A Finite-Time Ensemble Method for Mixed Layer Model Comparison

This work evaluates the fidelity of various upper-ocean turbulence parameterizations subject to realistic monsoon forcing and presents a finite-time ensemble vector (EV) method to better manage the design and numerical principles of these parameterizations. The EV method emphasizes the dynamics of a...

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Bibliographic Details
Published inJournal of physical oceanography Vol. 53; no. 9; pp. 2211 - 2230
Main Authors Johnson, Leah, Fox-Kemper, Baylor, Li, Qing, Pham, Hieu T., Sarkar, Sutanu
Format Journal Article
LanguageEnglish
Published Boston American Meteorological Society 01.09.2023
Subjects
boundary layer
Boundary layers
Case studies
Dynamical systems
Langmuir circulation
Langmuir turbulence
Langmuir waves
Large eddy simulation
Large eddy simulations
Mixed layer
Monsoon onset
Monsoons
Ocean surface
Oceanic eddies
Oceanic turbulence
oceanography
Oceans
Physics
Simulation
Surface boundary layer
System theory
Turbulence
Turbulence models
Variables
Velocity
Wind
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Summary:This work evaluates the fidelity of various upper-ocean turbulence parameterizations subject to realistic monsoon forcing and presents a finite-time ensemble vector (EV) method to better manage the design and numerical principles of these parameterizations. The EV method emphasizes the dynamics of a turbulence closure multimodel ensemble and is applied to evaluate 10 different ocean surface boundary layer (OSBL) parameterizations within a single-column (SC) model against two boundary layer large-eddy simulations (LES). Both LES include realistic surface forcing, but one includes wind-driven shear turbulence only, while the other includes additional Stokes forcing through the wave-average equations that generate Langmuir turbulence. The finite-time EV framework focuses on what constitutes the local behavior of the mixed layer dynamical system and isolates the forcing and ocean state conditions where turbulence parameterizations most disagree. Identifying disagreement provides the potential to evaluate SC models comparatively against the LES. Observations collected during the 2018 monsoon onset in the Bay of Bengal provide a case study to evaluate models under realistic and variable forcing conditions. The case study results highlight two regimes where models disagree 1) during wind-driven deepening of the mixed layer and 2) under strong diurnal forcing.
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Office of Naval Research (ONR)
USDOE Office of Science (SC), Biological and Environmental Research (BER)
ISSN:0022-3670
1520-0485
DOI:10.1175/JPO-D-22-0107.1