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Full catalog/M2T1NXCHM
M2T1NXCHM·v5.12.4·dataset

Modeled carbon monoxide and ozone near the surface (hourly)

MERRA-2 tavg1_2d_chm_Nx: 2d,1-Hourly,Time-Averaged,Single-Level,Assimilation,Carbon Monoxide and Ozone Diagnostics 0.625 x 0.5 degree V5.12.4 (M2T1NXCHM) at GES DISC
atmosphere NASA GES_DISC Level 4 active
In plain English

What it measures. Modeled amounts of carbon monoxide and ozone in the air, including how much carbon monoxide is being emitted, produced, and left near the surface, plus the total column of ozone overhead, reported every hour.

How it's made. Not a direct satellite snapshot but output from NASA's MERRA-2 reanalysis, which blends a weather-and-chemistry model with decades of observations onto a global grid.

How & where you'd use it. Handy for studying air pollution patterns and atmospheric chemistry over time, and for filling in places and moments where direct measurements are missing.

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

M2T1NXCHM (or tavg1_2d_chm_Nx) is an hourly time-averaged 2-dimensional 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 data field is time-stamped with the central time of an hour starting from 00:30 UTC, e.g.: 00:30, 01:30, … , 23:30 UTC. 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

m2t1nxchm_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="M2T1NXCHM",
    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.