scholarly journals Global Impacts of Subseasonal (<60 Day) Wind Variability on Ocean Surface Stress, Buoyancy Flux, and Mixed Layer Depth

2019 ◽  
Vol 124 (12) ◽  
pp. 8798-8831 ◽  
Author(s):  
D. B. Whitt ◽  
S. A. Nicholson ◽  
M. M. Carranza
Keyword(s):  
Mixed Layer ◽  
Surface Stress ◽  
Mixed Layer Depth ◽  
Ocean Surface ◽  
Buoyancy Flux ◽  
Layer Depth ◽  
Wind Variability ◽  
Global Impacts

scholarly journals Scaling Surface Mixing/Mixed Layer Depth under Stabilizing Buoyancy Flux

2015 ◽  
Vol 45 (1) ◽  
pp. 247-258 ◽  
Author(s):  
Yutaka Yoshikawa
Keyword(s):  
Mixed Layer ◽  
Mixed Layer Depth ◽  
Mixing Layer ◽  
Buoyancy Flux ◽  
Earth’S Rotation ◽  
Surface Mixed Layer ◽  
Threshold Method ◽  
Layer Depth ◽  
Earth's Rotation ◽  
Surface Buoyancy

AbstractThis study concerns the combined effects of Earth’s rotation and stabilizing surface buoyancy flux upon the wind-induced turbulent mixing in the surface layer. Two different length scales, the Garwood scale and Zilitinkevich scale, have been proposed for the stabilized mixing layer depth under Earth’s rotation. Here, this study analyzes observed mixed layer depth plus surface momentum and buoyancy fluxes obtained from Argo floats and satellites, finding that the Zilitinkevich scale is more suited for observed mixed layer depths than the Garwood scale. Large-eddy simulations (LESs) reproduce this observed feature, except under a weak stabilizing flux where the mixed layer depth could not be identified with the buoyancy threshold method (because of insufficient buoyancy difference across the mixed layer base). LESs, however, show that the mixed layer depth if defined with buoyancy ratio relative to its surface value follows the Zilitinkevich scale even under such a weak stabilizing flux. LESs also show that the mixing layer depth is in good agreement with the Zilitinkevich scale. These findings will contribute to better understanding of the response of stabilized mixing/mixed layer depth to surface forcings and hence better estimation/prediction of several processes related to stabilized mixing/mixed layer depth such as air–sea interaction, subduction of surface mixed layer water, and spring blooming of phytoplankton biomass.

scholarly journals Interannual Variability of the Mixed Layer Winter Convection and Spice Injection in the Eastern Subtropical North Atlantic

2015 ◽  
Vol 45 (2) ◽  
pp. 504-525 ◽  
Author(s):  
Nicolas Kolodziejczyk ◽  
Gilles Reverdin ◽  
Alban Lazar
Keyword(s):  
Interannual Variability ◽  
Mixed Layer ◽  
North Atlantic ◽  
Mixed Layer Depth ◽  
Buoyancy Flux ◽  
Upper Ocean ◽  
Late Winter ◽  
Layer Depth ◽  
Ocean Layer ◽  
Bulk Model

AbstractThe Argo dataset is used to study the winter upper-ocean conditions in the northeastern subtropical (NEA) Atlantic during 2006–12. During late winter 2010, the mixed layer depth is abnormally shallow and a negative anomaly of density-compensated salinity, the so-called spiciness, is generated in the permanent pycnocline. This is primarily explained by unusual weak air–sea buoyancy flux during the late winter 2010, in contrast with the five other studied winters. Particularly deep mixed layers and strong spiciness anomalies are observed during late winter 2012. The 2010 winter conditions appear to be related to historically low North Atlantic Oscillation (NAO) and high tropical North Atlantic index (TNA). Interannual variability of the eastern subtropical mixed layer is further investigated using a simple 1D bulk model of mean temperature and salinity linear profiles, based on turbulent kinetic energy conservation in the upper-ocean layer, and forced only with seasonal air–sea buoyancy forcing corresponding to fall–winter 2006–12. It suggests that year-to-year variability of the winter convective mixing driven by atmospheric buoyancy flux is able to generate interannual variability of both late winter mixed layer depth and spiciness in a strongly compensated layer at the base of the mixed layer and in the permanent pycnocline.

scholarly journals Seasonal Variability of The Mixed Layer Depth in The Sulawesi Sea

2021 ◽  
Vol 6 (3) ◽  
pp. 163
Author(s):  
Mochamad Riza Iskandar ◽  
Prima Wira Kusuma Wardhani ◽  
Toshio Suga
Keyword(s):  
Wind Stress ◽  
Mixed Layer ◽  
Mixed Layer Depth ◽  
World Ocean ◽  
Southwest Monsoon ◽  
Buoyancy Flux ◽  
Freshwater Flux ◽  
Layer Depth ◽  
Reanalysis Dataset ◽  
Mechanical Forcing

The Sulawesi Sea is a semi-enclosed basin located in the Indonesian Seas and considered as the one of location in the west route of Indonesian Throughflow (ITF). There is less attention on the mixed layer depth investigation in the Sulawesi Sea. Concerning that the mixed layer plays an important role in influencing the ocean in air-sea interaction and affects biological activity, the estimation of mixed layer depth (MLD) in the Sulawesi Sea is important. Seasonal variation of the mixed layer in the Sulawesi Sea between 115°-125°E and 0°-8°N is estimated by using World Ocean Atlas 2013. Forcing elements on the mixed layer in terms of surface-forced turbulent mixing from mechanical forcing of wind stress and buoyancy forcing (from heat flux as well as freshwater flux) in the Sulawesi Sea is provided by using a reanalysis dataset. The MLD is estimated directly on grid profiles with interpolated levels based on chosen density fixed criterion of 0.03 kg.m<sup>-3</sup> and temperature criterion of 0.5°C difference from the surface. The results show that mixed layer depth in the Sulawesi Sea varies both spatially and temporally. Generally, the deepest MLD was occurred during the southwest monsoon (JJA), and the lowest MLD was occurred during the first transition (MAM) and second transition monsoon (SON). Strengthening and weakening MLD are influenced by mechanical forcing from wind stress and buoyancy flux. In the Sulawesi Sea, the mixed layer deepening coincides with the occurrence of a maximum in wind stress, and low buoyancy flux at the surface. This condition is the opposite when mixed layer shallowing occurs.

scholarly journals Note on the Rate of Restratification in the Baroclinic Spindown of Fronts

2018 ◽  
Vol 48 (7) ◽  
pp. 1543-1553 ◽  
Author(s):  
Jörn Callies ◽  
Raffaele Ferrari
Keyword(s):  
Mixed Layer ◽  
Environmental Conditions ◽  
Initial Phase ◽  
Nonlinear Evolution ◽  
Mixed Layer Depth ◽  
Buoyancy Flux ◽  
Layer Depth ◽  
Coriolis Parameter ◽  
Coarse Resolution ◽  
Geostrophic Shear

AbstractThis paper revisits how the restratifying buoyancy flux generated by baroclinic mixed layer instabilities depends on environmental conditions. The frontal spindown is shown to produce buoyancy fluxes that increase significantly beyond the previously proposed and widely used scaling (f is the Coriolis parameter, Λ is the geostrophic shear, and H is the mixed layer depth), irrespective of whether the initial front is broad or narrow. This increase occurs after the initial phase of the nonlinear evolution, when the baroclinic eddies grow in size and develop velocities significantly in excess of the scaling assumption V ~ ΛH. Implications for parameterizing the restratification caused by baroclinic mixed layer instabilities in coarse-resolution models are discussed.

scholarly journals Surface buoyancy flux in Bay of Bengal and Arabian Sea

2008 ◽  
Vol 26 (3) ◽  
pp. 395-400 ◽  
Author(s):  
G. Anitha ◽  
M. Ravichandran ◽  
R. Sayanna
Keyword(s):  
Mixed Layer ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Mixed Layer Depth ◽  
Buoyancy Flux ◽  
Layer Depth ◽  
Obukhov Length ◽  
Surface Buoyancy ◽  
Quantitative Influence ◽  
Surface Buoyancy Flux

Abstract. The seasonal variation of thermal, haline, net surface buoyancy flux, the Monin-Obukhov length (M-O length, L) and stability parameter, i.e. the ratio of M-O length to mixed layer depth (h) were studied in the Bay of Bengal (BoB) and the Arabian Sea (AS) for the years 2003 and 2004 using Argo temperature and salinity profiles. The relative quantitative influence of winds to surface buoyancy and the applicability of scaling mixed layer using M-O length in BoB and AS was brought out. Rotation and light penetration modify the mixed layer depth from M-O length during shoaling in spring giving L/h<1.

Interannual variability of the Tropical Indian Ocean mixed layer depth

2012 ◽  
Vol 40 (3-4) ◽  
pp. 743-759 ◽  
Author(s):  
M. G. Keerthi ◽  
M. Lengaigne ◽  
J. Vialard ◽  
C. de Boyer Montégut ◽  
P. M. Muraleedharan
Keyword(s):  
Indian Ocean ◽  
Interannual Variability ◽  
Mixed Layer ◽  
Mixed Layer Depth ◽  
Tropical Indian Ocean ◽  
Ocean Mixed Layer ◽  
Layer Depth ◽  
Ocean Mixed Layer Depth

scholarly journals Summertime increases in upper-ocean stratification and mixed-layer depth

Nature ◽  
2021 ◽  
Vol 591 (7851) ◽  
pp. 592-598
Author(s):  
Jean-Baptiste Sallée ◽  
Violaine Pellichero ◽  
Camille Akhoudas ◽  
Etienne Pauthenet ◽  
Lucie Vignes ◽  
...  
Keyword(s):  
Mixed Layer ◽  
Mixed Layer Depth ◽  
Upper Ocean ◽  
Layer Depth ◽  
Ocean Stratification
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