressure, Surface Pressure, U/V Wind Components, U/V Wind Components, Potential Vorticity, Vertical Wind Velocity/Speed, Vertical Profiles, Upper Air Temperature, Air Temperature, Relative Humidity, Specific Humidity, Atmospheric Water Vapor, Cloud Liquid Water/Ice, Altitude, Geopotential Height, Ozone Profiles, Aerosols, Aerosol Extinction, Aerosol Optical Depth/Thickness, Angstrom Exponent, Aerosol Particle Properties, Carbonaceous Aerosols, Dust/Ash/Smoke, Organic Particles, Sulfate Particles, Sulfur Oxides, Sulfur Compounds, Sulfate, Sulfur Dioxide, Sulfur Oxides, Particulate Matter, Dimethyl Sulfide, Black Carbon, Sea Salt, PARTICULATE MATTER (PM 2.5), PARTICULATE MATTER (PM 10), PARTICULATE MATTER (PM 1.0), Atmospheric Carbon Monoxide, Carbon Monoxide
Early-life environmental exposures and anaemia among children under age five in Sub-Saharan Africa: An insight from the Demographic & Health Surveys Amegbor, Prince M. Atmospheric Carbon Monoxide, Carbon Monoxide, Atmospheric Ozone, Vegetation Index, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI)
Geospatial analysis of COVID-19 lockdown effects on air quality in the South and Southeast Asian region Roy, Sanjoy, Saha, Monojit, Dhar, Bandhan, Pandit, Santa, Nasrin, Rubaiya Atmospheric Carbon Monoxide, Carbon Monoxide, Atmospheric Ozone
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Variables

The table below lists the variables contained within a single granule for this dataset. Variables often contain observed or derived geophysical measurements collected from a variety of sources, including remote sensing instruments on satellite and airborne platforms, field campaigns, in situ measurements, and model outputs. The terms variable, parameter, scientific data set, layer, and band have been used across NASA’s Earth science disciplines; however, variable is the designated nomenclature in NASA’s Common Metadata Repository (CMR). Variable metadata attributes such as Name, Description, Units, Data Type, Fill Value, Valid Range, and Scale Factor allow users to efficiently process and analyze the data. The full range of attributes may not be applicable to all variables. Additional information on variable attributes is typically available in the data, user guide, and/or other product documentation.

For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor Offset
COCL COCL kg m-2 float32 999999986991104 N/A N/A N/A
COEM COEM kg m-2 s-1 float32 999999986991104 N/A N/A N/A
COLS COLS kg m-2 s-1 float32 999999986991104 N/A N/A N/A
COPD COPD kg m-2 s-1 float32 999999986991104 N/A N/A N/A
COSC COSC 1e-9 float32 999999986991104 N/A N/A N/A
lat lat degrees_north float64 N/A N/A N/A N/A
lon lon degrees_east float64 N/A N/A N/A N/A
LWI LWI 1 float32 999999986991104 N/A N/A N/A
time time minutes since 2025-11-01 00:30:00 int32 N/A N/A N/A N/A
TO3 TO3 Dobsons float32 999999986991104 N/A N/A N/A
Var_COCL Var_COCL kg m-2 kg m-2 float32 999999986991104 N/A N/A N/A
Var_COEM Var_COEM kg m-2 s-1 kg m-2 s-1 float32 999999986991104 N/A N/A N/A
Var_COLS Var_COLS kg m-2 s-1 kg m-2 s-1 float32 999999986991104 N/A N/A N/A
Var_COPD Var_COPD kg m-2 s-1 kg m-2 s-1 float32 999999986991104 N/A N/A N/A
Var_COSC Var_COSC 1e-9 1e-9 float32 999999986991104 N/A N/A N/A
Var_LWI Var_LWI 1 1 float32 999999986991104 N/A N/A N/A
Var_TO3 Var_TO3 Dobsons Dobsons float32 999999986991104 N/A N/A N/A
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