Research project P4S/25/ROMA (Research action P4S)
For a century, the total ozone column (TOC) has been measured using ground-based instruments, by Dobson and Brewer spectrophotometers. These instruments are now the World Meteorological Organization (WMO) standards for ozone monitoring. Dobson and Brewer measurements had a tremendous role in our understanding of stratospheric chemistry, e.g. for the discovery of the ozone hole over Antarctica and for the validation of atmospheric satellite data. The future evolution of stratospheric ozone remains uncertain and ground-based ozone reference measurements will continue to be essential for evaluating the impacts of the Montreal Protocol, climate change, and related shifts in atmospheric chemistry, such as those caused by major wildfires. However, the Dobson instrument is no longer produced and the manufacturer of the Brewer instrument announced in October 2024 the stop of production and servicing of the instrument. Therefore, the ozone community needs to find new reference instruments for the TOC ground-based measurements.
The new TOC reference instruments must match the precision of the Brewer and Dobson, achieving the WMO target accuracy of 1%. These instruments should also offer long-term stability and be robust enough to withstand varying environmental conditions across the globe. Currently, two candidates are being evaluated by the scientific community: Pandora and BTS. To finalize the selection of a suitable successor to the Brewer, the ozone community requires dedicated intercomparison campaigns in polar regions, as well as further investigations into the long-term stability of the new instruments. The Brewer, BTS and Pandora instrments have not yet been intercompared all three together in Antarctica. The Belgian Princess Elisabeth Station (PES) therefore provides an ideally suited platform for operating and comparing these instruments.
The specific objectives of the ROMA project are as follows:
- Operate a RMI Brewer ozone spectrophotometer, which is already installed at PES, year-round. Until now, the Brewer has only been operated during austral summer when the station was inhabited.
- Move a BIRA-IASB Pandora instrument (previously sited in Uccle, BE) at PES, for year-round ozone monitoring after appropriate instrumental adaptation. In addition to ozone, the Pandora will measure a set of key ozone-related chemical species (NO2, OClO, BrO, and NO3).
- Acquire on project costs a BTS spectrometer and operate it at PES year-round.
- Evaluate whether Pandora and BTS systems fulfill requirements to serve as the future WMO total ozone column (TOC) standard. This activity will use both historic data at Uccle and those acquired during the project at PES.
- Perform systematic comparisons between our ground-based TOC measurements and data from existing (TROPOMI, GOME2) and future satellite sensors to be launched during the project (S5, Altius). In addition, the acquired TOC data set will be compared to existing reanalysis data sets.
- Assess whether NO2, OClO, and BrO column measurements derived from Pandora data can further contribute to satellite validation in Antarctica
