First Reprocessing of Southern Hemisphere ADditional OZonesondes Profile Records: 3. Uncertainty in Ozone Profile and Total Column
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Witte, Jacquelyn C., Anne M. Thompson, Herman G. J. Smit, Holger Vömel, Françoise Posny, and Rene Stübi. “First Reprocessing of Southern Hemisphere ADditional OZonesondes Profile Records: 3. Uncertainty in Ozone Profile and Total Column.” Journal of Geophysical Research: Atmospheres 123, no. 6 (2018): 3243–68. https://doi.org/10.1002/2017JD027791.
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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract
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 (Pₒ₃) equation, those being the ozone sensor current, background current, internal pump temperature, pump efficiency factors, conversion efficiency, and flow rate. Overall, Pₒ₃ uncertainties (ΔPₒ₃) are within 15% and peak around the tropopause (15 ± 3 km) where ozone is a minimum and ΔPₒ₃ approaches the measured signal. The uncertainty in the background and sensor currents dominates the overall ΔPₒ₃ in the troposphere including the tropopause region, while the uncertainties in the conversion efficiency and flow rate dominate in the stratosphere. Seasonally, ΔPₒ₃ is generally a maximum in the March–May, with the exception of SHADOZ sites in Asia, for which the highest ΔPₒ₃ occurs in September–February. As a first approach, we calculate sonde TCO uncertainty (ΔTCO) by integrating the profile ΔPₒ₃ and adding the ozone residual uncertainty, derived from the McPeters and Labow (2012, doi:10.1029/2011JD017006) 1σ ozone mixing ratios. Overall, ΔTCO are within ±15 Dobson units (DU), representing ~5–6% of the TCO. Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument (TOMS and OMI) satellite overpasses are generally within the sonde ΔTCO. However, there is a discontinuity between TOMS v8.6 (1998 to September 2004) and OMI (October 2004–2016) TCO on the order of 10 DU that accounts for the significant 16 DU overall difference observed between sonde and TOMS. By comparison, the sonde-OMI absolute difference for the eight stations is only 4 DU.