methane fluxes; greenhouse gas budget; agricultural emissions; stable isotopes; Kyoto Protocol; Switzerland; Methane flux
Stieger Jacqueline, Bamberger Ines, Buchmann Nina, Eugster Werner (2015), Validation of farm-scale methane emissions using nocturnal boundary layer budgets, in Atmos. Chem. Phys.
, 15, 14055-14069.
Merbold L, Eugster W, Stieger J, Zahniser M, Nelson D, Buchmann N (2014), Greenhouse gas budget (CO2, CH4 and N2O) of intensively managed grassland following restoration, in Global Change Biology
, 20, 1913-1928.
Bamberger I, Stieger J, Eugster W, Buchmann N (2014), Spatial variability of methane: Attributing atmospheric concentrations to emissions, in Environmental Pollution
, 190, 65-74.
Wolf Sebastian, Eugster Werner, Ammann Christof, Häni Matthias, Zielis Sebastian, Hiller Rebecca, Stieger Jacqueline, Imer Dennis, Merbold Lutz, Buchmann Nina (2013), Contrasting response of grassland versus forest carbon and water fluxes to spring drought in Switzerland, in Environmental Research Letters
, 8, 035007.
Eugster Werner, Kling George W. (2012), Performance of a low-cost methane sensor for ambient concentration measurements in preliminary studies, in Atmospheric Measurement Techniques
, 5, 1925-1934.
Stieger Jacqueline V., Methane emissions at farm and regional scales: origin, magnitude and spatio-temporal variability
, ETH Zurich, ETH Zurich.
1. Relevance:The release of the IPCC’s Fourth Climate Assessment Report has once more drawn the public attention to the important role that agriculture plays in the global greenhouse gas budgets, namely in the case of CH4 and N2O. In Switzerland, 80.5% of all national CH4 emissions stem from the agricultural sector (year 2007 values). However, these numbers so far lack direct experimental validation in the field and are based on expert knowledge. We thus propose to investigate the CH4 emission processes leading to a clear increase in CH4 concentrations within the nocturnal atmospheric boundary layer. The proposed project will thus aim at validating CH4 emissions at the farm scale as a first step towards a validation at the national scale. 2. Working Hypotheses:We hypothesize that the diurnal cycle in CH4 concentration is the combination of the local surface exchange of CH4 (measured by eddy covariance) with oxidation by the soil if it is unsaturated or emissions from the soil if saturated, plus a much larger component attributable to emissions from cattle (ruminants). 3. Specific Aim:Our specific aim is to quantify CH4 emissions at the farm scale (0.5- 5 km2) of the ETH Research Station Chamau and relate this to estimates reported in the Swiss National Inventory Report under the Kyoto Protocol.4. Experimental Design and Methods:We plan to employ a boundary-layer budgeting method (BLBM; Section 2.4.5) by focusing on the nocturnal boundary layer conditions where steadily increasing CH4 concentrations can be observed during most of the nights. To achieve this, we need the following four components of our experiment: A. Eddy covariance flux and concentration measurements to quantify the surface exchange of CH4 (soil production or consumption) (Section 2.4.1) B. Vertical CH4 concentration profiles to know the vertical distribution of CH4 in the incompletely mixed stable nocturnal boundary layer (NBL), to determine the NBL height and its temporal evolution which are essential information required by the BLBM (Section 2.4.2) C. Spatial variation of near-surface CH4 concentrations to address the question how spatially representative our near-surface CH4 concentration measurements actually are; for this we plan the use of a car to move a CH4 analyser along transects during daytime and nighttime, and a small aircraft to probe the lowest 50-3000 m during daytime (Section 2.4.3) D. Measurements of stable isotopes, in particular d13C ratios in CH4 will provide additional information about the processes responsible for the CH4 fluxes obtained via the BLBM aproach (Section 2.4.4) 5. Expected Value of the Proposed Project:Our project will contribute to develop and test a potentially useful method for validating CH4 emissions at the farm scale and larger scales. This project will contribute to our scientific understanding by bridging the spatial and temporal gap in our efforts to quantify and validate CH4 emission estimates at the farm scale to regional scale. And this project is expected to provide an essential basis for the developments of the European Integrative Carbon Observation System (ICOS).