1. SAG Ozone Alkis Bais 18-21/2/2015Joint SSC and SAG/ET Chairs Meeting

2. Major Achievements ACSO activity completed – recommended adoption of ozone absorption cross sections measured by U of Bremen for ground based total ozone retrieval Continuing support of Dobson and Brewers with regular calibration campaigns Establishment of new stations with unused Dobson (Brewer?) spectrophotometers in areas with poor ground-based coverage (South Africa, Ukraine, Armenia, Uganda, Siberia, possibly Zambia) Links established with EUBREWNET COST Action and EURAMET-ATMOZ Better agreement has been achieved between satellite and ground-based total ozone measurements – IGACO-Ozone/UV, ESA ozone CCI Homogenization of ozonesonde records (O3S-DQA part of SI2N- Assessment) – Guidelines for reprocessing O3S data – Reduction of uncertainty to 5-10% – Quantification of uncertainties for each sounding 18-21/2/2015Joint SSC and SAG/ET Chairs Meeting

3. Visions/developments (ozone column) Improving the accuracy of total ozone retrieval algorithms – implement the recommended ozone cross sections (U of Bremen - Serdyuchenko 2012) for Brewer and Dobson spectrophotometers – test and possibly implement ozone profile weighted temperature dependent cross sections – exploit new developments in instrument characterization Evaluation of total ozone data from array/ccd spectrographs (e.g., SAOZ, Pandora, Phaethon, etc.) – expanding geographical coverage of the GB network – possible replacement of unserviceable Dobson/Brewer spectrophotometers Modernization of the ozone database (WOUDC) and user web interface – Beta version launched already – NRT database for Brewer spectrophotometer data (O 3, AOD, UV) is under development (EUBREWNET) – Declining data submission rates to WOUDC Integrate results from EUBREWNET COST Action and EURAMET ATMOZ project in the ozone observing system 18-21/2/2015Joint SSC and SAG/ET Chairs Meeting

4. Visions/developments (ozone profiles) Improving the retrieval algorithm for routine data processing of Umkehr data from Dobson and Brewer spectrophotometers – new multi-wavelength software in preparation – Improvement of archiving raw data Establishment of a long-term data quality control programme for ozonesondes – document adequately important properties and quality of O3S data Implementation of guidelines for estimation of uncertainties in ozone profiles – Joined activity with GCOS Reference Upper Air Network (GRUAN) Standardize intercomparisons of ozonesonde data with aircraft data from MOZAIC/IAGOS Integration of profile data from lidar and microwave instruments 18-21/2/2015Joint SSC and SAG/ET Chairs Meeting