Low-frequency modulation of the atmospheric surface layer over Amazonian rain forest and its implication for similarity relationships

摘要: Abstract The application of Monin–Obukhov similarity theory (MOS) is based on empirical relationships derived over uniform surfaces in flat terrain. It not clear to what extent these hold for complex such as tropical forest or hilly This study investigates the influence low-frequency motions structure atmospheric surface layer Amazonian and its implication MOS theory. We test estimation heat fluxes by flux-variance method, which theory, measurements unstable conditions K34 site central Amazonia, north Manaus, Brazil. found that method provide reasonable results only when w − T correlation ( r ) above 0.5. Examining scale dependence u revealed variations tend be well correlated with fluctuations at low frequencies. In this sense, a greater processes tends cause decrease, cannot characterized ‘textbook’ descriptions observed As an alternative conventional scaling, we use ‘dissipation velocity’ uɛ = (kzɛ)1/3, proposed McNaughton [McNaughton, K.G., 2006. On kinetic energy budget layer. Boundary-Layer Meteorol. 118, 83–107], standard deviations parameterize modulation motions. systematic variation stability taken out new parameters, scaled variables become independent parameter ζ. result consistent self-organizing nature turbulent modulated highlight complexities vegetation forest. Estimations υ*/u*, represent outer-layer layer, indicate during roughly 20% time deviates from ‘classical’ description.