Quantitative understanding of volcanic carbon and sulfur emissions has twofold relevance for nature and society:
1) Correlated emissions of carbon and sulfur dioxide (CO2 and SO2) are tracers of the dynamic processes in the volcano interior indicating its activity.
2) Volcanic CO2 and SO2 play an important role for the Earth’s climate and air quality.
Currently available in-situ techniques for measuring CO2 and SO2 volcanic emissions suffer from local
representativeness since they require deployment close to the source which often implies overwhelming effort due to extreme ambient conditions if deployment is possible at all. Remote sensing of volcanic emissions has previously been explored for SO2, while the challenging accuracy required for remote sensing of CO2 point sources hindered its implementation. Recent developments in infrared remote sensing promise much improved accuracy for CO2.
Here, we propose a prototype strategy for simultaneous remote sensing of volcanic CO2 and SO2 emissions. To this end, we combine expertise from University of Heidelberg on remote sensing of SO2 volcanic emissions, and expertise from Karlsruhe Institute of Technology on remote sensing of CO2. We propose to develop a mobile and versatile, ground-based observatory equipped with spectrometers using direct sunlight as a light source enabling combined measurements of the CO2 and SO2 column-average concentrations with the required accuracy. Given the observed concentration records in the plume of a volcano, estimates of the CO2/SO2 emission ratio can be derived and used for tracing volcano activity. The innovative instrumental setup is to be deployed in the vicinity of Mount Etna sampling the overhead emission plume during a 4-week campaign in summer 2015. Given successful demonstration of our remote sensing strategy, future applications open toward supplementing ground-based monitoring networks by replica of our observatory and possibly toward improved disaster forecast.