Knowledge Bank

The 40% enrichment in mid-stratospheric mass 50 ($\mathrm{<mrow\; data-mjx-texclass="ORD">16</mrow>}O16O18O+16O18O16O$) heavy ozone measured in situ with a mass spectrometer by $Mauoresberger1$ has motivated a large number of laboratory and theoretical investigations as well as additional stratospheric measurement. The stratospheric measurements have confirmed the $\mathrm{<mrow\; data-mjx-texclass="ORD">50</mrow>}O3$enrichment, varies in magnitude from about 10 to 45% At the present time, the mechanism producing these $O3$ isotopic enrichments in not understood. In two previous studies, we reported the identification and quantitative analysis of $\mathrm{<mrow\; data-mjx-texclass="ORD">18</mrow>}O16O16O$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">16</mrow>}O18O16O$ lines in high-resolution infrared ground-based and stratospheric solar absorption $spectra2,3$. This work used the extensive set of ozone spectroscopic parameters summarized by Flaud $etal.4$ Based on these results and the spectroscopic parameters for the $v3$ and $v1$ bands of $\mathrm{<mrow\; data-mjx-texclass="ORD">16</mrow>}O17O16O$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">17</mrow>}O16O16O$ (presented in the accompanying $paper5$), we have searched for absorption features of these rare isotopes in $0.003-cm-1$ resolution stratospheric solar spectra. A number of lines of the $v3$ bands of $\mathrm{<mrow\; data-mjx-texclass="ORD">16</mrow>}O17O16O$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">17</mrow>}O16O16O$ have been identified in the solar spectra. This is the first time that these individual isotopic species have been measured in the Earth’s atmosphere. A quantitative analysis to determine $\mathrm{<mrow\; data-mjx-texclass="ORD">16</mrow>}O17O16O/O3$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">17</mrow>}O16O16O/3$ isotopic ratios is in progress.