Influence of langmuir circulation on the deepening of the wind-mixed layer

Yign Noh, Gahyun Goh, Siegfried Raasch

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Analysis of large eddy simulation data reveals that Langmuir circulation (LC) induces a significant enhancement of the mixed layer deepening, only if the mixed layer depth (MLD) h is shallow and the buoyancy jump across it ΔB is small, when simulations are initiated by applying the wind stress to a motionless mixed layer with stratification. The difference in the entrainment rate between the cases with and without LC decreases with hΔB/υL2, where yL is the velocity scale of LC. The ratio of the mixing length scale l between the cases with and without LC is close to 1 for larger Rt [=(Nl0/q)2; Rt>~1], but it increases to above 10 with the decrease of Rt, where N is the Brunt-Väisälä frequency and q and l0 are the velocity and length scales of turbulence in the homogeneous layer. It is also found that, in the presence of LC, the effect of stratification on vertical mixing should be parameterized in terms of Rt instead of Ri (=(N/S)2), because velocity shear S is no longer a dominant source of turbulence. The parameterization is provided by l/l0=(1+αRt)-1/2 with α~50, regardless of the presence of LC. However, LC makes l0 much larger than conventionally used for the boundary layer.

Original languageEnglish
Pages (from-to)472-484
Number of pages13
JournalJournal of Physical Oceanography
Volume41
Issue number3
DOIs
Publication statusPublished - 2011 Mar 1

Fingerprint

Langmuir circulation
mixed layer
stratification
turbulence
large eddy simulation
vertical mixing
wind stress
entrainment
buoyancy
parameterization
boundary layer

All Science Journal Classification (ASJC) codes

  • Oceanography

Cite this

Noh, Yign ; Goh, Gahyun ; Raasch, Siegfried. / Influence of langmuir circulation on the deepening of the wind-mixed layer. In: Journal of Physical Oceanography. 2011 ; Vol. 41, No. 3. pp. 472-484.
@article{854a6b8875f44428ad2f7b70856e95f0,
title = "Influence of langmuir circulation on the deepening of the wind-mixed layer",
abstract = "Analysis of large eddy simulation data reveals that Langmuir circulation (LC) induces a significant enhancement of the mixed layer deepening, only if the mixed layer depth (MLD) h is shallow and the buoyancy jump across it ΔB is small, when simulations are initiated by applying the wind stress to a motionless mixed layer with stratification. The difference in the entrainment rate between the cases with and without LC decreases with hΔB/υL2, where yL is the velocity scale of LC. The ratio of the mixing length scale l between the cases with and without LC is close to 1 for larger Rt [=(Nl0/q)2; Rt>~1], but it increases to above 10 with the decrease of Rt, where N is the Brunt-V{\"a}is{\"a}l{\"a} frequency and q and l0 are the velocity and length scales of turbulence in the homogeneous layer. It is also found that, in the presence of LC, the effect of stratification on vertical mixing should be parameterized in terms of Rt instead of Ri (=(N/S)2), because velocity shear S is no longer a dominant source of turbulence. The parameterization is provided by l/l0=(1+αRt)-1/2 with α~50, regardless of the presence of LC. However, LC makes l0 much larger than conventionally used for the boundary layer.",
author = "Yign Noh and Gahyun Goh and Siegfried Raasch",
year = "2011",
month = "3",
day = "1",
doi = "10.1175/2010JPO4494.1",
language = "English",
volume = "41",
pages = "472--484",
journal = "Journal of Physical Oceanography",
issn = "0022-3670",
publisher = "American Meteorological Society",
number = "3",

}

Influence of langmuir circulation on the deepening of the wind-mixed layer. / Noh, Yign; Goh, Gahyun; Raasch, Siegfried.

In: Journal of Physical Oceanography, Vol. 41, No. 3, 01.03.2011, p. 472-484.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Influence of langmuir circulation on the deepening of the wind-mixed layer

AU - Noh, Yign

AU - Goh, Gahyun

AU - Raasch, Siegfried

PY - 2011/3/1

Y1 - 2011/3/1

N2 - Analysis of large eddy simulation data reveals that Langmuir circulation (LC) induces a significant enhancement of the mixed layer deepening, only if the mixed layer depth (MLD) h is shallow and the buoyancy jump across it ΔB is small, when simulations are initiated by applying the wind stress to a motionless mixed layer with stratification. The difference in the entrainment rate between the cases with and without LC decreases with hΔB/υL2, where yL is the velocity scale of LC. The ratio of the mixing length scale l between the cases with and without LC is close to 1 for larger Rt [=(Nl0/q)2; Rt>~1], but it increases to above 10 with the decrease of Rt, where N is the Brunt-Väisälä frequency and q and l0 are the velocity and length scales of turbulence in the homogeneous layer. It is also found that, in the presence of LC, the effect of stratification on vertical mixing should be parameterized in terms of Rt instead of Ri (=(N/S)2), because velocity shear S is no longer a dominant source of turbulence. The parameterization is provided by l/l0=(1+αRt)-1/2 with α~50, regardless of the presence of LC. However, LC makes l0 much larger than conventionally used for the boundary layer.

AB - Analysis of large eddy simulation data reveals that Langmuir circulation (LC) induces a significant enhancement of the mixed layer deepening, only if the mixed layer depth (MLD) h is shallow and the buoyancy jump across it ΔB is small, when simulations are initiated by applying the wind stress to a motionless mixed layer with stratification. The difference in the entrainment rate between the cases with and without LC decreases with hΔB/υL2, where yL is the velocity scale of LC. The ratio of the mixing length scale l between the cases with and without LC is close to 1 for larger Rt [=(Nl0/q)2; Rt>~1], but it increases to above 10 with the decrease of Rt, where N is the Brunt-Väisälä frequency and q and l0 are the velocity and length scales of turbulence in the homogeneous layer. It is also found that, in the presence of LC, the effect of stratification on vertical mixing should be parameterized in terms of Rt instead of Ri (=(N/S)2), because velocity shear S is no longer a dominant source of turbulence. The parameterization is provided by l/l0=(1+αRt)-1/2 with α~50, regardless of the presence of LC. However, LC makes l0 much larger than conventionally used for the boundary layer.

UR - http://www.scopus.com/inward/record.url?scp=79954987534&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=79954987534&partnerID=8YFLogxK

U2 - 10.1175/2010JPO4494.1

DO - 10.1175/2010JPO4494.1

M3 - Article

AN - SCOPUS:79954987534

VL - 41

SP - 472

EP - 484

JO - Journal of Physical Oceanography

JF - Journal of Physical Oceanography

SN - 0022-3670

IS - 3

ER -