This dataset contains daily global gridded (0.25 x 0.25) Nitrogen Dioxide Product (OMNO2d) concentrations. Nitrogen dioxide (NO2) is produced in the troposphere, where it is a precursor to ozone production, and plays a key role in ozone chemistry in the stratosphere; it is also an indicator of poor air quality. These data, which are derived from the Ozone Monitoring Instrument (OMI) aboard NASA’s Earth Observing System (EOS)’s Aura satellite, contain total column NO2 and total tropospheric column NO2, for all atmospheric conditions, and for sky conditions where cloud fraction is less than 30 percent. Data collection began in 2004 and is ongoing.

The OMNO2d data are stored in version 5 EOS Hierarchical Data Format (HDF-EOS). Each file contains data from the day lit portion of the orbit (~14 orbits). The average file size for the OMNO2d data product is about 12 megabytes.