Improved parameterization of the commonly used exponential equation for calculating soil-atmosphere exchange fluxes from closed-chamber measurements

The concentration change in a closed chamber derived from Fick’s law for a steady flux leads to a differential equation which describes an exponential curve of limited growth. Here we introduce and compare an alternative parameterization with those commonly used in the chamber flux community when investigating soil-atmosphere exchange of N2O, CH4, or CO2 using classical gas chromatography systems, infrared gas analyzers, or novel laser absorption spectrometers. This new parameterization has the advantages that the parameters are mathematically less dependent leading to a more stable regression and that all parameters are physically meaningful with one of them being the main quantity of interest, i.e. the initial flux at chamber closure.