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Full catalog/ML2HCN
ML2HCN·v005·dataset

Hydrogen cyanide gas high in the atmosphere (Aura)

MLS/Aura Level 2 Hydrogen Cyanide (HCN) Mixing Ratio V005 (ML2HCN) at GES DISC
atmosphere NASA GES_DISC Level 2 active
In plain English

What it measures. The amount of hydrogen cyanide gas high in the atmosphere, given as vertical profiles at different altitudes across most of the globe.

How it's made. Measured by the Microwave Limb Sounder on NASA's Aura satellite, mainly from its 190 GHz radiometer, which senses gases along the edge of the atmosphere.

How & where you'd use it. Hydrogen cyanide is a marker of biomass burning, so this helps scientists trace smoke from large fires and study how it moves through the upper atmosphere.

What's measured

ATMOSPHERE › ATMOSPHERIC CHEMISTRY › CARBON AND HYDROCARBON COMPOUNDS › HYDROGEN CYANIDE

Coverage & cadence

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

ML2HCN is the EOS Aura Microwave Limb Sounder (MLS) standard product for hydrogen cyanide derived from radiances measured primarily by the 190 GHz radiometer. The data version is 5.0. 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 21.5 to 0.1 hPa, and the vertical resolution is between 8 and 12 km. Users of the ML2HCN data product should read section 3.11 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

ml2hcn_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="ML2HCN",
    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.