Physical Oceanography

Question 1

% of water that the ocean holds
ice
ground water

Answer 1

97.6–> 137010^6km3
2.1
0.5
rest <0.001

Question 2

Unique properties of seawater

Answer 2

High heat capacity- raise temp of 1g by 1degrees

greater solvent power than any other substance

Question 3

Why is temperature important

Answer 3

reflects
the amount of heat held and transported by
the ocean.

Question 4

temperature range in ocean

Answer 4

-2–28

Question 5

The temperature of the ocean is primarily

influenced by

Answer 5

the heating at the air-sea

interface

Question 6

define thermocline

Answer 6

a steep temperature gradient in a body of water such as a lake, marked by a layer above and below which the water is at different temperatures

Question 7

Salinity

Answer 7

Total dissolved solids (mainly sodium chloride,
or “table salt”)
- About 3.5% by weight (average seawater)
- Usually expressed as 35 0/00 (parts per
thousand, ppt or practical salinity units, psu)
- Varies geographically according to
Evaporation, precipitation, rivers, ice
formation and ice melt.

Question 8

Evaporation versus precipitation

Answer 8

evaporation generally exceeds precipitation
The balance is restored by rain over the
continents, returning water via rivers

Question 9

Define halocline

Answer 9

a well-defined vertical salinity gradient in ocean or other saline water.

Question 10

define density (p)

Answer 10

Density is the mass of sea water per unit volume.

Question 11

Density depends on

Answer 11

Density depends on salinity, temperature and
pressure.
- Density increases with increasing salinity
- Density increases with decreasing temperature
• Seawater density ranges from 1021 – 1070 kg/m³
,
the average density is 1025 kg/m³
increases with pressure

Question 12

lighter water is

Answer 12

• warmer
• less saline
• shallower

Question 13

denser water is

Answer 13

colder
• more saline
• deeper

Question 14

define pycnocline

Answer 14

layer in an ocean or other body of water in which water density increases rapidly with depth

Question 15

NADW

AABW

Answer 15

North Atlantic Deep Water

Antarctic Bottom Water

Question 16

3 defining characteristics of GFD

Answer 16

Geophysical Fluid Dynamics
aspect
ratio, stratification, and rotatio

Question 17

Oceans aspect ratio is large or small

Answer 17

large
horizontal/ vertical scale
like a piece of paper

Question 18

The Coriolis force (rotation force)

Answer 18

• acts at right-angles to the actual direction
of water motion.
• causes water to move to the right in the
northern hemisphere
• causes water to move to the left in the
southern hemisphere.

Question 19

How do surface winds drag the ocean

Answer 19

friction

Question 20

surface winds are

Answer 20

a source of energy for the ocean

Question 21

The extent to which the wind drags the surface

water depends on:

Answer 21

• wind strength
• wave conditions
• density stratification

Question 22

give an example of an energy sink

Answer 22

friction- causes mixing in the ocean

Question 23

Interior friction

Answer 23

depends on the density and the

currents

Question 24

•Bottom friction

Answer 24

depends on the bottom currents

and the bottom roughness

Question 25

Ocean pressure

Answer 25

``` is the weight of seawater per unit area mainly a function of depth Pressure in the ocean increases at a rate of about 1 “atmosphere” per 10 m of water ```

Question 26

Pressure=

Answer 26

Height*density*g

Question 27

Pressure gradient force

Answer 27

occurs when there is a horizontal pressure difference | high to low p

Question 28

Explain Ekman transport

Answer 28

• When the wind blows on the ocean, the wind drags the surface layer with it. • Rotation causes the surface layer to deflect to the right (NH) and move at 45o to the wind direction. • Interior friction causes the surface layer to drag on the layer below. • Rotation causes this layer to again deflect to the right (NH). • The resulting currents are called Ekman transport

Question 29

geostrophic balance and the | resulting current is referred to as a geostrophic current

Answer 29

• Suppose we have a difference in sea-level height. Water will be accelerated from the region of high pressure towards the region of low pressure. • As the water starts to move, the Coriolis effect (rotation) deflects the water to the right (NH) or left (SH). • The water keeps getting deflected until the force due to the pressure difference balances the Coriolis force.

Question 30

Most of earth's surface wind energies is concentrated in

Answer 30

the easterlies and westerlies

Question 31

Gyre

Answer 31

Due to wind-generated pressure differences and the Coriolis effect water typically moves in a circular pattern

Question 32

effects of ocean currents

Answer 32

transfer heat from tropical to polar regions •influence weather and climate •distribute nutrients

Question 33

Upwelling

Answer 33

refers to the process where deeper, colder, and potentially nutrient-rich water is brought to the surface

Question 34

Why is upwelling important

Answer 34

it uplifts nutrients to depths where there is light (recall that both light and nutrients are needed for photosynthesis to occur). more nutrients at greater depth

Question 35

Equatorial upwelling

Answer 35

The winds are predominantly easterly (or westward) along the Equator. • In the southern hemisphere the Ekman transport is to the left of the wind. • In the northern hemisphere the Ekman transport is to the right of the wind. • This corresponds to a divergence in the Ekman transport at the equator and results in equatorial upwelling

Question 36

Wind-driven coastal upwelling

Answer 36

In coastal regions, when the wind blows parallel to the coast the Ekman transport is either directed onshore or offshore. • When the Ekman transport is offshore, upwelling results. • The offshore Ekman transport is “balanced” by an onshore flow below the surface Ekman layer. • As a result, colder water is uplifted to the surface. • When the Ekman transport is onshore, downwelling results. This is the opposite to upwelling

Question 37

Spring Tides

Answer 37

``` Occur When the Moon Pulls along the same Line as the Sun. (new and full moon). ```

Question 38

Neap Tides

Answer 38

``` Occur When the Moon Pulls at 90o to the Sun (first and last quarter moon) ```

Question 39

Tidal waves

Answer 39

have wavelengths (L) on the order of 1/2 the diameter of the earth or about 20,000 km. • Since the ocean is about 4km deep, and since L/20 is about 1000km, tidal waves are shallow water waves

Question 40

What are waves (4 points)

Answer 40

A wave transfers a disturbance from one part of a material to another 2. The disturbance is propagated through the material without any substantial overall motion of the material itself. 3. The disturbance is propagated without any significant distortion of the wave form. 4. The disturbance appears to be propagated with constant speed (unless fluid depth is shallow and changing).

Question 41

what is being transported by a wave

Answer 41

energy

Question 42

Surface waves

Answer 42

Waves which occur at an interface (wind raindrops earthquakes) Generating force = Restoring force

Question 43

Surface waves on water--> 2 restoring forces?

Answer 43

Gravitational force | surface tension

Question 44

Pressure in the vertical & buoyancy | Archimedes principle:

Answer 44

the upthrust force = the weight of water displaced

Question 45

capillary waves

Answer 45

For waves with wavelengths less than about 1.7 cm, the principal restoring force is surface tension

Question 46

Gravity Waves

Answer 46

Travel On Density Surfaces

Question 47

Wave Speed

Answer 47

(length of wave) / (wave period)

Question 48

The period of a wave remains the same

Answer 48

(determined by generating force)

Question 49

Wave trains

Answer 49

packets of similar waves with approximately the same | period and speed

Question 50

Wave refraction

Answer 50

close to the shoreline. Waves approaching shore at an angle first “feel bottom” close to shore, slowing them down there and causing waves to align themselves to the coastline

Question 51

As a wave breaks, the energy it received from the wind is | dissipated.- where does it go

Answer 51

ØSome energy is reflected back out to sea. ØMost of the energy is dissipated as heat and sound (the ‘roar’ of the surf) in the final small-scale mixing of foaming water, sand and shingle. ØSome energy is used in fracturing large rock or mineral particles into smaller ones. ØSome energy is used to move sediments.