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A dynamic extension of the pragmatic blending scheme for scale‐dependent sub‐grid mixing
Author(s) -
Efstathiou Georgios A.,
Plant Robert S.
Publication year - 2019
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.3445
Subject(s) - scheme (mathematics) , turbulence , grid , mixing (physics) , mesoscale meteorology , boundary layer , representation (politics) , boundary (topology) , scale (ratio) , statistical physics , flow (mathematics) , computer science , large eddy simulation , classification scheme , mechanics , mathematics , meteorology , physics , mathematical analysis , geometry , quantum mechanics , politics , political science , law , information retrieval
A recent pragmatic blending approach treats sub‐grid turbulent mixing using a weighted average of a 1D mesoscale model and a 3D Smagorinsky formulation. Here the approach is modified and extended to incorporate a scale‐dependent dynamic Smagorinsky scheme instead of a static Smagorinsky scheme. Results from simulating an evolving convective boundary layer show that the new scheme is able to improve the representation of turbulence statistics and potential temperature profiles at grey‐zone resolutions during the transition from the shallow morning to the deep afternoon boundary layer. This is achieved mainly because the new scheme enables and controls an improved spin‐up of resolved turbulence. The dynamic blending scheme is shown to be more adaptive to the evolving flow and somewhat less sensitive to the blending parameters. The new approach appears to offer a more robust and more flexible formulation of blending and the results strongly encourage further assessment and development.