Earth Data School
About
Full catalog/UARML3AT
UARML3AT·v005·dataset

Profiles of upper-atmosphere gases (UARS microwave sounder)

UARS Microwave Limb Sounder (MLS) Level 3AT V005 (UARML3AT) at GES DISC
atmosphere NASA GES_DISC Level 3
In plain English

What it measures. Daily vertical profiles through the upper atmosphere of temperature, height, and the amounts of several gases—including ozone, water vapor, and chlorine monoxide—from about 10 to 85 km up.

How it's made. Derived from the Microwave Limb Sounder on NASA's UARS satellite, which looked sideways across the atmosphere's edge and read microwave energy from these gases, processed onto standard latitude and pressure layers.

How & where you'd use it. A historical record for studying the stratosphere and mesosphere, especially the link between chlorine compounds and ozone destruction—key to understanding the ozone layer.

What's measured

ATMOSPHERE › ALTITUDE › GEOPOTENTIAL HEIGHTATMOSPHERE › ATMOSPHERIC CHEMISTRY › CARBON AND HYDROCARBON COMPOUNDS › METHYL CYANIDEATMOSPHERE › ATMOSPHERIC CHEMISTRY › HALOCARBONS AND HALOGENS › CHLORINE MONOXIDEATMOSPHERE › ATMOSPHERIC CHEMISTRY › NITROGEN COMPOUNDS › ATMOSPHERIC NITRIC ACIDATMOSPHERE › ATMOSPHERIC CHEMISTRY › OXYGEN COMPOUNDS › ATMOSPHERIC OZONEATMOSPHERE › ATMOSPHERIC CHEMISTRY › SULFUR COMPOUNDS › SULFUR DIOXIDEATMOSPHERE › ATMOSPHERIC WATER VAPOR › WATER VAPOR PROFILES › WATER VAPOR MIXING RATIO PROFILESATMOSPHERE › ATMOSPHERIC WATER VAPOR › WATER VAPOR INDICATORS › HUMIDITY › RELATIVE HUMIDITYATMOSPHERE › ATMOSPHERIC TEMPERATURE › UPPER AIR TEMPERATURE

Coverage & cadence

  • Time span1991-09-18 → 1999-07-28
  • Measured byUARS (MLS)
  • Processing levelLevel 3
  • Spatial extent-180, -80, 180, 80
  • 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 Microwave Limb Sounder (MLS) Level 3AT data product consists of daily, 4 degree increment latitude-ordered vertical profiles of temperature, geopotential height, concentrations of O3, H2O, CH3CN, ClO, HNO3, and SO2, as well as upper tropospheric humidity (UTH). The insrument measures in the microwave spectral region at frequencies of 63, 183 and 205 GHz. MLS was flown on NASA's Upper Atmosphere Research Satellite (UARS) and designed to measure the chemical composition of the stratosphere and mesosphere, relationship between chlorine monoxide and ozone destruction. Limb measurements were made in the altitude range between 10 and 85 km at about 2.5 km resolution. Data were collected between latitude 34S and 80N and 80S and 34N, alternating each satellite yaw cycle of about 36 days. The MLS Level 3AT data were processed with the version 5 algorithm, except H2O and HNO3 which are version 6, and SO2 and UTH which remained version 4. Note: H2O and O3 at 183 GHz data are available only through April 15, 1993 when the 183 GHz radiometer failed. The MLS level 3AT product consists of 10 granules per day. A data granule is one MLS species or subtype per day. Data are on the UARS standard pressure levels (in mbars) given by: P(i) = 1000 * 10**(-i/6) for i = 0, 1, 2, ... Each of the 10 MLS granules is accompanied by an additional parameter file, designated as level 3TP. The parameter file, contains the additional ancillary and quality information, as well as total column amounts not found in the 3AT files. The data files are available in a binary record oriented format.

Get the data

uarml3at_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="UARML3AT",
    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.