New Perspectives in Eddy Covariance Measurements Using Aircraft-Based Technology

Much progress has been achieved during the last thirty years in measuring mass and energy exchange using aircraft-based sensors. Large scale projects over agricultural and forested regions have given scientists the opportunity to test and improve flux measurement techniques. As part of these projects, fluxes of latent and sensible heat as well as CO₂ and O₃ have been obtained over extended periods of time, over a wide range of spatial scales, using measurements from tower and aircraft-based systems. The progress achieved and lesson learned will be reviewed. The frequently mentioned problem of the underestimation of fluxes using the eddy covariance technique will be discussed. One of the main causes of the lack of energy budget closure is most likely mesoscale transfer. Aircraft-based flux measurements can provide valuable information on this topic. Using wavelet analysis, the magnitude of this transfer will be presented for several scalars for a wide range of landscapes. The use of wavelet analysis to minimize the impact of non-stationary conditions on eddy covariance estimates will also be discussed.