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Full catalog/ML2OH
ML2OH·v005·dataset

Hydroxyl, the air's cleanup molecule (MLS, Aura)

MLS/Aura Level 2 Hydroxyl (OH) Mixing Ratio V005 (ML2OH) at GES DISC
atmosphere NASA GES_DISC Level 2
In plain English

What it measures. Amounts of hydroxyl (OH), a short-lived molecule that acts like the atmosphere's natural cleaning agent, measured at different heights through the upper atmosphere along the satellite's track. Coverage is near-global, mostly from 2004 to 2009.

How it's made. Derived from terahertz radiation measured by the Microwave Limb Sounder aboard NASA's Aura satellite.

How & where you'd use it. Helps scientists study atmospheric chemistry and how the air breaks down pollutants and greenhouse gases.

What's measured

ATMOSPHERE › ATMOSPHERIC CHEMISTRY › HYDROGEN COMPOUNDS › HYDROXYL

Coverage & cadence

  • Time span2004-08-02 → 2014-10-01
  • Measured byAura (MLS)
  • Processing levelLevel 2
  • Spatial extent-180, -82, 180, 82
  • 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

ML2OH is the EOS Aura Microwave Limb Sounder (MLS) standard product for hydroxyl derived from radiances measured by the THz radiometer. The data version is 5.0. Data coverage is continuous from August 8, 2004 to December 12, 2009 when the THz radiometer was placed in standby mode. After this date OH data were collected for about 30 days in August/September of 2011, 2012, 2013 and 2014. Spatial coverage is near-global (-82 degrees to +82 degrees latitude), with each profile spaced 1.5 degrees or ~165 km along the orbit track (roughly 15 orbits per day). The recommended useful vertical range is from 31.6 to 0.00316 hPa, and the vertical resolution is about 3. Users of the ML2OH data product should read section 3.19 of the EOS MLS Level 2 Version 5 Quality Document for more information. The data are stored in the version 5 EOS Hierarchical Data Format (HDF-EOS5), which is based on the version 5 Hierarchical Data Format, or HDF-5. Each file contains two swath objects (profile and column data), each with a set of data and geolocation fields, swath attributes, and metadata.

Get the data

ml2oh_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="ML2OH",
    version="005",
    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.