SCIAMACHY Data Assimilation 2 - final report

The launch of the ESA ENVISAT satellite in March 2002 and near-future missions such as NASA EOS-AURA will largely expand the monitoring of the atmospheric chemical composition from space. Since 1995, GOME on ESA ERS-2 has provided a wealth of information on ozone and reactive trace gases such as NO2. The SCIAMACHY spectrometer on ENVISAT extends the capabilities of GOME, and important additional information on greenhouse gases (including methane) and carbon monoxide is obtained from the channels in the near infrared. Data assim- ilation will play a crucial role in the near future to make optimal use of the huge observational data sets provided by SCIAMACHY and the other new satellite instruments.

In this project, ongoing activities on the assimilation of GOME near-real-time ozone observa- tions in a global tracer-transport model are described. Three-dimensional value-added ozone fields are generated based on the GOME ozone observations. In addition, 5-day ozone forecasts were produced daily during the project. The quality of the analyses and forecasts is thoroughly evaluated. The operational products are provided to the scientific community via the KNMI web site.

The methane modelling capability of the TM3 chemistry-transport model has been further im- proved (model version TMSCIA). A data assimilation scheme has been developed for a methane single-tracer version of TMSCIA. This assimilation model is suitable for high resolution anal- yses of methane data. Tests with simulated data show that the system works well and is ready for the assimilation of SCIAMACHY observations.