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(sub O3)) equation, those being the ozone sensor current, background current, internal pump temperature, pump efficiency factors, conversion efficiency, and flow-rate. Overall, P(sub O3) uncertainties (Delta P(sub O3)) are within 15% and peak around the tropopause (15+/-3km) where ozone is a minimum and Delta P(sub O3) approaches the measured signal. The uncertainty in the background and sensor currents dominate the overall Delta P(sub O3) in the troposphere including the tropopause region, while the uncertainties in the conversion efficiency and flow-rate dominate in the stratosphere. Seasonally, Delta P(sub O3) is generally a maximum in the March-May, with the exception of SHADOZ sites in Asia, for which the highest Delta P(sub O3) occurs in September-February. As a first approach, we calculate sonde TCO uncertainty (Delta TCO) by integrating the profile Delta P(sub O3) and adding the ozone residual uncertainty, derived from the McPeters and Labow [2012] 1-σ ozone mixing ratios. Overall, Delta TCO are within +/-15 DU, representing approximately 5-6% of the TCO. TOMS and OMI satellite overpasses are generally within the sonde Delta TCO. However, there is a discontinuity between TOMS v8.6 (1998-2004/09) and OMI (2004/10-2016) 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 approximately 4DU.
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