Speaker
Description
Atmospheric ozone plays an important role in the chemistry of volcanic plumes, for instance its photolysis is a source of hydrogen radicals and it oxidises halogen atoms and hydrocarbons. The ozone level inside a plume is therefore a good indicator of turbulent mixing and chemical activity. For instance, already small amounts of halogen oxides can lead to significant or even complete O$_3$ destruction. At the same time O$_3$ is difficult to measure in volcanic plumes due to the interference of other constituents on common O$_3$ measuring devices. In particular, SO$_2$ has a positive interference with the most common technique for O$_3$ measurement, short-path UV absorption. Typically, the interference signal due to volcanic SO$_2$ will exceed the atmospheric O$_3$ signal by one to two orders of magnitude. Therefore, it is difficult to find reliable O$_3$ measurements in volcanic plumes.
Here we present a lightweight (< 2 kg) O$_3$ instrument based on gas-phase chemiluminescence following the O$_3$ + C$_2$H$_4$ (Ethylene) reaction, which is suited for ground based and airborne (drone) deployment. We discuss the detection limit, response time, and possible interferences of the instrument as well as studies made possible by the instrument.
