The main work in SHARP-OCF has been the generation of merged ozone satellite data sets, a study on the interannual variability of total ozone in connection with the Brewer-Dobson, investigations on fingerprints of observed ozone recovery, the analysis of stratospheric bromine from SCIAMACHY, balloon- and aircraft borne observations, studies on transport of iodine to the tropical tropopause layer and into the stratosphere, chemistry-transport modeling of transport of brominated very short-lived substances (VSLS) into the stratosphere, a CCM simulation with emissions of brominated VSLS, and the prediction of future ozone using CCMs. The activities in SHARP-OCF provided a broad collaboration between modelers, both using CCMs and CTMs, and observers/data providers permitting a confrontation of models with observations and vice versa that provided valuable insight and a better understanding of underlying processes governing changes in stratospheric ozone in the past and future.

A merged total ozone data set has been created from the European sensors GOME, SCIAMACHY, and GOME-2 now spanning a harmonised sixteen year data record. This dataset contributed to the current WMO assessment (WMO, 2011). The generation of the merged ozone profile data record from nadir observations of the same instruments is still ongoing due to the late hiring of the first PhD candidate (UBR). Using the merged total ozone data record, interannual variability in spring ozone has been correlated to the strength of the Brewer-Dobson-Circulation and the very compact linear relationship found here was also well reproduced by two transient CCM model simulations (Weber et al., 2011). Both models and observations indicate signs of ozone recovery from the shifts in this linear relationship. Transport studies on how brominated VSLS, believed to significantly contribute to the total stratospheric bromine budget, can reach the TTL have been carried out with the Bremen 3D CTM, in which convective transport has been explicitly treated (Aschmann et al., 2011). The second Ph.D. student (UBR), hired in January 2011, investigated trends in BrO derived from SCIAMACHY limb measurements. From the nearly decade of SCIAMACHY data available (Rozanov et al., 2011), he inferred a trend in the lowermost stratosphere (15-27 km) of about -1 to -2% per decade in each hemisphere, which is in good agreement with results reported in WMO (2011). Further studies on reducing the uncertainties in these trends are still ongoing. Updated trends in the total bromine were derived from UH using more recent balloon data that confirm the rebound of stratospheric bromine as a result of the phasing out of ozone depleting substance emissions. These results contributed to WMO (2011). Direct measurements (IO and OIO) from the UH balloon campaigns (Butz et al., 2009) suggest negligible iodine amounts in the TTL, however, more recent observations seem to indicate that substantial iodine could be transported to the TTL and stratosphere via organic substances attached to aerosols.

Two transient simulations from 1960 to 2100 with the EMAC CCM have been performed at FUB within the CCMVal initiative (SPARC CCMVAL, 2010) and results of these simulations contributed to the WMO Scientific Assessment of Ozone Depletion: 2010 (2011). Output of these simulations contributed to the assessments of the Antarctic ozone hole (Austin et al., 2010) and future ozone recovery (Eyring et al., 2010). In a close collaboration with the SHARP partners KIT and MPI-C, a first transient simulation with emissions of brominated very short-lived substances (VSLS) has been performed to investigate the impact of VSLS on ozone under a changing climate.