Aura: A mission dedicated to the health of Earth's atmosphere


Ozone Monitoring Instrument (OMI)

OMI is a nadir viewing spectrometer that measures solar reflected and backscattered light in a selected range of the ultraviolet and visible spectrum. The instrument’s 2600-km viewing swath is perpendicular to the orbit track, providing complete daily coverage of the sunlit portion of the atmosphere. OMI is Aura’s primary instrument for tracking global ozone change and will continue the high quality column ozone record begun in 1970 by the Backscatter Ultraviolet Detectror (BUV) onboard the Nimbus-4 satellite. Because OMI has a broader wavelength range and better spectral resolution, OMI will also measure column amounts of trace gases important to ozone chemistry and air quality. OMI will map aerosols and estimate ultraviolet radiation reaching the Earth’s surface. OMI’s horizontal resolution is about four times greater than TOMS'.

The Netherlands Agency for Aerospace Programs (NIVR) and the Finnish Meteorological Institute (FMI) contributed the OMI instrument to the Aura mission. The Netherlands companies, Dutch Space and TNO-TPD, together with Finnish companies, Patria, VTT and SSF, built the instrument. OMI contributes to each of Aura’s three science questions.

OMI Contributions to Understanding Stratospheric Ozone

OMI will continue the 34-year satellite ozone record of SBUV and TOMS, mapping global ozone change. OMI data will support Congressionally mandated and international ozone assessments. Using its broad wavelength range and spectral resolution, OMI scientists will be able to resolve the differences among satellite and ground-based ozone measurements. OMI will also measure the atmospheric column of radicals such as nitrogen dioxide (NO2) and chlorine dioxide (OClO).

OMI Contributions to Understanding Air Quality

Tropospheric ozone, nitrogen dioxide, sulfur dioxide, and aerosols are four of the U. S. Environmental Protection Agency’s six criteria pollutants. OMI will map tropospheric columns of sulfur dioxide and aerosols. OMI measurements will be combined with information from MLS and HIRDLS to produce maps of tropospheric ozone and nitrogen dioxide. OMI will also measure the tropospheric ozone precursor formaldehyde. Scientists will use OMI measurements of ozone and cloud cover to derive the amount of ultraviolet radiation (UV) reaching the Earth’s surface. The National Weather Service will use OMI data to forecast high UV index days for public health awareness.

OMI Contributions to Understanding Climate Change

OMI tracks dust, smoke and industrial aerosols in the troposphere. OMI’s UV measurements allow scientists to distinguish reflecting and absorbing aerosols and thus OMI measurements will help improve climate models.

Tropospheric ozone global map This monthly average map was made by subtracting the stratospheric ozone column from TOMS column ozone. The stratospheric column is calculated using UARS MLS measurements. Higher quality tropospheric ozone maps on a daily basis will be produced from OMI and HIRDLS data. (Image courtesy S. Chandra and J. Ziemke, NASA GSFC).

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