Multi-spectral investigation of ozone: Part I. Setup & uncertainty budget. (March 2022) - Janssen, Christof
Highlights: Innovative setup for the simultaneous measurement of ozone in 5 µm and 10 µm regions. Low-pressure measurements on pure ozone traceable to new cross section at 253.65 nm. Comprehensive uncertainty budget with uncertainty of line positions at 3 · 10 − 5 cm − 1 First relative standard uncertainty of line intensities equal or better than 1.1%. High data quality allows to resolve UV-IR discrepancy and to re-evaluate databases. Graphical abstract: Abstract: This is the first in a series of two papers concerned with new accurate high resolution spectroscopic measurements of line positions and intensities of ozone in the 5 µm and 10 µm regions using a commercial Michelson Fourier transform spectrometer. Measurements in both wavelength regions have been made quasi simultaneously using a special H-shaped absorption cell with two parallel absorption paths of different lengths that remained connected during the experiments. Accurate ozone partial pressures were monitored on the shorter of the two paths using UV absorption at the 253.65 nm Hg reference line. In this paper, we report in detail on the experimental setup and provide a comprehensive uncertainty analysis. The spectral analysis and retrieved line parameters are provided in the second paper, which also contains the comparison to the literature data. Line positions have been measured with standard uncertainties of u ( ν 0 ) = 3 · 10 − 5 cm -1 in both spectral regions, mainly in the ν 3 and the ν 1 + ν 3 bands of ozone. Intensities of most of the transitions in the ν 3 band have a relative standard uncertainty of u r ( S ) = 1.1 · 10 − 2 . The uncertainty is slightly smaller for intensities in the ν 1 + ν 3 band at 5 µm. The highly accurate experimental data provide a benchmark for molecular calculations and the 1.1 % line intensity uncertainty will help resolving the discrepancy between UV and IR atmospheric ozone retrievals and correcting current biases in spectroscopic databases.