Empirical assessment of errors in total ozone measurements with different instruments and methods

Abstract

Knowledge of measurement errors is one of the most important issues for assessing the quality of experimental data. In this paper, we compared various methods and instruments for measuring the total ozone content (TOC) near St. Petersburg in the period from 2009 to 2015. We considered the TOC datasets of ground-based measurements at Voyeykovo (Dobson spectrophotometer and M-124 ozonometer) and Peterhof (Bruker 125HR spectrometer), as well as OMI and IASI satellite measurements. To assess the errors intrinsic to each of these instruments three ensembles of the TOC measurements were formed containing different numbers of comparisons and based on different selection criteria. At the first stage, we determined the means and standard deviations between the ensembles of the TOC measurements. Then, assuming a horizontally homogeneous and stationary ozone field, the random and systematic errors of individual methods were evaluated. The average random errors of the TOC measurements for all tree ensembles were 2.9 ± 0.5%, 2.8 ± 0.7%, 1.2 ± 0.2%, and 1.4 ± 0.1% for IASI, M-124, OMI, and Bruker 125HR, respectively. The systematic error of the standard Dobson measurements is–1.7% and–2.1% for OMI and IASI, respectively, and amounts to + 0.5% and + 2.1% for M-124 and Bruker 125HR, respectively. The OMI and Bruker 125HR TOC measurement errors are most resistant to atmospheric conditions, whereas errors in IASI and M-124 TOC measurements depend to a large extent on the state of the atmosphere.