Details
| Original language | English |
|---|---|
| Pages (from-to) | 472-484 |
| Number of pages | 13 |
| Journal | Journal of physical oceanography |
| Volume | 41 |
| Issue number | 3 |
| Publication status | Published - 1 Mar 2011 |
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.
Keywords
- Large eddy simulation, Mixed layer, Oceanic mixed layer
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Oceanography
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In: Journal of physical oceanography, Vol. 41, No. 3, 01.03.2011, p. 472-484.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Influence of langmuir circulation on the deepening of the wind-mixed layer
AU - Noh, Yign
AU - Goh, Gahyun
AU - Raasch, Siegfried
N1 - This work was supported by the National Research Foundation of Korea Grant funded by the Korean Government (MEST) (NRF-2009-C1AAA001- 0093068), by the Korean Ocean Research and Develop- ment Institute (KORDI) research program PE98512, and by the project ‘‘Research for the Meteorological Obser- vation Technology and Its Application’’ at the National Institute of Meteorological Research.
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.
KW - Large eddy simulation
KW - Mixed layer
KW - Oceanic mixed layer
UR - http://www.scopus.com/inward/record.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 -