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Full catalog/M2C0NXCTM
M2C0NXCTM·v5.12.4·dataset

Fixed background settings for the weather model (MERRA-2)

MERRA-2 const_2d_ctm_Nx: Constant Model Parameters for Usage by CTM 0.625 x 0.5 degree V5.12.4 (M2C0NXCTM) at GES DISC
atmosphere NASA GES_DISC Level 4
In plain English

What it measures. Holds fixed background settings for a weather/chemistry model rather than live observations, such as what fraction of each map cell is lake, land, ice, or ocean.

How it's made. Part of NASA's MERRA-2 reanalysis, generated by the GEOS model and stored on a roughly half-degree global grid.

How & where you'd use it. A behind-the-scenes input for atmospheric chemistry modeling, used by specialists rather than read directly by most people.

What's measured

ATMOSPHERE › ALTITUDE › GEOPOTENTIAL HEIGHT

Coverage & cadence

  • Time span1980-01-01 → 2020-12-31
  • Measured byMERRA-2 (NOT APPLICABLE)
  • Processing levelLevel 4
  • Spatial extent-180, -90, 180, 90
  • StatusCOMPLETE

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

M2C0NXCTM (or const_2d_ctm_Nx) is a data collection in Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2). This collection consists of 2-dimensional constant model parameters for usage by the chemistry transport model (CTM), such as the fraction of lake, land, ice, or ocean within a model grid cell. 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. 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

m2c0nxctm_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="M2C0NXCTM",
    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.