Partitioning of carbon dioxide exchange in rapidly and slowly changing ecosystems

A key question in times of climate change is, how the biosphere responds to global change and the local land use management in regard to its carbon cycle. At the present time, the land surface acts as a sink for an thropogenic carbon dioxide (CO$_{2}$) emissions. However, additional CO$_{2}$ recarried out in winter wheat, winter barley, and in an intercrop mixture during different plant development stage and at diffrent times of day. A gas analyzer continuously records the concentrations at a frequency of 20 s$^{−1}$ over a 2 m profile height. We present a post-processing technique of the measurements (e.g. the correction of timelags) and show the resulting vertical profiles as 30-minute averages over height steps of 0.025m. The profiles clearly show the effects of soil respiration and photosynthetic carbon uptake within the plant stand, which vary both during the time of day and during the vegetation period. Using the Monin-Obukhov similarity theory, measurements over bare soil and a short plant canopy were analyzed to check the validity of the elevator measurements and the raw data processing. It was found that the derived fluxes of CO$_{2}$, latent and sensible heat, and momentum correlated well with eddy-covariance (EC) measurements [...