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Into the Future with Metrology - The Challenges of Our Environment and Climate


Global greenhouse gas fluxes: Local sources and sinks

Laser hygrometer
Laser hygrometer transfer standard for flux measurements on the new research aircraft of TU Braunschweig. (Figure: Felix Witt, TU Braunschweig)

Anyone who wants to understand climate change and the effects of environmental pollution must do more than just record the current state by measuring the local CO2 concentrations, for example. It is necessary to quantify the sources and sinks of the problematic substances: of water vapor, greenhouse gases (CO2, CH4, N2O), pollutants such as N2O from fertilization, NH3/CH4 from intensive livestock farming or NOx and aerosols/fine dust from traffic. What must be measured is how much substance is exchanged, how fast and where between air/soil/ocean/biosphere, how large these substance fluxes are and how they change. The essential tool for this is the eddy covariance (EC) technique, where the temporal fluctuation of the substance concentration, the gas temperature and vertical wind speed is determined simultaneously and rapidly. For this purpose, PTB and TU Braunschweig are developing a new, very fast laser hygrometer transfer standard for use on their new research aircraft. The aim is to investigate – in cooperation with further partners – in which way, for example, the decline of polar sea ice affects the Arctic heat balance. Projects on CH4 release from landfills or bogs are also planned. Further methods for the determination of substance fluxes aim to record spatial concentration gradients by means of spectroscopic methods in combination with dedicated gas release and detection studies as have been investigated in the IMPRESS and IMPRESS2 projects on PTB's 600 m reference measuring section. It is envisaged to further develop these methods.

Participating department

Opens internal link in current window 3.4 Analytical Chemistry of the Gas Phase