Oceanography Unit Ch. 13-14-15

Earth is often referred to as the blue planet Surface Area of the Planet (510,066,000 sq..

km) Seventy-one percent of Earth’s surface is

represented by oceans and marginal seas (361,419,000 sq.. km) 70.9%

Continents and islands comprise the remaining 29 percent. (148,647,000 sq. km) 29.1%

Northern Hemisphere is called the land hemisphere, and the Southern Hemisphere the water hemisphere

13.1 The vast world ocean

Views of the Northern and Southern Hemispheres

The vast world ocean

Spanning over an area of ~65.3 million square miles, is the largest among the various oceans of the world.

It makes up a third of the total surface, and half of the total water surface of the planet.

In fact, it is larger than all the continents of the world put together.

At the Equator, the Pacific Ocean stretches for a distance of 11,000 miles, which is almost half way around the planet.

Pacific Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions.

With a total area of about 41,100,000 sq. mi, it covers approximately 20 percent of the Earth's surface and about 29 percent of its water surface area.

The first part of its name refers to Atlas of Greek mythology, making the Atlantic the "Sea of Atlas

World’s youngest ocean and contains the Earth’s largest mountain range.

Atlantic Ocean

The Indian Ocean is the third largest of the world's five oceans.

Total area is ~26,024,836 million sq. mi. about 6 times the size of the US

Location: body of water between Africa, the Southern Ocean, Asia, and Australia

Indian Ocean

The Arctic Ocean is the smallest and shallowest of the five oceanic divisions in the world, to be found in the Northern Hemisphere and mainly in the Arctic North Polar Region.

Throughout the year, the ocean is largely covered with a sheet of sea ice due to very low temperatures.

The Arctic Ocean is nearly completely surrounded by Eurasia and North America.

Like Antarctica, the Arctic Ocean lacks the fabled history The Arctic Ocean is less than 1.5 times the size of the

United States of America and has a total area of 8.7 million sq.. mi.

Every summer, the ice caps are surrounded by open seas, but double in size during winter and blanket the entire ocean.

Arctic Ocean

A decision by the International Hydrographic Organization in the spring of 2000 delimited a fifth world ocean - the Southern Ocean

The Southern Ocean extends from the coast of Antarctica north to 60 degrees south latitude, which coincides with the Antarctic Treaty Limit.

The Southern Ocean is now the fourth largest of the world's five oceans Covers an area roughly two times that of the US

Total area: ~7848295 sq. mi

Southern Ocean

The oceans of Earth

PROPERTIES OF SEA WATER Phase Changes Density Salinity Effect of salinity on physical properties

ENERGY TRANSMISSION/ABSORPTION IN WATER AND SEA WATER Heat Light Sound

Properties of Ocean Water

–Evap. of sea water --> water vapor in atmosphere

•Cools the ocean•Heat energy transferred to

water vapor–Condensation of water vapor: Principle source for warming the atmosphere“Latent Heat” in the atmosphere

Importance of H2O phase changes

How much energy is needed to heat up a substance...OR How efficiently heat is stored in a substance

Definition: "Energy required to raise the temperature of one gram of the substance by 1°C.”

HEAT CAPACITY (= specific heat)

1 calorie / g - °C ... very high!• Rocks and soils = 0.2 cal. / g - °C.

•Consequences of this difference...–Oceans and lakes gain/lose much heat with little temperature (T) change–Land heats and cools much more easily

WATER HAS A LARGE HEAT CAPACITY

In general..– Warmer = less dense– Cooler = denser

•Maximum density at 4°C•Cooling from 4°C to 0°C make water EXPAND

Fresh Water Lakes during winter cooling- Surface freezes at 0°C- Coldest water, and ice, DO NOT sink

- Bottom stays at 4°C and does not freeze --good for fish!

HOW DOES TEMPERATURE AFFECT T

DENSITY OF PURE WATER?

Salinity - - amt. of dissolved salts; symbol = S

•Average S = 35 g/kg (p.p.t, o/oo)•Range of S (99% of all sea water) =

30 -37 o/oo•Addition of salts increases densityDissolved salts change physical properties of sea water.

–Boiling point = 103°C–Freezing point lowered...

How does salty water differ from pure water?

-- Sea water begins to freeze at -2°C; salt is excluded from the ice crystals.-- Remaining water is saltier, freezes at lower T.

-Brine Solution•Seawater gets denser as it gets colder, all the way to the freezing point (unlike fresh water)-- Higher density causes sinking of coldest sea water (unlike lake water!)

Freezing :

... increases as S increases.

... increases as T decreases.Very important! Remember convection:•Dense water found at the ocean surface (in someareas) SINKS-Where are these areas found?

- Poles •“Deep water” masses form in these areas because of:... cooling (T decreases)... freezing & evaporation (S increases)•These sink until they reach water of the same density,then spread out

Density of Seawater

15.1 Ocean water movements

Surface circulation Ocean currents are masses of water that flow

from one place to another Driven by uneven heating of the surface by the

Sun Surface currents develop from friction between

the ocean and the wind that blows across the surface

Huge, slowly moving gyres

Ocean water movements

Surface circulation Five main gyres

North Pacific Gyre South Pacific Gyre North Atlantic Gyre South Atlantic Gyre Indian Ocean Gyre

Related to atmospheric circulation

Global surface circulation

The world population has jumped to over 7million people and the amount of freshwater needed for survival is limited. Read box 14.1 and research methods used to desalinize seawater.

Write a persuasive essay convincing the government to support or not support an increase in desalinization here in the US. Be sure to include the impact that desalinization may have on the Earth System.

Desalinization

Ocean water movements Surface circulation

Deflected by the Coriolis effect To the right in the Northern Hemisphere To the left in the Southern Hemisphere Coriolis Demos Merry-go-round: http://

www.youtube.com/watch?v=mcPs_OdQOYU Uganda: http://www.youtube.com/watch?v=Pb69HENUZs8

Four main currents generally exist within each gyre

Importance of surface currents Climate

Currents from low latitudes into higher latitudes (warm currents) transfer heat from warmer to cooler areas

Ocean water movements

Surface circulation Importance of surface currents

Climate Influence of cold currents is most pronounced in the

tropics or during the summer months in the middle latitudes

Upwelling The rising of cold water from deeper layers Most characteristic along west coasts of continents Brings greater concentrations of dissolved nutrients

to the ocean surface

Deep Water Currents Thermohaline Circulation Ocean circulation transports surface seawater to the

polar region where it cools. This cooling releases heat which warms the air and makes the water cold and, therefore, dense enough to sink to the bottom of the ocean.

This results in the formation of new deep water which displaces existing deep water pushing it towards the equator. The major regions for this deep water formation are the Labrador and Greenland Seas in the northern North Atlantic Ocean.

This North Atlantic Deep Water then flows south along the ocean floor allowing more warm surface water to flow into the region to replace it. Strong cooling also occurs in the Bering Sea in the North Pacific, but the structure of the ocean floor here prevents the deep water that forms from entering the ocean circulation.

Ocean Water Movement

15.2 The coastal zone

The land-sea boundary Shoreline – contact between land and sea Shore – area between lowest tidal level and

highest areas affected by storm waves Coastline – the seaward edge of the coast Beach – accumulation of sediment along the

landward margin of the ocean

The coastal zone

Classification of marine organisms

Plankton: Most of Earth’s biomass Animals (zooplankton) Plant (phytoplankton)

Recent estimate suggest that phytoplankton is responsible for 70-80% of the oxygen produced.

Bacteria According to recent studies one liter of ocean water contains

~20,000 different species of bacteria. Nekton

All animals capable of moving independently of the ocean currents

They are unable to move throughout the breath of the ocean

Benthos Bottom dwellers A great number of species exist on the shallow coastal floor Most live in perpetual darkness in deep water

Ocean life: Marine life zones Several factors are used to divide the ocean into

distinct marine life zones Availability of Sunlight Distance from shore Water Depth

Ocean life: Availability of Light

Ocean life: Distance from Shore

Ocean life: Water Depth

Marine life zones

Ocean water movements

Waves Energy traveling along the interface between

ocean and atmosphere Derive their energy and motion from wind Parts

Crest Trough

Ocean water movements

Waves Measurements of a wave

Wave height – the distance between a trough and a crest

Wavelength – the horizontal distance between successive crests (or troughs)

Wave period – the time interval for one full wave to pass a fixed position

Ocean water movements Waves

Wave height, length, and period depend on Wind speed Length of time the wind blows Fetch – the distance that the wind travels

As the wave travels, the water passes energy along by moving in a circle Waveform moves forward At a depth of about one-half the wavelength, the

movement of water particles becomes negligible (the wave base)

Changes that occur when a wave moves onto shore