Total column ozone in New Zealand and in the UK in the 1950s

Abstract

Total column ozone measurements reach back almost a century. Historical column ozone data are important not only for obtaining a long-term perspective of changes of the ozone layer but arguably also as diagnostics of lower-stratospheric or tropopause-level flow in time periods of sparse upper-air observations. With the exception of a few high-quality records such as that from Arosa, Switzerland, ozone science has almost exclusively focused on data since the International Geophysical Year (IGY) in 1957-1958, although earlier series exist. In the early 2000s, we digitised and re-evaluated many pre-IGY series. Here we add a series from Wellington, New Zealand, from 1951 to 1959. We re-evaluated the data from the original observation sheets and performed quality control analysis, and here we present the data. The day-to-day variability can be used to assess the quality of reanalysis products, since the data cover a region and time period with only few upper-air data. Comparison with total column ozone in the reanalyses ERA-PreSAT (which assimilates upper-air data) and 20CRv3 and CERA-20C (which do not assimilate upper-air data) shows high correlations with all three. Although trend quality is doubtful (no calibration information and no intercomparisons are available), combining the record with other available data (including historical data from Australian locations) allows a 70-year perspective of ozone changes over the southern mid-latitudes. The series will be available from the World Ozone and Ultraviolet Data Centre. Finally, we also present a short series from Downham Market, UK, covering November 1950 to October 1951, and publish it with further historical data series that were previously described but not published..