Atmospheric Physics and Chemistry
The composition of the Earth’s atmosphere has undergone extensive change during the last century, with important ramifications for human health, resource management, ecosystem services and the environment. Atmospheric trace constituents (trace gases and aerosols) are key drivers for air quality and climate. Furthermore reactive trace gases (e.g. methane, VOC, NOy, ozone, etc.) control many important feedbacks in the earth system by influencing the oxidizing capacity of the atmosphere and by producing a large fraction of organic aerosol in the atmosphere.
Understanding their exchange at the surface-atmosphere interface as well as their transport throughout the planetary boundary layer and mixing into the free troposphere through entrainment processes remains challenging. Sub-grid scale processes governing the atmospheric fate of reactive trace gases are particularly uncertain and directly relate to uncertainties in future projections of climate and air quality.
The atmospheric physics and chemistry group at ACINN focuses on the development and field deployment of innovative experimental techniques to quantify the chemical composition of the atmosphere. New concepts are explored that allow studying the exchange of trace constituents and their turbulent atmospheric transport in the atmosphere.
· In-situ-techniques to probe the atmosphere
We study natural and anthropogenic contributions to the chemical composition of the atmosphere, interactions of human-made pollutants that have the potential to interact with plant-emitted trace gases, and the biogeochemistry of greenhouse gases. Novel environmental mass spectrometers, such as PTR-MS, PTR-TOF-MS, SRI-QTOFMS are used along with optical techniques (absorption spectroscopy, chemical luminescence, cavitiy ring down spectroscopy) to measure atmospheric trace gases and aerosols. The group develops and maintains surface-atmosphere exchange experiments, engages in ground based and airborne field campaigns and performs controlled laboratory experiments. A particular research specialty is the application of fast in-situ techniques to study the turbulent exchange at the surface – atmosphere interface. In conjunction with process based models we aim to study atmospheric processes, to understand the composition and chemistry of earth's atmosphere, how it functions naturally, and how it is impacted by anthropogenic emissions and changing climate.
· Remote sensing for atmospheric composition
We have working collaborations with experts in UV / VIS / NIR ground-based remote sensing techniques. A series of major trace constitutes in the atmosphere (e.g. ozone, nitrogen dioxide, formaldehyde, aerosols) interact with incoming solar radiation attributed to extinction processes in the UV (ultra violet), VIS (visible) and NIR (near infrared) spectral region. We quantify these processes applying differential optical absorption spectroscopy (DOAS) on direct and scattered solar radiation caught by ground-based sensors. This approach allows to retrieve column and profile information of trace gases as well as aerosol and cloud properties. Our goal at ACInn is both to refine common approaches and to invent new concepts for measuring and retrieving trace constitutes from the ground.
· Snow and ice chemistry
We are interested in atmospheric trace substances and the quality and chemistry of precipitation. One focus is on the chemical composition of seasonal snow and on glacial ice. We seek to understand origin and fate of compounds that are contained in the ice matrix of active rock glaciers. We study the release of ionic substances and heavy metals from active rock glaciers and their impact on the water chemistry of high alpine freshwaters.