An approximate solution of wave-modified Ekman current for gradually varying eddy viscosity

2011 ◽  
Vol 58 (6) ◽  
pp. 668-676 ◽  
Author(s):  
Jin-Bao Song ◽  
Yan-Song Huang
Keyword(s):  
Approximate Solution ◽  
Eddy Viscosity ◽  
Ekman Current

scholarly journals Wave-Modified Ekman Current Solutions for the Time-Dependent Vertical Eddy Viscosity

2021 ◽  
Vol 9 (6) ◽  
pp. 664
Author(s):  
Hui Chen ◽  
Shaofeng Li ◽  
Jinbao Song ◽  
Hailun He
Keyword(s):  
Eddy Viscosity ◽  
Time Variability ◽  
Surface Shear ◽  
Near Surface ◽  
Depth Dependence ◽  
Temporal Averaging ◽  
Low Level Jet ◽  
Mean Current ◽  
Ekman Current ◽  
Vertical Eddy

This study aimed to highlight a general lack of clarity regarding the scale of the temporal averaging implicit in Ekman-type models. Under the assumption of time and depth-dependent eddy viscosity, we present an analytical Fourier series solution for a wave-modified Ekman model. The depth dependence of eddy viscosity is based on the K-Profile Parameterization (KPP) scheme. The solution reproduces major characteristics of diurnal variation in ocean velocity and shear. Results show that the time variability in eddy viscosity leads to an enhanced mean current near-surface and a decrease in the effective eddy viscosity, which finally results in an intensified near-surface shear and wakes a low-level jet flow. Rectification values are dominated by the strength of diurnal mixing, and partly due to the nonlinear depth dependence of the eddy viscosity.

scholarly journals Can Drake Passage Observations Match Ekman's Classic Theory?

2013 ◽  
Vol 43 (8) ◽  
pp. 1733-1740 ◽  
Author(s):  
Jeff A. Polton ◽  
Yueng-Djern Lenn ◽  
Shane Elipot ◽  
Teresa K. Chereskin ◽  
Janet Sprintall
Keyword(s):  
Eddy Viscosity ◽  
Acoustic Doppler Current Profiler ◽  
Drake Passage ◽  
Surface Boundary ◽  
Surface Boundary Layer ◽  
Sampling Distributions ◽  
Classic Theory ◽  
Current Profiler ◽  
Depth Scale ◽  
Ekman Current

Abstract Ekman's theory of the wind-driven ocean surface boundary layer assumes a constant eddy viscosity and predicts that the current rotates with depth at the same rate as it decays in amplitude. Despite its wide acceptance, Ekman current spirals are difficult to observe. This is primarily because the spirals are small signals that are easily masked by ocean variability and cannot readily be separated from the geostrophic component. This study presents a method for estimating ageostrophic currents from shipboard acoustic Doppler current profiler data in Drake Passage and finds that observations are consistent with Ekman's theory. By taking into account the sampling distributions of wind stress and ageostrophic velocity, the authors find eddy viscosity values in the range of 0.08–0.12 m2 s−1 that reconcile observations with the classic theory in Drake Passage. The eddy viscosity value that most frequently reconciles observations with the classic theory is 0.094 m2 s−1, corresponding to an Ekman depth scale of 39 m.

INCREASE OF HEAT TRANSFER AND NEGATIVE EDDY VISCOSITY IN TURBULENT FLOWS INFLUENCED BY A MAGNETIC FIELD

1990 ◽  
Author(s):  
C. Henoch ◽  
Martin Hoffert ◽  
A. Baron ◽  
D. Klaiman ◽  
Semion Sukoriansky ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Turbulent Flows ◽  
Eddy Viscosity

Approximate Solution of One Dynamic Problem of Geoinformatics

2010 ◽  
Vol 42 (5) ◽  
pp. 1-11 ◽  
Author(s):  
Vladimir M. Bulavatskiy ◽  
Vasiliy V. Skopetsky
Keyword(s):  
Approximate Solution ◽  
Dynamic Problem

On Improved Approximate Solution of the Fredholm Integral Equation

2006 ◽  
Vol 6 (3) ◽  
pp. 264-268
Author(s):  
G. Berikelashvili ◽  
G. Karkarashvili
Keyword(s):  
Integral Equation ◽  
Approximate Solution ◽  
Fredholm Integral Equation ◽  
Algebraic Equations ◽  
Order Convergence ◽  
One Dimensional ◽  
Averaging Operator ◽  
Linear Algebraic Equations ◽  
Convergence Solution

AbstractA method of approximate solution of the linear one-dimensional Fredholm integral equation of the second kind is constructed. With the help of the Steklov averaging operator the integral equation is approximated by a system of linear algebraic equations. On the basis of the approximation used an increased order convergence solution has been obtained.

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