Elements of P
15
Part A | 2.1
2. Elements of Physical Oceanography
Wendell S. Brown
This chapter discusses the most important elements of physical oceanography in terms of the
various oceanic responses to atmospheric and astronomical forcing – as mediated by earth rotation,
including surface, and internal gravity waves; inertial motion and hurricane-driven storm surge.
We include an outline of the history of windgenerated surface waves: generation to dissipation
on the beaches. The roles of turbulence-derived
oceanic friction in Ekman dynamics/upwellingdownwelling are outlined. There is a discussion of
the elements of practical tidal sea level prediction.
There is a review of the central role of geostrophic
flow in wind- and thermohaline-driven circulations on ocean basin as well as continental shelf
scales.
2.1 Atmospheric Processes ............................ 16
2.2 Ocean Structure....................................... 17
2.3 Oceanic Processes.................................... 18
2.4 Surface Gravity Waves ............................. 19
2.4.1 Surface Gravity Waves ..................... 19
2.4.2 Definitions .................................... 20
2.4.3 Wave Generation and Evolution ...... 25
2.5 Wind-Forced Ocean Processes .................. 28
2.5.1 Frictional Effects ............................ 28
2.5.2 Earth Rotation Effects ..................... 29
2.5.3 Hurricane Wind-Forced Ocean
Response ...................................... 29
2.5.4 Wind-Forced Upper Ocean Response
with Earth Rotation Effects ............. 33
2.5.5 Wind-Driven Currents:
Ocean Basin Scale .......................... 34
2.5.6 Gulf Stream Ring Flows ................... 37
2.6 Deep Ocean Currents ............................... 38
2.7 Coastal Ocean Currents ............................ 39
2.8 Ocean Surface Tides................................. 40
2.9 Oceanic Internal Waves and Tides ............ 43
References..................................................... 45
The ocean environment consists not only of the water column, but also the atmosphere above the water’s
surface and the seafloor and sediment and rocks of
the subseafloor. A comprehensive study of the marine
environment is enormous in scope and is thus often
subdivided into disciplinary components, including biology, chemical, geology, physics, and meteorology.
This chapter will focus on basic introductory information concerning aspects of the marine environment;
however, it will also refer oceanographic literature for
those seeking more comprehensive treatments.
Different aspects of ocean engineering design are
influenced to varying degrees by one or more environmental factors. These factors comprise one of
the several groups of the so-called external design
constraints; or constraints that are independent of
or external to the purpose on which the design is
based. For example, submersibles encounter temperature, salinity, pressure, and density gradients as they
move through the water column, irrespective of their
individual missions. These external constraints may
be subdivided into those which are fixed by mission requirements and those which are variable. For
example, the design maximum operating depth of
a submersible sets the maximum pressure that the
submersible can encounter. However, this operating
constraint is not usually linked to specific values of
sea water temperature, salinity, and density which
can be encountered; but rather only ranges of these
variables.
While discussing different oceanic environmental
factors, it is convenient to consider them in terms of the
three basic regimes in a vertical profile that includes the
atmosphere and the water column.
15
Part A | 2.1
2. Elements of Physical Oceanography
Wendell S. Brown
This chapter discusses the most important elements of physical oceanography in terms of the
various oceanic responses to atmospheric and astronomical forcing – as mediated by earth rotation,
including surface, and internal gravity waves; inertial motion and hurricane-driven storm surge.
We include an outline of the history of windgenerated surface waves: generation to dissipation
on the beaches. The roles of turbulence-derived
oceanic friction in Ekman dynamics/upwellingdownwelling are outlined. There is a discussion of
the elements of practical tidal sea level prediction.
There is a review of the central role of geostrophic
flow in wind- and thermohaline-driven circulations on ocean basin as well as continental shelf
scales.
2.1 Atmospheric Processes ............................ 16
2.2 Ocean Structure....................................... 17
2.3 Oceanic Processes.................................... 18
2.4 Surface Gravity Waves ............................. 19
2.4.1 Surface Gravity Waves ..................... 19
2.4.2 Definitions .................................... 20
2.4.3 Wave Generation and Evolution ...... 25
2.5 Wind-Forced Ocean Processes .................. 28
2.5.1 Frictional Effects ............................ 28
2.5.2 Earth Rotation Effects ..................... 29
2.5.3 Hurricane Wind-Forced Ocean
Response ...................................... 29
2.5.4 Wind-Forced Upper Ocean Response
with Earth Rotation Effects ............. 33
2.5.5 Wind-Driven Currents:
Ocean Basin Scale .......................... 34
2.5.6 Gulf Stream Ring Flows ................... 37
2.6 Deep Ocean Currents ............................... 38
2.7 Coastal Ocean Currents ............................ 39
2.8 Ocean Surface Tides................................. 40
2.9 Oceanic Internal Waves and Tides ............ 43
References..................................................... 45
The ocean environment consists not only of the water column, but also the atmosphere above the water’s
surface and the seafloor and sediment and rocks of
the subseafloor. A comprehensive study of the marine
environment is enormous in scope and is thus often
subdivided into disciplinary components, including biology, chemical, geology, physics, and meteorology.
This chapter will focus on basic introductory information concerning aspects of the marine environment;
however, it will also refer oceanographic literature for
those seeking more comprehensive treatments.
Different aspects of ocean engineering design are
influenced to varying degrees by one or more environmental factors. These factors comprise one of
the several groups of the so-called external design
constraints; or constraints that are independent of
or external to the purpose on which the design is
based. For example, submersibles encounter temperature, salinity, pressure, and density gradients as they
move through the water column, irrespective of their
individual missions. These external constraints may
be subdivided into those which are fixed by mission requirements and those which are variable. For
example, the design maximum operating depth of
a submersible sets the maximum pressure that the
submersible can encounter. However, this operating
constraint is not usually linked to specific values of
sea water temperature, salinity, and density which
can be encountered; but rather only ranges of these
variables.
While discussing different oceanic environmental
factors, it is convenient to consider them in terms of the
three basic regimes in a vertical profile that includes the
atmosphere and the water column.