Processes driving the production, transformation and transport of methane (CH<sub>4</sub>) in wetland ecosystems are highly complex. We present a simple calculation algorithm to separate open-water CH<sub>4</sub> fluxes measured with automatic chambers into diffusion- and ebullition-derived components. This helps to reveal underlying dynamics, to identify potential environmental drivers, and thus, calculate reliable CH<sub>4</sub> emission estimates. The flux separation is based on identification of ebullition-related sudden concentration changes during single measurements. Therefore, a variable ebullition filter is applied, using the lower and upper quartile and the interquartile range (IQR). Automation of data processing is achieved by using an established R-script, adjusted for the purpose of CH<sub>4</sub> flux calculation. The algorithm was tested using flux measurement data (July to September 2013) from a former fen grassland site, converted into a shallow lake as a result of rewetting. Ebullition and diffusion contributed equally (46&thinsp;% and 55&thinsp;%) to total CH<sub>4</sub> emissions, which is comparable to ratios given in literature. Moreover, the separation algorithm revealed a concealed shift in the diurnal trend of diffusive fluxes throughout the measurement period. The water temperature gradient was identified as one of the major drivers of diffusive CH<sub>4</sub> emissions, whereas no significant driver was found in case of erratic CH<sub>4</sub> ebullition events.
Hoffmann, M., Schulz-Hanke, M., Garcia Alba, J., Jurisch, N., Hagemann, U., Sachs, T., … Augustin, J. (2017). A simple calculation algorithm to separate high-resolution CH4 flux measurements into ebullition- and diffusion-derived components. Atmospheric Measurement Techniques, 10(1), 109–118. https://doi.org/10.5194/amt-10-109-2017