Open AccessDiagnosing the Thickness‐Weighted Averaged Eddy‐Mean Flow Interaction From an Eddying North Atlantic Ensemble: The Eliassen‐Palm Flux
Author(s) -
Uchida Takaya,
Jamet Quentin,
Dewar William K.,
Le Sommer Julien,
Penduff Thierry,
Balwada Dhruv
Publication year - 2022
Publication title -
journal of advances in modeling earth systems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.03
H-Index - 58
ISSN - 1942-2466
DOI - 10.1029/2021ms002866
Subject(s) - eddy , gulf stream , geology , mean flow , mesoscale meteorology , flux (metallurgy) , residual , zonal flow (plasma) , flow (mathematics) , climatology , zonal and meridional , convergence (economics) , mechanics , statistical physics , meteorology , physics , turbulence , mathematics , algorithm , materials science , plasma , quantum mechanics , economic growth , economics , metallurgy , tokamak
The thickness‐weighted average (TWA) framework, which treats the residual‐mean flow as the prognostic variable, provides a clear theoretical formulation of the eddy feedback onto the residual‐mean flow. The averaging operator involved in the TWA framework, although in theory being an ensemble mean, in practice has often been approximated by a temporal mean. Here, we analyze an ensemble of North Atlantic simulations at mesoscale‐permitting resolution (1/12°). We therefore recognize means and eddies in terms of ensemble means and fluctuations about those means. The ensemble dimension being orthogonal to the temporal and spatial dimensions negates the necessity for an arbitrary temporal or spatial scale in defining the eddies. Eddy‐mean flow feedbacks are encapsulated in the Eliassen‐Palm (E‐P) flux tensor and its convergence indicates that eddy momentum fluxes dominate in the separated Gulf Stream. The eddies can be interpreted to contribute to the zonal meandering of the Gulf Stream and a northward migration of it in the meridional direction. Downstream of the separated Gulf Stream in the North Atlantic Current region, the interfacial form stress convergence becomes leading order in the E‐P flux convergence.