Earth Data School
About
Full catalog/ML2H2O
ML2H2O·v005·dataset

Water vapor high in the atmosphere (Aura MLS)

MLS/Aura Level 2 Water Vapor (H2O) Mixing Ratio V005 (ML2H2O) at GES DISC
atmosphere NASA GES_DISC Level 2 active
In plain English

What it measures. Profiles of how much water vapor is present high in the atmosphere, from the lower stratosphere up to very thin air, measured along the satellite's orbit nearly worldwide.

How it's made. Comes from the Microwave Limb Sounder on NASA's Aura satellite, which looks sideways at the atmosphere's edge and reads microwave signals (mainly at 190 GHz) to infer water vapor at different heights.

How & where you'd use it. Used to study upper-atmosphere chemistry and climate, including the movement of water vapor in the stratosphere, which matters for ozone and the planet's energy balance.

What's measured

ATMOSPHERE › ATMOSPHERIC WATER VAPOR › WATER VAPOR PROFILES › WATER VAPOR MIXING RATIO PROFILES

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

ML2H2O is the EOS Aura Microwave Limb Sounder (MLS) standard product for water vapor 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 between 316 and 0.00215 hPa, and the vertical resolution is about 1.5 km at 316 hPa increasing to 3.5 km to 4.64 hPa, and degrades to 15 km above 0.1 hPa. Users of the ML2H2O data product should read section 3.9 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

ml2h2o_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="ML2H2O",
    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.