Airborne Measurements of Inorganic Acids during the Deep Convective Clouds and Chemistry (DC3) Experiment

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The Deep Convective Clouds and Chemistry (DC3) field campaign seeks to characterize the impact of convective systems on the chemistry and composition of the upper troposphere (UT). This project supports the deployment of a newly built chemical ionization mass spectrometer (CIMS) on the NSF/NCAR G-V aircraft to measure pernitric acid (HO2NO2), nitric acid (HNO3), hydrochloric acid (HCl), and sulfur dioxide (SO2). These observations will be interpreted to evaluate the impact of convection on UT photochemistry. HNO3 and HO2NO2 measured in and around convective outflow will provide valuable constraints on the chemical processes in these environments. The HO2NO2 observations will be particularly useful as the relatively short lifetime of this species makes it very sensitive to radical levels. Photochemical calculations will be performed to predict the observed HO2NO2 levels as well as the time evolution of the observed HNO3. This will allow a critical test of our understanding of processes that control radical levels and ozone production in the UT. Observations of SO2 will be used to assess the cloud processing of this species and serve as a useful comparison point with other aircraft involved in DC3. The HCl observations will serve as a tracer for stratospheric influence and provide a marker for lower altitude mid-continent chlorine chemistry. The information generated through this project will improve understanding of the impacts of convective storms on atmospheric chemistry. In addition, the CIMS instrument will become part of the facilities at NCAR and available for future investigators on the G-V. The project will support one Ph.D. student and form the core of his/her dissertation research. Two undergraduate students will gain valuable research experience through participation in the project. Finally, the PI will partner with a local Atlanta area high school to facilitate exposure of underrepresented minorities to higher education and scientific research.