As part of the SPARC Data Initiative, S. Tegtmeier and co-authors present some of the main findings from the comparison of ozone climatologies from satellite limb sounders in a new JGR article. The ozone climatologies cover altitudes from the upper troposphere to the lower mesosphere and are obtained from a host of instruments over the period 1978-2010 (LIMS, SAGE I, SAGE II, UARS-MLS, HALOE, POAM II, POAM III, SMR, OSIRIS, SAGE III, MIPAS, GOMOS, SCIAMACHY, ACE-FTS, ACE-MAESTRO, Aura-MLS, HIRDLS, and SMILES). The inter-comparisons focus on mean biases based on monthly and annual zonal mean fields, on inter-annual variability and on seasonal cycles. Their results indicate that uncertainty in terms of the mean state of ozone is lowest in the tropical middle stratosphere and in the mid-latitude lower and middle stratosphere, where the instrument spread is less than ±5%. Large differences between data sets exist in the tropical lower stratosphere and in the high latitudes, where instrument spread is ±30% and ±15%, respectively. The evaluations provide a very useful guidance tool for choice of reliable data sets for different applications. The full abstract can be found here.