Ozone Monitoring Instrument geolocation verification

Verification of the geolocation assigned to individual ground pixels as measured by the Ozone Monitoring Instrument (OMI) aboard the NASA EOS‐Aura satellite was performed by comparing geophysical Earth surface details as observed in OMI false color images with the high‐resolution continental outline vector map as provided by the Interactive Data Language (IDL) software tool from ITT Visual Information Solutions. The OMI false color images are generated from the OMI visible channel by integration over 20‐nm‐wide spectral bands of the Earth radiance intensity around 484 nm, 420 nm, and 360 nm wavelength per ground pixel. Proportional to the integrated intensity, we assign color values composed of CRT standard red, green, and blue to the OMI ground pixels. Earth surface details studied are mostly high‐contrast coast lines where arid land or desert meets deep blue ocean. The IDL high‐resolution vector map is based on the 1993 CIA World Database II Map with a 1‐km accuracy. Our results indicate that the average OMI geolocation offset over the years 2005–2006 is 0.79 km in latitude and 0.29 km in longitude, with a standard deviation of 1.64 km in latitude and 2.04 km in longitude, respectively. Relative to the OMI nadir pixel size, one obtains mean displacements of ∼6.1% in latitude and ∼1.2% in longitude, with standard deviations of 12.6% and 7.9%, respectively. We conclude that the geolocation assigned to individual OMI ground pixels is sufficiently accurate to support scientific studies of atmospheric features as observed in OMI level 2 satellite data products, such as air quality issues on urban scales or volcanic eruptions and its plumes, that occur on spatial scales comparable to or smaller than OMI nadir pixels.