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Full catalog/M2TMNXCHM
M2TMNXCHM·v5.12.4·dataset

Monthly carbon monoxide and ozone near the surface (MERRA-2)

MERRA-2 tavgM_2d_chm_Nx: 2d,Monthly mean,Time-Averaged,Single-Level,Assimilation,Carbon Monoxide and Ozone Diagnostics 0.625 x 0.5 degree V5.12.4 (M2TMNXCHM) at GES DISC
atmosphere NASA GES_DISC Level 4 active
In plain English

What it measures. Monthly averages of carbon monoxide and ozone in the air around the globe. For carbon monoxide it tracks things like how much is in a column of air overhead, how much is being emitted, how much is chemically produced, and how much sits near the ground; for ozone it gives the total amount overhead.

How it's made. It comes from MERRA-2, NASA's long-running reanalysis that blends satellite observations with a global atmospheric model to fill in a complete, gridded picture.

How & where you'd use it. Useful for tracking air quality and pollution patterns over time, comparing months and years, and feeding climate and atmospheric studies that need consistent global coverage.

What's measured

ATMOSPHERE › ATMOSPHERIC CHEMISTRY › CARBON AND HYDROCARBON COMPOUNDS › ATMOSPHERIC CARBON MONOXIDEATMOSPHERE › AIR QUALITY › CARBON MONOXIDEATMOSPHERE › ATMOSPHERIC CHEMISTRY › OXYGEN COMPOUNDS › ATMOSPHERIC OZONE

Coverage & cadence

  • Time span1980-01-01 → ongoing
  • Measured byMERRA-2 (NOT APPLICABLE)
  • Processing levelLevel 4
  • Spatial extent-180, -90, 180, 90
  • StatusACTIVE

What you can do with it

  • Map air pollutants — NO₂, aerosols, ozone
  • Track greenhouse gases and Earth's energy budget
  • Feed weather and air-quality analysis
Official 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).

Get the data

m2tmnxchm_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="M2TMNXCHM",
    version="5.12.4",
    bounding_box=(-122.5, 37.2, -121.8, 37.9),  # your area (W,S,E,N)
    temporal=("2024-01-01", "2024-12-31"),       # your dates
)
files = earthaccess.open(results)   # stream straight from GES_DISC
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.