Large Turbulent Eddies and Turbulent Flux Exchange Processes over Heterogeneous Landscapes

Evidence has shown that large turbulent eddies have great impacts on turbulent fluxes and thus the non-closure of the surface energy balance. However, a mechanistic link between large eddies and turbulent fluxes remains unclear. Here we studied the influence of large turbulent eddies on turbulence structures and exchange processes by using data collected over different landscapes including a lake, a patched irrigated crop field, and a shrub land. Landscape heterogeneity led to changes in attributes of large turbulent eddies. As a consequence, these large eddies created different low-frequency signals in different time-series data of temperature, humidity, and CO₂ measured by eddy covariance systems. We analyzed and will demonstrate how changes in turbulence structures were linked to changes in the attributes of large eddies in response to changes in land surface heterogeneity. Therefore, landscape heterogeneity, which exists at different landscape scales, may be one key factor responsible for departures of turbulent structures from those described by Monin-Obukhov similarity theory.