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Implications of non-local transport and conditionally averaged statistics on Monin- Obukhov similarity theory and Townsend ´s attached eddy hypothesis Li, Qi Gentine, Pierre Mellado González, Juan Pedro McColl, Kaighin Universitat Politècnica de Catalunya. Departament de Física Àrees temàtiques de la UPC::Física Eddies -- Simulation models Similarity (Physics) Turbulència -- Models matemàtics According to Townsend’s hypothesis, so-called wall-attached eddies are the main contributors to turbulent transport in the atmospheric surface layer (ASL). This is also one of the main assumptions of Monin–Obukhov similarity theory (MOST). However, previous evidence seems to indicate that outerscale eddies can impact theASL, resulting in deviations from the classic MOST scaling. We conduct largeeddy simulations and direct numerical simulations of a dry convective boundary layer to investigate the impact of coherent structures on the ASL. A height-dependent passive tracer enables coherent structure detection and conditional analysis based on updrafts and subsidence. The MOST similarity functions computed from the simulation results indicate a larger deviation of the momentum similarity function fm from classical scaling relationships compared to the temperature similarity function fh. The conditionalaveraged fm for updrafts and subsidence are similar, indicating strong interactions between the inner and outer layers. However, fh conditioned on subsidence follows the mixed-layer scaling, while its updraft counterpart is well predicted by MOST. Updrafts are the dominant contributors to the transport of momentum and temperature. Subsidence, which comprises eddies that originate from the outer layer, contributes increasingly to the transport of temperature with increasing instability. However, u0 of different signs are distributed symmetrically in subsidence unlike the predominantly negative u0 as instability increases. Thus, the spatial patterns of u0w0 differ compared to u0w0 in regions of subsidence. These results depict the mechanisms for departure from the MOST scaling, which is related to the stronger role of subsidence. Peer Reviewed Postprint (published version) 2018-10-01 Article Li, Q. [et al.]. Implications of non-local transport and conditionally averaged statistics on Monin- Obukhov similarity theory and Townsend ´s attached eddy hypothesis. "Journal of the atmospheric sciences", 1 Octubre 2018, vol. 75, p. 3403-3431. 0022-4928 https://hdl.handle.net/2117/179802 10.1175/JAS-D-17-0301.1 eng https://journals.ametsoc.org/doi/full/10.1175/JAS-D-17-0301.1 http://creativecommons.org/licenses/by-nc-nd/3.0/es/ Open Access Attribution-NonCommercial-NoDerivs 3.0 Spain 29 p. application/pdf