Chapter 5. SPATIALLY-COHERENT STRUCTURES
c
shear
conv
shear
e
f
Q
Q
Q
Q
|
,
(5.35)
where
0
shear
u h
Q
N ,
1/ 3
1/ 6
0
/
1 30
cos
cos
c
conv
shear
h
Ri
f
L
Q
Q
I
I
N
ª
º
|
«
»
¬
¼
is
the factor describing convective enhancement of mixing in the frontal zone,
L is the width of the frontal interface,
2
2
0
0
/
/
Ri g h u
c u
c
, c 0 is the
phase speed of internal disturbances,
u is the friction velocity in water, N is
von Karman’s constant (N = 0.4), I the wind direction relative to the
direction of buoyant spreading of the front. For I > 90
o or I < -90
o and
1
{
c
f
, no convective instability is possible (Stommel’s overturning gate is
opened), while for –90
o < I < 90
o and
1
c
f ! convective instability at the
leading edge of the gravity current can develop (Stommel’s overturning gate
is closed).
Incorporation of parameterization (5.35) into (5.34) leads to the
339
following relationship:
Figure 5-35. Diagram for the two regimes of wind-front interaction according to (5.36) –(5.37).
Reproduced from Soloviev et al. (2002) by permission from Elsevier.