X
3.7
3.8
3.9
3.10
3.11
Contents
Determination of the Recirculation
Homogenization of Potential Vorticity .......... .
Application of the Theory to the Subtropical Gyre ..
Quasi-Geostrophic Model
with Continuous Stratification ................ .
Numerical and Observational Evidence ......... .
124
131
136
References .................................. .
146
157
169
4
Theory of the Ventilated Thermocline . . . . . . . . . . . . 1 71
4.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
4.2 Formulation of the Model . . . . . . . . . . . . . . . . . . . 176
4.3 Midocean Approximations . . . . . . . . . . . . . . . . . . . 183
4.4 The Ventilated Thermocline: The Two-Layer Model . 188
4.5 The P-Spiral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
4.6 The Pool of Constant Potential Vorticity . . . . . . . . . 205
4.7 The Three-Layer Model . . . . . . . . . . . . . . . . . . . . . 207
4.8 The Subpolar Gyre . . . . . . . . . . . . . . . . . . . . . . . . . 216
4.9 Ventilation and Homogenization: A Unified Theory . 219
4.10 Effect of Finite Mixed Layer Depth . . . . . . . . . . . . . 233
4.11 Continuous Models of the Ventilated Thermocline . . 246
4.12 Observations and Numerical Models . . . . . . . . . . . . 262
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274
5
Buoyancy Forced Circulation and Cross-Gyre Flow . . . 277
5.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
5.2 Cross-Gyre Flow . . . . . . . . . . . . . . . . . . . . . . . . . . 279
5.3 Nonadiabatic Equations in Characteristic Form . . . . 292
5.4 The Buoyancy- and Wind-Driven Subtropical Gyre:
Analytical Solutions . . . . . . . . . . . . . . . . . . . . . . . . 308
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
6
Equatorial Dynamics of the Thermocline:
The Equatorial Undercurrent . . . . . . . . . . . . . . . . . . 321
6.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
6.2 Physics of the EUC: Preliminaries . . . . . . . . . . . . . . 329
6.3 An Inertial Theory of the Equatorial Undercurrent . . 334
6.4 The Nondissipative Model . . . . . . . . . . . . . . . . . . . 341
6.5 Role of the Shadow Zone
in the Undercurrent Structure . . . . . . . . . . . . . . . . . 355
6.6 Effect of Entrainment . . . . . . . . . . . . . . . . . . . . . . . 359
6. 7 Numerical Models . . . . . . . . . . . . . . . . . . . . . . . . . 368
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376