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Description
M2I1NXASM (or inst1_2d_asm_Nx) is an instantaneous 2-dimensional hourly data collection in Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2). This collection consists of assimilations of meteorological diagnostic parameters at the single levels, such as temperature at 2-meter and 10-meter; wind components at 2-meter, 10-meter, and 50-meter; surface pressure, and total precipitable water. The timestamp of a data field is on each hour starting from 00:00 UTC, e.g.: 00:00, 01:00, … , 23:00 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).
Version Description
The GEOS-5 model version used for processing MERRA-2
Product Summary
Platforms
MERRA-2
Instruments
NOT APPLICABLE
Projects
MERRA-2
Spatial Extent
N: 90S: -90E: 180W: -180
Spatial Resolution
0.625 Decimal Degrees x 0.5 Decimal Degrees
Location
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
1980-01-01 to Present
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
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.
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Global Modeling and Assimilation Office, & Pawson, S. (2015). MERRA-2 inst1_2d_asm_Nx: 2d,3-Hourly,Instantaneous,Single-Level,Assimilation,Single-Level Diagnostics V5.12.4 [Dataset]. NASA Goddard Earth Sciences Data and Information Services Center. https://doi.org/10.5067/3Z173KIE2TPD Date Accessed: 2026-06-11
Global Modeling and Assimilation Office, & Pawson, S. (2015). MERRA-2 inst1_2d_asm_Nx: 2d,3-Hourly,Instantaneous,Single-Level,Assimilation,Single-Level Diagnostics V5.12.4 [Dataset]. NASA Goddard Earth Sciences Data and Information Services Center. https://doi.org/10.5067/3Z173KIE2TPD Date Accessed: 2026-06-11
Global Modeling and Assimilation Office, and Steven Pawson. “MERRA-2 inst1_2d_asm_Nx: 2d,3-Hourly,Instantaneous,Single-Level,Assimilation,Single-Level Diagnostics V5.12.4.” NASA Goddard Earth Sciences Data and Information Services Center, 2015, https://doi.org/10.5067/3Z173KIE2TPD. Date Accessed: 2026-06-11