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Full catalog/M2C0NXASM
M2C0NXASM·v5.12.4·dataset

Unchanging map features like land fraction (MERRA-2)

MERRA-2 const_2d_asm_Nx: 2d, constants 0.625 x 0.5 degree V5.12.4 (M2C0NXASM) at GES DISC
atmosphere NASA GES_DISC Level 4 active
In plain English

What it measures. A set of fixed, never-changing background map features, such as what fraction of each grid cell is lake, land, or ocean.

How it's made. Part of MERRA-2, NASA's satellite-era reanalysis built with the GEOS weather model; these are constant reference values rather than time-varying observations.

How & where you'd use it. A reference layer used alongside other MERRA-2 data so analyses know the basic land-and-water makeup of each grid cell; rarely used on its own.

What's measured

ATMOSPHERE › ALTITUDE › GEOPOTENTIAL HEIGHTOCEANS › SEA SURFACE TOPOGRAPHY

Coverage & cadence

  • Time span1980-01-01 → ongoing
  • 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

M2C0NXASM (or const_2d_asm_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, such as the fraction of lake, land, and 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

m2c0nxasm_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="M2C0NXASM",
    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.