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’s Ozone Monitoring Instrument (OMI) is a primary
quality indicator. Comparisons of sonde ozone with Aura’s Microwave Limb
Sounder (MLS) are used to assess the stability of stratospheric ozone.
This paper provides a comprehensive examination of global ozonesonde
network data stability and accuracy since 2004. Comparisons with Aura
OMI TCO averaged across the network of 60 stations are stable within
about +/-2% over the past 18 years. Sonde TCO has similar stability
compared to three other TCO satellite instruments, and the stratospheric
ozone measurements average to within +/-5% of MLS from 50 to 10 hPa.
Thus, sonde data are reliable for trends, but with a caveat applied for
a subset of stations in the tropics and subtropics for which a sudden
post-2013 TCO “dropoff” of ~3-4% was reported
previously (Stauffer et al., 2020). The dropoff is associated with only
one of two major ECC instrument types. A detailed examination of ECC
serial numbers pinpoints the timing of the dropoff. However, we find
that overall, ozonesonde data are stable and accurate compared to
independent measurements over the past two decades.