Lecture 7: Coastal Oceanography

Question 1

Global ocean bathymetry

Answer 1

• 72% of globe is ocean
• Much of the ocean bottom
  is flat
• Coastal ocean (Continental
  shelf) is 10% of ocean area
• Continental shelf (0 - 150 m
  depth) is land during ice
  ages

Question 2

Are coastal regions more or less productive than the open ocean

Answer 2

• Coastal regions are highly productive (3 to 5 times more productive than open
  ocean)
• Coastal oceans support majority of the world’s fisheries (up to 90%)

Question 3

Describe the anatomy of the coastal ocean.

Answer 3

• Coastal ocean is a transition between
  terrestrial and abyssal environments
• Coastal ocean is characterized by physical gradients (ocean bottom, hydrodynamics, water properties)

Question 4

Describe features and consequences of coastal environments

Answer 4

• Sandy vs. rocky nearshore:
  Sediment and breaking waves
• Inlets, canyons, headlands:
  Coastline and bathymetric variation
• Coral reefs:
  Shallow platforms, steep slope
• Estuaries and Fjords:
  Freshwater input

Physical gradients means that processes are visible!

Question 5

What is a wave?

Answer 5

“A wave is a signal or disturbance transferred from one part of a
medium to another with a recognizable speed of propagation.

Question 6

What propagates away in a wave?

Answer 6

A wave mostly transfers energy through a
medium with minimal material transport.

Question 7

Describe the following terminology for waves, Crest, trough, wave height, wave length, wave period, wave phase.

Answer 7

• Crest: highest point on wave
• Trough: lowest point on wave
• Wave height H: vertical distance
  between crest and trough
  (Amplitude a: half of height)
• Wavelength L: distance between
  adjacent wave crests or troughs
  Snapshot in time Time stack
• Wave Period T:
  time between arrival of successive wave
  crests or troughs at a single location
• Wave (phase) speed Cp= L/T
  This definition of Cp is valid for any kind of wave

Question 8

What creates a wave in the ocean?

Answer 8

Disturbance:
sea surface is displaced by winds or pressure

Restoring Force:
gravity

Propagation:
pressure gradients due to different water heights

Question 9

Review slide 14 on deep water vs shallow water waves

Answer 9

yeeeeeeeeeeeee

Question 10

Compare deep water vs shallow water waves.

Answer 10

Deep vs. shallow water waves

• In deep water ( h / L > 0.5 ), Cp varies with wavelength
• Longer waves travel faster (dispersive)
• In shallow water ( h / L < 0.05 ), Cp depends only on depth.
• All waves travel at the same speed
  (non-dispersive)