An Examination of the Recent Stability of Ozonesonde Global Network Data Date Updated: 30 August 2022

Abstract

The recent Assessment of Standard Operating Procedures for OzoneSondes (ASOPOS 2.0; WMO/GAW Report #268) addressed questions of homogeneity and long-term stability in global electrochemical concentration cell (ECC) ozone sounding network time series.Among its recommendations was adoption of a standard for evaluating data quality in ozonesonde time-series. Total column ozone (TCO) derived from the sondes compared to TCO from Aura’sOzone Monitoring Instrument(OMI)is a primary quality indicator.Comparisons of sonde ozone with Aura’sMicrowave Limb Sounder(MLS)are used to assess the stability of stratospheric ozone. This paper providesa comprehensive examination ofglobal ozonesondenetworkdatastability and accuracy since 2004in light of the sudden post-2013 TCO “dropoff” of ~3-4%that was reported previouslyat select stations(Stauffer et al., 2020). Comparisons with Aura OMI TCO averaged across the networkof 60 stationsare stable within about ±2%over the past 18 years.Sonde TCO has similar stability compared to three other TCO satellite instruments, andthe stratospheric ozone measurementsaverage to within ±5%of MLSfrom 50 to 10hPa. Thus, sonde data are reliable for trends, but with a caveat applied for a subset ofdropoffstations in the tropics and subtropics. The dropoff is associated with only one of two major ECC instrument types. A detailed examination of ECC serial numbers pinpoints the timing of thedropoff. However, we find thatoverall, ozonesonde data are stable and accurate compared to independent measurementsover the past two decades.