Abstract
Abstract. The combined record of total and profile ozone measurements from the solar backscatter ultraviolet (SBUV) and SBUV/2 series of instruments, known as the SBUV Merged Ozone Data (MOD) product, constitutes the longest satellite-based ozone time series from a single instrument type and as such plays a key role in ozone trend analyses.Following the approach documented in Frith et al. (2014) to analyze the merging uncertainties in the MOD total ozone record, we use Monte Carlo simulations to estimate the potential for uncertainties in the calibration and drift of individual instruments in the profile ozone merged data set. We focus our discussion on the trends and associated merging uncertainty since 2001 in an effort to verify the start of ozone recovery as predicted by chemistry climate models. We find that merging uncertainty dominates the overall estimated uncertainty when considering only the 15 years of data since 2001. We derive trends versus pressure level for the MOD data set that are positive in the upper stratosphere as expected for ozone recovery. These trends appear to be significant when only statistical uncertainties are included but become not significant at the 2σ level when instrument uncertainties are accounted for. However, when we use the entire data set from 1979 through 2015 and fit to the EESC (equivalent effective stratospheric chlorine) we find statistically significant fits throughout the upper stratosphere at all latitudes. This implies that the ozone profile data remain consistent with our expectation that chlorine is the dominant ozone forcing term.
Highlights
The solar backscatter ultraviolet (SBUV) series of instruments provides a 40+-year data record of broadly resolved vertical ozone profiles on a global scale
We recently reported on our updated Merged Ozone Data (MOD) record of integrated total column SBUV measurements (Frith et al, 2014)
While this approach minimized differences among instruments, Frith et al (2014) showed that small remaining offsets and drifts between measurements contributed to the uncertainty in the total ozone SBUV MOD record
Summary
The solar backscatter ultraviolet (SBUV) series of instruments provides a 40+-year data record of broadly resolved vertical ozone profiles on a global scale. Ozone was derived for each instrument using the Version 8.6 retrieval algorithm to produce the measurement time series used to create the MOD data set (McPeters et al, 2013) While this approach minimized differences among instruments, Frith et al (2014) showed that small remaining offsets and drifts between measurements contributed to the uncertainty in the total ozone SBUV MOD record. Profile ozone differences among the individual SBUV instrument measurements are larger than was the case for total ozone, but the uncertainty issues are quite similar. We attempt to quantify these uncertainties and model their time dependence using a Monte Carlo approach to estimate their impact on the longterm variability in the ozone profile measurements
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