Research profile seminar
Two PhD students will tell us about their research.
Understanding the role of anthropogenic and biogenic volatile organiccompounds (VOC) on the secondary organic aerosol (SOA)
Epameinondas Tsiligianis, Department of Chemistry and Molecular Biology, University of Gothenburg
Understanding the properties and formation of secondary organic aerosol (SOA) is of great importance, as SOA represents a dominant fraction of the tropospheric aerosol and there is still insufficient knowledge about them (Hallquist et al., 2009). SOA processes of interest are ranging from remote and pristine areas (Kristensen et al., 2016), to heavy polluted atmospheres such as the photochemical smog in China (Hallquist et al., 2016). An anthropogenic aerosol precursor, 1,3,5 trimethylbenzene (TMB) ¿ one of the most reactive anthropogenic volatile organic compound (AVOC) in the gas exhausts, and a biogenic one, isoprene ¿ the most common biogenic VOC (BVOC) emitted from vegetation, were used in order to investigate the role of the VOCs in the production of atmospheric SOA. TMBoxidation experiments by hydroxyl radicals (OH) under different NOx conditions were conducted using the Gothenburg potential aerosol mass reactor (Go:PAM), while the isoprene experiments were performed in the atmospheric simulation chamber SAPHIR in Forschungszentrum Jülich, using nitrate radicals (NO3) as the oxidant. A high resolution time of flight chemical ionization mass spectrometer (HR-ToF-CIMS) was applied to characterize the oxidation products in both cases. The HR-ToF-CIMS technique can utilize different reagent ion choices (e.g. I-, NO3-, H3O+, CH3CO2-) enabling detection of a broad range of compounds with high time resolution (~1 Hz). For measurements including the particle phase a special inlet has been used, Filter Inlet for Gases and AEROsols (FIGAERO) (Lopez-Hilfiker et al., 2014), providing a time resolution of ca 30 min. Several hundred or even thousands of different organic compounds are detected with these methods, illustratingthe complexity of SOA.The presentation will highlight results from the aforementioned measurements with HR-ToF-CIMS in relation to their potential in forming particles and the corresponding mechanisms.
Rising future tropical cyclone induced extreme winds in the Mekong River Basin
Aifang Chen, Department of Earth Sciences, University of Gothenburg
The societal impact of extreme winds induced by tropical cyclones (TCs) is a major concern in the Mekong River Basin (MRB). Though no clear trend of landfalling TC intensity along the Vietnam coastline has been observed since the 1970s, climate models predict increasing TC intensity in the 21st century over the Western North Pacific which is the primary TC source region influencing the MRB. Yet, how future TC activities will affect extreme winds in the MRB remains unclear. By employing a novel dynamical downscaling technique using a specialized, coupled ocean-atmospheric model, we here show the potential increases in TC intensity in the MRB for 2081-2100 compared to 1981-2000, along with shorter return periods of extreme events with maximum wind speed. Meanwhile, distinct TC intensity increases in the coastal area reveal worrisome future TC-related risks that may jeopardize sustainable development, disrupt food supply, and exacerbate conflicts, ranging from regional to global scales.
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