Reconstructed weather at all altitudes (MERRA-2, daily cycle)
What it measures. Reconstructed weather conditions throughout the atmosphere at 42 altitude levels, including temperature, winds, water vapor, and ozone, shown as a typical daily cycle in three-hour steps.
How it's made. Generated by MERRA-2, a NASA reanalysis system that blends decades of satellite and other observations with a weather model to produce a consistent, gap-free record from 1980 onward.
How & where you'd use it. A go-to resource for studying past weather and climate patterns, providing complete atmospheric data even where direct measurements were never taken.
What's measured
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
M2IUNPASM (or instU_3d_asm_Np) is an instantaneous 3-dimensional monthly diurnal means data collection in Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2). This collection consists of assimilations of meteorological parameters at 42 pressure levels, such as temperature, wind components, vertical pressure velocity, water vapor, ozone mass mixing ratio, and layer height. The data collection is the monthly mean of data fields every three hours starting from 00:00 UTC, e.g.: 00:00, 03:00, … , 21:00 UTC. The information on the pressure levels can be found in the section 4.2 of the MERRA-2 File Specification document. 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
import earthaccess
earthaccess.login(strategy="netrc") # free Earthdata Login
results = earthaccess.search_data(
short_name="M2IUNPASM",
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_DISCBrowsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package. Official links
- How to read and plot the data. VIEW RELATED INFORMATION
- Access the data via HTTPS. GET DATA
- Use the Earthdata Search to find and retrieve data sets across multiple data centers. GET DATA
- Access the data via the OPeNDAP protocol. USE SERVICE API
- MERRA-2 File Specification Document VIEW RELATED INFORMATION
- README Document VIEW RELATED INFORMATION
- MERRA-2 Data Access – Quick Start Guide VIEW RELATED INFORMATION
- Records of MERRA-2 Data Reprocessing and Service Changes VIEW RELATED INFORMATION