The Response of Oceanic Mixed Layer Depth to Physical Forcing: Modelled vs. Observed

1991 ◽  
Vol 181 (2) ◽  
pp. 360-361 ◽  
Author(s):  
M. M. O'Brien ◽  
A. Plueddemann ◽  
R. A. Weller
Keyword(s):  
Mixed Layer ◽  
Mixed Layer Depth ◽  
Layer Depth ◽  
Oceanic Mixed Layer ◽  
Physical Forcing

A new method for the estimation of oceanic mixed-layer depth using shipboard X-band radar images

2010 ◽  
Vol 28 (5) ◽  
pp. 962-967 ◽  
Author(s):  
Haibin Lü ◽  
Yijun He ◽  
Hui Shen ◽  
Limin Cui ◽  
Chang’e Dou
Keyword(s):  
Mixed Layer ◽  
Mixed Layer Depth ◽  
New Method ◽  
Layer Depth ◽  
Oceanic Mixed Layer ◽  
Radar Images ◽  
X Band

scholarly journals Exploration of the critical depth hypothesis with a simple NPZ model

2015 ◽  
Vol 72 (6) ◽  
pp. 1916-1925 ◽  
Author(s):  
Marina Lévy
Keyword(s):  
Mixed Layer ◽  
Mixed Layer Depth ◽  
Ecosystem Model ◽  
Model Solution ◽  
Critical Depth ◽  
Phytoplankton Blooms ◽  
Layer Depth ◽  
Seasonal Evolution ◽  
Physical Forcing ◽  
Surface Irradiance

Abstract The critical depth hypothesis (CDH) is a predictive criteria for the onset of phytoplankton blooms that comes from the steady-state analytical solution of a simple mathematical model for phytoplankton growth presented by Sverdrup in 1953. Sverdrup's phytoplankton-only model is very elementary compared with state-of-the-art ecosystem models whose numerical solution in a time-varying environment do not systematically conform to the CDH. To highlight which model ingredients make the bloom onset deviate from the CDH, the complexity of Sverdrup's model is incrementally increased, and the impact that each new level of complexity introduced is analysed. Complexity is added both to the ecosystem model and to the parameterization of physical forcing. In the most complete experiment, the model is a one-dimensional Nutrient-Phytoplankton-Zooplankton model that includes seasonally varying mixed layer depth and surface irradiance, light and nutrient limitation, variable grazing, self-shading, export, and remineralization. When complexity is added to the ecosystem model, it is found that the model solution only marginally deviates from the CDH. But when the physical forcing is also changed, the model solution can conform to two competing theories for the onset of phytoplankton blooms—the critical turbulence hypothesis and the disturbance recovery hypothesis. The key roles of three physical ingredients on the bloom onset are highlighted: the intensity of vertical mixing at the end of winter, the seasonal evolution of the mixed-layer depth from the previous summer, and the seasonal evolution of surface irradiance.

Impact of Explicit Atmosphere–Ocean Coupling on MJO-Like Coherent Structures in Idealized Aquaplanet Simulations

2006 ◽  
Vol 63 (9) ◽  
pp. 2289-2306 ◽  
Author(s):  
Wojciech W. Grabowski
Keyword(s):  
Mixed Layer ◽  
General Circulation ◽  
Large Scale ◽  
Mixed Layer Depth ◽  
Transfer Model ◽  
Quasi Equilibrium ◽  
Layer Depth ◽  
Oceanic Mixed Layer ◽  
Ocean Coupling ◽  
The Impact

Abstract This paper discusses the impact of the atmosphere–ocean coupling on the large-scale organization of tropical convection simulated by an idealized global model applying the Cloud-Resolving Convection Parameterization (CRCP; superparameterization). Because the organization resembles the Madden–Julian Oscillation (MJO), the results contribute to the debate concerning the role of atmosphere–ocean coupling in tropical intraseasonal oscillations. The modeling setup is an aquaplanet with globally uniform mean sea surface temperature (SST) of 30°C (tropics everywhere) in radiative–convective quasi equilibrium. The simulations apply an interactive radiation transfer model and a slab ocean model with a fixed oceanic mixed layer depth. Results from several 80- and 100-day-long simulations are discussed, where the only difference between the simulations is the prescribed oceanic mixed layer depth, which varied from 5 to 45 m. A simulation with a very deep oceanic mixed layer is also performed to represent constant-SST conditions. The simulations demonstrate that the interactive SST impedes the development of large-scale organization and has insignificant impact on the dynamics of mature MJO-like systems. The impediment is the result of a negative feedback between the large-scale organization of convection and SST, the convection–SST feedback. In this feedback, SST increases in regions of already suppressed convection and decreases in regions with enhanced convection, thus hindering the large-scale organization. Once developed, however, the MJO-like systems are equally strong in interactive and constant-SST simulations, and compare favorably with the observed MJO. The above impacts of the atmosphere–ocean coupling contradict the majority of previous studies using traditional general circulation models, where, typically, an enhancement of the intraseasonal signal occurs compared to prescribed-SST simulations. An explanation of this discrepancy is suggested.

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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