1. Across Channel Momentum Balancey z
LNM h1 h2
Geostrophic balance (frictionless, steady and linear motion) in the lower layer

2. h z h1 LNM y h2 Geostrophic Balance in the upper layer
Geostrophic Balance in the lower layer:

3. y z
LNM h1 h2 h
Margules’ Relation
How about ?
With one can determine

4. Effects of the Earth’s Rotation

6. Observed slope: 2m in 10 km
2 / 104 = 2 x 10-4
f = 8.8e-5
u1 = 0.08
u2 =
rho1 = 1020
rho2 = 1024

8. Could you draw the pressure field (isobars) associated with these salinity (density) fields?
u1 = 0.10 m/s
u2 = m/s
ρ1 = 1017 kg/m3
ρ2 = 1022 kg/m3
f = 8.8 e-5 s-1
Observed =
2 m in 8 km =
2.5 x 10-4
u1 = 0.08 m/s
u2 = m/s
ρ1 = 1021 kg/m3
ρ2 = 1023 kg/m3
f = 8.8 e-5 s-1
Observed =
7 m in 8 km =
8.8 x 10-4

10. Internal Radius of Deformation Internal Rossby Radius
Generally, the outflow modified by rotation will be restricted by the
internal radius of deformation R, derived from geostrophy:
Scaling: L
Internal Radius of Deformation or
Internal Rossby Radius

13. Framework established:
Along estuary: pressure gradient balanced by friction
Across estuary: geostrophic balance

14. S0