218
7 Ocean Currents
the details of the vertical structure of current velocities u and v. Instead, he
developed relationships for the total transport in the x and y directions in the
whole layer affected by wind action (Kamenkovitch, 1978; Pond and Pickard,
1983; Whitehead, 1995):
(7.25)
Equation (7.25) is known as the Sverdrup equation in which My is the total
transport in the y direction, T is the wind stress at the sea surface, {3 = of / oy,
and:
(7.26)
is the vertical component of the curl of the wind stress (for definition of curl,
see Appendix C).
Sverdrup's extension of the Ekman theory gains the possibility of having a
coastal boundary at one side of the ocean, which is a step towards a more
realistic situation compared to Ekman's boundless ocean. The details of Sverdrup's theory are beyond the scope of this book. The interested reader should
consult some of Sverdrup's papers (Sverdrup, 1945, 1947) or Pond and Pickard
(1983) for an in-depth discussion.
Langmuir Circulation. Persistent winds blowing across the sea surface may
induce small-scale vertical water motion. Langmuir (1938) observed that when
~I
.. lO-50m
convergence
divergence
level of no motion
downwelling
(2-6 cmls)
t
upwelling
(1-2 cmls)
convergence
Fig. 7.8: Langmuir circulation (adapted from Pinet, 1992)
7 Ocean Currents
the details of the vertical structure of current velocities u and v. Instead, he
developed relationships for the total transport in the x and y directions in the
whole layer affected by wind action (Kamenkovitch, 1978; Pond and Pickard,
1983; Whitehead, 1995):
(7.25)
Equation (7.25) is known as the Sverdrup equation in which My is the total
transport in the y direction, T is the wind stress at the sea surface, {3 = of / oy,
and:
(7.26)
is the vertical component of the curl of the wind stress (for definition of curl,
see Appendix C).
Sverdrup's extension of the Ekman theory gains the possibility of having a
coastal boundary at one side of the ocean, which is a step towards a more
realistic situation compared to Ekman's boundless ocean. The details of Sverdrup's theory are beyond the scope of this book. The interested reader should
consult some of Sverdrup's papers (Sverdrup, 1945, 1947) or Pond and Pickard
(1983) for an in-depth discussion.
Langmuir Circulation. Persistent winds blowing across the sea surface may
induce small-scale vertical water motion. Langmuir (1938) observed that when
~I
.. lO-50m
convergence
divergence
level of no motion
downwelling
(2-6 cmls)
t
upwelling
(1-2 cmls)
convergence
Fig. 7.8: Langmuir circulation (adapted from Pinet, 1992)