Tropospheric Ozone Profile Retrievals Combining TIR, UV And Visible Spectra

We present ozone profile data from the RAL ozone profile algorithm, optimised for sensitivity to tropospheric and lower tropospheric ozone. The RAL ozone profile algorithm has been selected as the prototype nadir processor to produce a climate quality dataset for community use from GOME, SCIAMACHY, OMI and GOME-2A/B as part of the ESA Climate Change Initiative. We present time-series’ of data as compared to ozonesondes and extensive comparison with chemistry transport, air quality models and MACC-II.

The RAL algorithm additionally combines measurements in the UV and IR, from GOME-2 and IASI aboard MetOp. The jointly retrieved product exploits the complementary vertical sensitivity of the two instruments, particularly in the troposphere.

It can be shown with retrieval simulations that use of visible spectra could significantly add information about near-surface ozone to conventional UV ozone profile retrievals – particularly over land – which has implications for air quality monitoring. The information potentially obtained from the Chappuis ozone band is significant and essentially unique - no other passive technique can provide comparable information on near-surface ozone. However, it has remained a challenge to demonstrate the potential benefits with real measurements. We report our progress on a technique to combine use of UV and visible spectra from the Chappuis ozone band to enhance the sensitivity of the retrievals to near-surface ozone, and evaluate its potential with regard to both existing and future satellite instruments.