Liu, H; Randerson, JT; Lindfors, J; Massman, W; Foken, T: Consequences of incomplete surface energy balance closure for CO2 fluxes from open-path CO2/H2O infrared gas analyzers, Boundary-Layer Meteorology, 120, 65-85 (2006), doi:DOI 10.1007/s10546-005-9047-z | |
Abstract: We present an approach for ssessing the impact of systematic biases in measured energy fluxes on CO2 flux estimates obtained from open-path eddy covariance systems. In our analysis, we present equations to analyze the propagation of errors through the Webb, Pearman, and Leuning (WPL) algorithm (Quart. J. Roy. Meteorol. Soc., 106, 85-100, 1980) that is widely used to account for density fluctuations on CO2 flux measurements. Our results suggest that incomplete energy balance closure does not necessarily lead to underestimation of CO2 fluxes despite the existence of surface energy imbalance; either an overestimation or underestimation of CO2 fluxes is possible depending on local atmospheric conditions and measurement errors of the kinematic heat, moisture, and CO2 fluxes. We use open-path eddy covariance fluxes measured over a black spruce forest near Delta Junction in interior Alaska in the 2002 summer growing season to explore several energy imbalance scenarios and their consequences for CO2 fluxes. |