MB L3 Handouts

8/13/2019 MB L3 Handouts

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1

Many processes regulate the composition of seawater. Theconcept of a steady state ocean utilizes the idea that ionsare added to and removed from the ocean at the same rate.

2Residence Time

Reactivity determines how long various dissolvedions stay within the ocean

Residence Time: The average time spent by asubstance in the Ocean

=

Amount in Sea

Rate entering or exiting



5

Conservative constituents of seawater are thoseconstituents that occur in constant proportions. Conservativeelements have long residence times and are the mostabundant dissolved material in the ocean.

Nonconservative constituents have short residence times,and are usually associated with seasonal, biological or shortgeological cycles.

Conservative and NonconservativeConstituents

6Dissolved Gases

• Dissolved gases are required for life in the ocean.• Gas dissolves more readily in cold water than it does

on warm water • Some dissolved gases are conservative constituents

in seawater, others are nonconservative constituents.



10Light Absorption in Water

11

Why is the Ocean Blue?

• Absorbtion• Scattering• Reflection



12

The relationship between water depth and sound velocity.

Sound in the Ocean

Sound velocity inair ~340 m/sec

14SOFAR Sound Channel

• Sound is transmitted more effectively and rapidly inwater than it is in air

• Sound velocity in the ocean is about 1500 m/s, orabout 4-5 times that in air

• Sound is focused into the SOFAR channel because of

its low velocity region• Sound is transmitted best through this channel --important for submarines and cetaceans



15

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17

Note that the pH of seawater varies slightly with depth.

pH of Seawater

average pH ofseawater is 8.0

18

A quick taste of the carboncycle which buffers the pHof seawater.



19

Thermostatic properties – those properties of water thatact to moderate changes in temperature

Thermostatic inertia - the tendency of a substance toresist change in temperature with the gain or loss of heatenergy

Global Thermostatic Effects

20Seasonal Sunlight

Winter

Summer



23World Water Vapor

24Evaporation - Precipitation

Over the oceans, evaporation exceeds precipitation

The balance is restored by rain over the continents,returning water via rivers



25Sea-Surface Salinity

26Evaporation vs. Precipitation



27Temperature, Salinity, & Density

28Temperature, Salinity, & Density



29

30Water and Climate



31

The unique thermal properties of water are responsible forthe mild conditions on Earth. Water’s thermostatic effectsallow living things to flourish on Earth.

32Ocean Climate Regions



33Temperature Vertical Structure

34Temperatures with Depth

Thermocline -- sharp temperature change



35

The ocean is d ivided intothree density zones:

The surface zone - the upper

layer of the ocean, containingthe least dense water. Thesurface zone is only about 2%of total ocean volume.

The pycnocline - a zone inwhich density increases withdepth, containing about 18% ofall ocean water

The deep zone – containsabout 80% of all ocean water.There is little change in densitythroughout this layer.

Density Structure of the Ocean

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37

Physical Oceanography 101

38Heat Budget



39Global Air Circulation

40

A large circuit of air is called an atmosphericcirculation cell. Three cells exist in each hemisphere.

Hadley cells are tropical cells found on each side of theequator.

Ferrel cells are found at the mid-latitudes.

Polar cells are found near the poles.

The Wind: Atmospheric Circulation Cells



41

What are some of the wind patterns found betweenand within cells?

The doldrums are calm equatorial areas where twoHadley cells converge

The horse latitudes are areas between Hadley andFerrel cells. There is little surface wind in this area.

The trade winds are surface winds of Hadley cells.

The westerlies are surface winds of Ferrel cells.

Wind Patterns

42The Coriolis Effect

The Coriolis effect is the observed deflection of amoving object, caused by the moving frame of referenceon the spinning Earth.

How does this apply to the atmosphere?

As air warms, expands, and ascends at the equator, itmoves toward the pole, but instead of traveling in astraight path, the air is deflected eastward.

In the Northern Hemisphere air turns to the right.

In the Southern Hemisphere air turns to the left.



43Coriolis Effect

44Coriolis

QuickTime Movie



45The Coriolis Effect

Air moves in cells, influenced by the Coriolis effect.

46Wind Patterns



47

* Ocean water circulates in currents.

* Surface currents are caused mainly by wind , and affect theuppermost 10% of the ocean.

* Circulation of the other 90% of the ocean is driven by gravity,as dense water sinks and less dense water rises.

* Upwelling and downwelling describe the vertical movement ofwater masses.

* The Coriolis effect modifies the course of ocean currents.

Ocean Circulation : summary

48Ocean Circulation

The westerlies and the trade winds are two of the winds thatdrive the ocean’s surface currents.



49Ocean Currents

What are some effects of ocean currents?

Ocean currents:• transfer heat from tropical to polar regions• influence weather and climate• distribute nutrients and scatter organisms

50Ocean Currents

• Surface currents Affect surface water within and above the pycnocline (10%of ocean water)Driven by major wind belts of the world

• Deep currents Affect deep water below pycnocline (90% of ocean water)Driven by density differencesLarger and slower than surface currents



51Surface Currents

Most of Earth’s surface wind energy is concentrated in theeasterlies and westerlies.

Due to the forces of gravity, the Coriolis effect, solarenergy, and solar winds, water often moves in a circularpattern called a gyre.

52Surface Currents

Water moves clockwisein the NorthernHemisphere gyres andcounterclockwise in theSouthern Hemispheregyres.

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