GEOSC 040 Lecture Notes - Lecture 23: Amphidromic Point, Surf Zone, Oceanic Basin
Document Summary
Dynamic theory of tides- complexities of coastlines, bays, ocean basin geometry, earth deformation. Tides are shallow water waves, produced by gravity and centrifugal forces. A tide is a forced wave and must travel rapidly to keep up with the forcing. Tidal crests move in a counter clockwise pattern around the basins of the northern hemisphere. Rotary waves revolve around a fixed node. Resulting circulation is called an amphidromic circulation. Tidal crests move in a counter clockwise around basins of northern hemisphere. Earth has about 12: tidal amplitude increases progressively away from amphidromic points. Offshore zone- longshore bar, trough, but not always present. Foreshore zone- low tide terrace to berm crest: breaker zone- over longshore bar, waves begin to break, surf zone- wave energy dissipation, swash zone- wave swash at mean high tide. Inputs: longshore transport, river supply, cliff erosion, onshore transport. Outputs: longshore transport, offshore transport, wind transport to dunes. Caused by oblique angel of wave approach.
