资源环境科技发展态势分析平台

Density effect corrections (DEC) are applied to adjust raw CO₂ fluxes measured by eddy covariance (EC) systems with open‐path gas analyzers. DEC is also required for adjusting the measured CO₂ concentration fluctuations to obtain the adjusted CO₂ concentrations for analyzing turbulent statistics or quantifying fluxes. However, our data show that the power spectra of the DEC‐adjusted CO₂ concentrations are distorted in the high frequency range, as compared with the corresponding spectra of temperature and water vapor density. This contradicts the similarity behavior of scalars, as suggested by Monin‐Obukhov similarity theory. It is demonstrated that such a distortion is caused by the DEC‐induced spikes in the DEC‐adjusted CO₂, altering turbulent statistics of CO₂ and scalar similarity between CO₂ and other scalars. Our results suggest that CO₂ fluxes are overestimated by applying DEC especially under high Bowen ratio conditions, potentially leading to substantial uncertainties in long‐term ecosystem carbon exchange in dry regions.