TY - JOUR

T1 - Some properties of tidal currents estimated from analytical and LES simulation studies

AU - Wakata, Yoshinobu

N1 - Funding Information:
Acknowledgments Drs. S. Raasch and J. Yoon are appreciated for helping in the use of PALM and for valuable discussions. Drs. Y. Yoshikawa and T. Endo also assisted with helpful discussions. This work was supported by JSPS KAKENHI Grant Number 22340140.

PY - 2013/12

Y1 - 2013/12

N2 - Some features of tidal current ellipses near the ocean floor are estimated from the bottom-limit solutions of the tidal equations with constant eddy viscosity. It is verified that a clockwise rotating ellipse becomes broad descending through the bottom boundary, whereas a counterclockwise ellipse becomes narrow except near the critical latitude. The major axis of an ellipse near the floor is directed 45° leftward (rightward) against that of the overlying tidal flow ellipse poleward from the critical latitude in the northern (southern) hemisphere. Equatorward from the critical latitude, the major axis near the floor lines up with that of the overlying tidal current ellipse in both hemispheres. The retrograde rotating hodograph against the overlying clockwise tidal hodograph appears near the floor around the critical latitude. These features are confirmed from the numerical studies using the large eddy simulation model. The deflection of the major axis poleward from the critical latitude is a little smaller, about 19°. Furthermore, the effects of nontraditional Coriolis force resulting from the horizontal component of the earth-rotating vector on the development of turbulence were investigated. When the diurnal tidal current is directed westward, the effective vertical eddy viscosity becomes maximum with developing turbulence. While in the case of a semidiurnal tide, a northward tidal current is preferred for turbulence development.

AB - Some features of tidal current ellipses near the ocean floor are estimated from the bottom-limit solutions of the tidal equations with constant eddy viscosity. It is verified that a clockwise rotating ellipse becomes broad descending through the bottom boundary, whereas a counterclockwise ellipse becomes narrow except near the critical latitude. The major axis of an ellipse near the floor is directed 45° leftward (rightward) against that of the overlying tidal flow ellipse poleward from the critical latitude in the northern (southern) hemisphere. Equatorward from the critical latitude, the major axis near the floor lines up with that of the overlying tidal current ellipse in both hemispheres. The retrograde rotating hodograph against the overlying clockwise tidal hodograph appears near the floor around the critical latitude. These features are confirmed from the numerical studies using the large eddy simulation model. The deflection of the major axis poleward from the critical latitude is a little smaller, about 19°. Furthermore, the effects of nontraditional Coriolis force resulting from the horizontal component of the earth-rotating vector on the development of turbulence were investigated. When the diurnal tidal current is directed westward, the effective vertical eddy viscosity becomes maximum with developing turbulence. While in the case of a semidiurnal tide, a northward tidal current is preferred for turbulence development.

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U2 - 10.1007/s10872-013-0204-6

DO - 10.1007/s10872-013-0204-6

M3 - Article

AN - SCOPUS:84888268823

VL - 69

SP - 737

EP - 751

JO - Journal of Oceanography

JF - Journal of Oceanography

SN - 0916-8370

IS - 6

ER -