The Ozone Monitoring Instrument (OMI) was launched on-board the Earth Observing System (EOS) Aura satellite on 15 July 2004 in a polar orbit with an afternoon equator crossing time near 13:30. OMI is a wide-swath, nadir-looking, push-broom imaging spectrometer, measuring Earth radiance and solar irradiance from ultraviolet to visible wavelengths (270–500 nm) with a spectral resolution of about 0.5 nm. The vertical columns of several trace gases are retrieved with better spatial and temporal sampling than previous instruments of its type. In particular, OMI observations of nitrogen dioxide, sulfur dioxide, and formaldehyde have enabled new applications in air quality (e.g. emission estimates) and hazard monitoring (e.g. volcanic cloud detection for aviation safety). Observations of the ozone abundance and estimates of UV radiation at the ground are used to track the effects of the Montreal Protocol. OMI observations of tropospheric ozone and aerosols together with minor trace gases provide global input for climate research.

OMI is one of the four instruments on the Aura platform. Together with the three other instruments – the High Resolution Dynamics Limb Sounder (HIRDLS), the Microwave Limb Sounder (MLS), and the Tropospheric Emission Spectrometer (TES) – Aura has functioned as an integrated platform for atmospheric composition measurements. Aura is part of a constellation of satellites (including the Aqua platform) in similar afternoon orbits known as the A-train. Having many different types of instrumentation in this constellation allows for synergetic uses of the data sets.

In this OMI special issue, we highlight scientific research accomplished with 10 years of OMI atmospheric composition measurements, discuss recent improvements in OMI retrieval algorithms and methodologies to utilize the data, and present the status of various OMI data products.

The Dutch–Finnish OMI instrument is currently operational on the NASA Earth Observing System (EOS) Aura satellite and was developed under the assignment of the Netherlands Space Office (NSO) and Tekes – Finnish Funding Agency for Innovation.