Earth Data School
About
Full catalog/OMHCHOd
OMHCHOd·v003·dataset

Formaldehyde in the air, mapped daily (Aura OMI)

OMI/Aura Formaldehyde (HCHO) Total Column Daily L3 Weighted Mean Global 0.1deg Lat/Lon Grid V003 (OMHCHOd) at GES DISC
atmosphere NASA GES_DISC Level 3 active
In plain English

What it measures. Daily global maps of formaldehyde in the air, given as the total amount in a vertical column over each fine 0.1-degree grid cell, averaged from cloud-free measurements.

How it's made. Produced from the OMI instrument on NASA's Aura satellite by combining roughly 15 orbits per day into a daily weighted-average map, with extra fields like cloud and albedo info included.

How & where you'd use it. Formaldehyde is a marker of certain pollution and natural plant emissions, so this helps study air quality and the chemistry that forms ozone and smog. The included weights let users combine days to reduce noise.

What's measured

ATMOSPHERE › ATMOSPHERIC CHEMISTRY › CARBON AND HYDROCARBON COMPOUNDS › FORMALDEHYDE

Coverage & cadence

  • Time span2004-10-01 → ongoing
  • Measured byAura (OMI)
  • Processing levelLevel 3
  • Spatial extent-180, -90, 180, 90
  • 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

The OMI/Aura Formaldehyde (HCHO) Total Column Daily L3 Weighted Mean Global 0.1deg Lat/Lon Grid (OMHCHOd). The formaldehyde values in each file are the average for 0.1 x 0.1 degree grid cell of cloud-screened total HCHO columns for a single day. Other variables included in the files are the weight of each grid cell, the standard error of column averages, mean albedo, mean cloud fraction, mean cloud pressure, and surface height. The weight information is useful for combining data from several files and reducing the noise of the retrievals by co-adding in the temporal or spatial dimensions. The OMHCHOd files are in the netCDF4 format which is compatible with most HDF5 readers and tools. Each file contains daily data from approximately 15 orbits. The maximum file size for the OMHCHOd data product is about 80 Mbytes.

Get the data

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

results = earthaccess.search_data(
    short_name="OMHCHOd",
    version="003",
    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.