Physics Colloquium, Huilin Chen, Center for Isotope Research (CIO) University of Groningen

Abstract:

The atmospheric mole fractions of major long-lived greenhouse gases, i.e. carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) are increasing due to human activities. The rise of the greenhouse gases in the atmosphere is the main cause of global warming. The 2015 United Nations Climate Change Conference in Paris (COP21) agreed to limit global warming "well below" 2°C and, if possible, below 1.5°C. This requires not only massive reductions or even negative emissions in greenhouse gases, but also advanced understanding of their sources and sinks and the possible responses and feedbacks of the terrestrial ecosystem to make reliable climate projections. However, contemporary carbon cycle models are not capable of accurately simulating gross biospheric fluxes, i.e. Gross Primary Production (GPP), and respiration, and cannot reliably predict the responses of the terrestrial ecosystem to changing temperature and precipitation regimes.

To improve our understanding of biospheric gross fluxes, high-accuracy in situ atmospheric vertical profile measurements and direct leaf chamber measurements of carbonyl sulfide (COS), a tracer to quantify GPP, were made at a boreal forest in Hyytiälä, Finland and in Lutjewad, Netherlands. The measurements bridge the gap between the ecosystem COS fluxes and the estimate of GPP on the ecosystem scale, and further on the regional scale. Furthermore, the recent development of an unmanned aerial vehicle (UAV) based measurements of greenhouse gases will be shown, followed by the potential and challenges of UAV-based measurements of COS.