Earth Data School
About
Full catalog/GMAO_M2SCREAM_INST3_CHEM
GMAO_M2SCREAM_INST3_CHEM·v1·dataset

Modeled air chemistry stacked by altitude, every 3 hours (MERRA-2)

M2-SCREAM: 3d,3-Hourly,Instantaneous,Model-Level,Assimilation,Assimilated Constituent Fields,Replayed MERRA-2 Meteorological Fields
atmosphere NASA GES_DISC Level 4
In plain English

What it measures. A modeled, three-dimensional picture of the chemistry of the upper atmosphere: ozone, water vapor, and several trace gases like hydrochloric acid and nitric acid, stacked by altitude and updated every three hours.

How it's made. Created by blending satellite measurements from Aura's MLS and OMI instruments into NASA's GEOS computer model, which fills in the gaps to give a complete global picture (a 'reanalysis').

How & where you'd use it. Helps scientists study the stratosphere's chemistry and ozone layer, and provides consistent global fields for research where direct observations are sparse.

What's measured

ATMOSPHERE › ATMOSPHERIC CHEMISTRY › TRACE GASES/TRACE SPECIES

Coverage & cadence

  • Time span2004-09-01 → 2024-12-31
  • Measured byOBSERVATION BASED (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

The MERRA-2 Stratospheric Composition Reanalysis of Aura MLS (M2-SCREAM) products produced at NASA’s Global Modeling and Assimilation Office (GMAO) are generated by assimilating MLS and OMI retrievals into the GEOS Constituent Data Assimilation System (CoDAS) driven by meteorological fields from MERRA-2. M2-SCREAM assimilates hydrochloric acid (HCl), nitric acid (HNO3), stratospheric water vapor (H2O), nitrous oxide (N2O) and ozone with a system equipped with a version of the GEOS general circulation model and a stratospheric chemistry model, StratChem. Assimilated fields are provided globally at 0.5° by 0.625° resolution at three-hourly frequencies from 2004/09/01 to 2024/09/30. Assimilation uncertainties for each of the assimilated constituents are calculated from the CoDAS statistical output (Wargan et al., 2022) and provided as global full-resolution three-dimensional monthly files. Data product updates in March 2024, as a result of Aura MLS “duty cycle” of 190-GHz measurements, include reduced availability of H2O, N2O and HNO3 retrievals resulting in expected M2-SCREAM data quality degradation. However, preliminary analysis shows that the GEOS CoDAS handles the reduced temporal data coverage well, indicating that the GEOS model accurately propagates information from past observations. Data product updates in June 2024 resulting from MLS version upgrade to v5.0 include discontinuities in assimilated H2O (throughout the stratosphere) and N2O (in the lower stratosphere). To note: MLS water vapor is about 0.5 ppmv lower in v5.0, and the vertical range of assimilated N2O data is 100 hPa, extended down from 68 hPa. GMAO is not aware of discontinuities in HCl, HNO3, and ozone related to the version switch.

Get the data

gmao_m2scream_inst3_chem_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="GMAO_M2SCREAM_INST3_CHEM",
    version="1",
    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.