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Full catalog/ML2HNO3
ML2HNO3·v005·dataset

Nitric acid high in the atmosphere (Aura)

MLS/Aura Level 2 Nitric Acid (HNO3) Mixing Ratio V005 (ML2HNO3) at GES DISC
atmosphere NASA GES_DISC Level 2 active
In plain English

What it measures. Tracks how much nitric acid is present at different heights in the atmosphere, given as a profile from the lower stratosphere upward. Nitric acid plays a role in the chemistry that controls ozone.

How it's made. Derived from microwave signals the Aura satellite's Microwave Limb Sounder picks up by looking sideways through the edge of the atmosphere, turned into vertical profiles.

How & where you'd use it. Used by atmospheric scientists studying ozone chemistry and how the stratosphere behaves; it is a specialist research product rather than something for everyday use.

What's measured

ATMOSPHERE › ATMOSPHERIC CHEMISTRY › NITROGEN COMPOUNDS › ATMOSPHERIC NITRIC ACID

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

ML2HNO3 is the EOS Aura Microwave Limb Sounder (MLS) standard product for nitric acid derived from radiances measured by the 240 GHz radiometer at and below 10 hPa, and from the 190 GHz radiometer above 10 hPa. The data version is 5.0. Data coverage is from August 8, 2004 to current. 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 215 to 1.47 hPa (1.0 hPa under enhanced conditions), and the vertical resolution is between about 3 and 5 km. Users of the ML2HNO3 data product should read section 3.12 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

ml2hno3_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="ML2HNO3",
    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.