Ozone profile retrievals from the Ozone Monitoring Instrument

摘要

Ozone profiles from the surface to about 60 km are retrieved from OzoneMonitoring Instrument (OMI) ultraviolet radiances using the optimalestimation technique. OMI provides daily ozone profiles for the entiresunlit portion of the earth at a horizontal resolution of 13 km×48 kmfor the nadir position. The retrieved profiles have sufficient accuracyin the troposphere to see ozone perturbations caused by convection, biomassburning and anthropogenic pollution, and to track their spatiotemporaltransport. However, to achieve such accuracy it has been necessary tocalibrate OMI radiances carefully (using two days of Aura/Microwave LimbSounder data taken in the tropics). The retrieved profiles contain ~6–7 degrees of freedom for signal, with 5–7 in the stratosphere and 0–1.5in the troposphere. Vertical resolution varies from 7–11 km in thestratosphere to 10–14 km in the troposphere. Retrieval precisions range from1% in the middle stratosphere to 10% in the lower stratosphere andtroposphere. Solution errors (i.e., root sum square of precisions andsmoothing errors) vary from 1–6% in the middle stratosphere to 6–35%in the troposphere, and are dominated by smoothing errors. Total,stratospheric, and tropospheric ozone columns can be retrieved with solutionerrors typically in the few Dobson unit range at solar zenith angles lessthan 80°.