First reprocessing of southern hemisphere ADditional OZonesondes profile records: 3. Uncertainty in ozone profile and total column

Reprocessed ozonesonde data from eight SHADOZ (Southern Hemisphere ADditional OZonesondes) sites have been used to derive the first analysis of uncertainty estimates for both profile and total column ozone (TCO). The ozone uncertainty is a composite of the uncertainties of the individual terms in the ozone partial pressure (P-O3) equation, those being the ozone sensor current, background current, internal pump temperature, pump efficiency factors, conversion efficiency, and flow rate. Overall, P-O3 uncertainties (P-O3) are within 15% and peak around the tropopause (153km) where ozone is a minimum and P-O3 approaches the measured signal. The uncertainty in the background and sensor currents dominates the overall P-O3 in the troposphere including the tropopause region, while the uncertainties in the conversion efficiency and flow rate dominate in the stratosphere. Seasonally, P-O3 is generally a maximum in the March-May, with the exception of SHADOZ sites in Asia, for which the highest P-O3 occurs in September-February. As a first approach, we calculate sonde TCO uncertainty (TCO) by integrating the profile P-O3 and adding the ozone residual uncertainty, derived from the McPeters and Labow (2012, doi:10.1029/2011JD017006) 1 sigma ozone mixing ratios. Overall, TCO are within 15 Dobson units (DU), representing similar to 5-6% of the TCO. Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument (TOMS and OMI) satellite overpasses are generally within the sonde TCO. However, there is a discontinuity between TOMS v8.6 (1998 to September 2004) and OMI (October 2004-2016) TCO on the order of 10DU that accounts for the significant 16DU overall difference observed between sonde and TOMS. By comparison, the sonde-OMI absolute difference for the eight stations is only similar to 4DU.