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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).

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

Location
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
1980-01-01 to 2020-12-31
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
C1278787764-GES_DISC
Data State
ACTIVE
Number of Files/Granules
1
Processing Level
4
Published
Updated
Science Keywords
Geopotential Height

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 const_2d_ctm_Nx: Constant Model Parameters for Usage by CTM [Data set]. NASA Goddard Earth Sciences Data and Information Services Center. https://doi.org/10.5067/4Z3YUPM81GRJ Date Accessed: 2026-02-11

Documents

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
FRACI FRACI 1 float32 N/A N/A N/A
FRLAKE FRLAKE 1 float32 N/A N/A N/A
FRLAND FRLAND 1 float32 N/A N/A N/A
FRLANDICE FRLANDICE 1 float32 N/A N/A N/A
FROCEAN FROCEAN 1 float32 N/A N/A N/A
lat lat degrees_north float64 N/A N/A N/A
lon lon degrees_east float64 N/A N/A N/A
PHIS PHIS m+2 s-2 float32 N/A N/A N/A
time time minutes since 1980-01-15 12:00:00 int32 N/A N/A N/A
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