Geography and Oceanography - Chapter 11 pot

How is sound transmitted in the ocean?. Light Absorption in WaterIntensity decreases rapidly with depth Blue and green penetrate deepest, giving the ocean its color... Ocean Temperature

Midterm #1 results posted early next week

see BlackBoard

Answer Keys for both White and Blue exams

will be provided on course websiteScantrons will be returned in labs next week

Physical and Chemical Structure of the Ocean

Why are the oceans blue?

How is sound transmitted in the ocean?

Why is the ocean “layered” in many locations?How do you keep your beer cool in the tropics?

Light Absorption in Water

Intensity decreases rapidly with depth

Blue and green penetrate deepest, giving the ocean its color

Why do objects lose their

color with depth?

✦The colors other than blue (and

green) are absorbed by the water

molecules in the first few meters only blue (and green) are reflected

Sound in Sea Water

✦ Sound is transmitted better in water than

SOFAR Sound Channel

✦Sound is focused into the SOFAR channel because it is a low velocity region

✦Sound is transmitted best through this

channel good for whales and submarines(e.g., “Hunt for Red October”)

Heard Island Experiment

Global Warming faster velocity??

Go to Sounds

Ocean Temperature Solar Heating

➨Uneven heating of Earth’s surface

➨Release of heat asinfrared radiation

➨Requires flow of

heat by oceans andatmosphere

➨Surface circulation

Global Heat Budget

 heat at the Earth's

The Greenhouse Effect

✦The Atmosphere is transparent to

sunlight (ultraviolet [UV] and visible)

✦Clouds absorb or reflect about half

✦Sunlight heats the Earth’s surface, which then radiates energy as longer wavelength energy (infrared)

✦This energy is trapped by the atmospheric gases (CO2, H2O, CH4)

Special Properties of Water

✦ RECALL:

Melting and boiling points are very high

Highest heat capacity of common liquids

High heat of fusion and vaporization

Sea Surface Temperatures

only 0°-30°C world-wide

Land:

50°C to -50°C

Local Annual Heat Budgets

 Amount of solar energy captured at one location

on the Earth varies with season

Local Annual Heat Budgets

 Amount of solar energy captured at one location

on the Earth varies with season

Where we live

Temperature (vertical profile)

Seasonalchanges in temperature profile

Temperature (vertical profile)

Cool drinks go here

Thermocline

Temperatures with Depth

✦Thermocline sharp temperature change

Evaporation vs Precipitation

Climate Belts

Ocean Surface Salinity

Salinity Variations

Salinity Variations

✦Surface salinity follows

evaporation-precipitation pattern

✦Atlantic Ocean is generally more salty

than Pacific Ocean, in spite of river input why??

Salinity of Rivers and Ocean Water

Can’t just concentrate

river water to get

seawater

How do we explain this

observation?

Rivers Ocean

Concept of Residence Time

Each element removed

from ocean in different

ways

And at different rates

e.g Cl - vs SiO2

Density of Sea Water

(Where does Oregon’s seawater plot?)

Density of Sea Water

(Where does Oregon’s seawater plot?)

Bottom Water Oregon’s ocean

Density Rules!

Where does the Ocean’s Deepest Water Come From?

✦The densest seawater is COLD and SALTY

✦This is formed at high latitudes in the

North and South Atlantic:

North Atlantic Deep Water (NADW)

Antarctic Bottom Water (AABW)

✦Could dense seawater form in the tropics?

(evaporation!)

Dissolved Gases in the Ocean

Important Gases in the Ocean

✦Oxygen Respiration, Decomposition

✦CO2 Photosynthesis, CaCO3

✦Nitrogen Nutrient for growth (NO3)

✦Methane a product of decomposition

Photosynthesis and Respiration

✦Biology interacts with the Chemistry

Dissolved Oxygen

Biochemical Recycling

Summary: Biochemical Cycles

✦Elements enter oceans through rivers

✦Gases enter oceans thru air-sea boundary

✦Biology alters distribution of elements

(“nutrients”) and gases

✦Ocean circulates nutrients to surface, but only in a few places (called “upwelling”)

✦Interaction of physics, chemistry and

biology => geological record (sediments)