Midterm #1 results posted early next week see BlackBoard Answer Keys for both White and Blue exams will be provided on course website Scantrons 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? 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? FThe 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 F Sound is transmitted better in water than it is in air F Sound velocity in the ocean is about 1500 m/s, or about 4 times its speed in air F Sound velocity increases with pressure and temperature

SOFAR Sound Channel FSound is focused into the SOFAR channel because it is a low velocity region FSound is transmitted best through this channel -- good for whales and submarines (e.g., Hunt for Red October) FSound is focused into the SOFAR channel because it is a low velocity region FSound 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 èUneven heating of Earths surface èRelease of heat as infrared radiation èRequires flow of heat by oceans and atmosphere èSurface circulation èUneven heating of Earths surface èRelease of heat as infrared radiation èRequires flow of heat by oceans and atmosphere èSurface circulation

Global Heat Budget heat at the Earth's surface (342 W/m 2 ) is supplied by absorption of short-wave solar radiation from the sun. heat lost from Earth is through long-wave radiation back to space. heat at the Earth's surface (342 W/m 2 ) is supplied by absorption of short-wave solar radiation from the sun. heat lost from Earth is through long-wave radiation back to space.

The Greenhouse Effect FThe Atmosphere is transparent to sunlight (ultraviolet [UV] and visible) FClouds absorb or reflect about half FSunlight heats the Earths surface, which then radiates energy as longer wavelength energy (infrared) FThis energy is trapped by the atmospheric gases (CO 2, H 2 O, CH 4 ) FThe Atmosphere is transparent to sunlight (ultraviolet [UV] and visible) FClouds absorb or reflect about half FSunlight heats the Earths surface, which then radiates energy as longer wavelength energy (infrared) FThis energy is trapped by the atmospheric gases (CO 2, H 2 O, CH 4 )

Special Properties of Water FRECALL: 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) Seasonal changes in temperature profile

Temperature (vertical profile) Cool drinks go here Thermocline

Temperatures with Depth FThermocline -- sharp temperature change

Evaporation - Precipitation FOver the oceans, evaporation exceeds precipitation FThe balance is restored by rain over the continents, returning water via rivers FOver the oceans, evaporation exceeds precipitation FThe balance is restored by rain over the continents, returning water via rivers

Evaporation vs Precipitation

Climate Belts

Ocean Surface Salinity

Salinity Variations

FSurface salinity follows evaporation- precipitation pattern FAtlantic Ocean is generally more salty than Pacific Ocean, in spite of river input -- why?? FSurface salinity follows evaporation- precipitation pattern FAtlantic Ocean is generally more salty than Pacific Ocean, in spite of river input -- why??

Isthmus of Panama èNet transfer of fresh water from Atlantic to Pacific

Salinity of Rivers and Ocean Water Cant 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. SiO 2

Residence Time Flux has units of mass per unit time Reservoir has units of mass R/F has units of time

Density of Sea Water (Where does Oregons seawater plot?)

Bottom Water Oregons ocean

Density Rules!

Where does the Oceans Deepest Water Come From? FThe densest seawater is COLD and SALTY FThis is formed at high latitudes in the North and South Atlantic: North Atlantic Deep Water (NADW) Antarctic Bottom Water (AABW) FCould dense seawater form in the tropics? (evaporation!) FThe densest seawater is COLD and SALTY FThis is formed at high latitudes in the North and South Atlantic: North Atlantic Deep Water (NADW) Antarctic Bottom Water (AABW) FCould dense seawater form in the tropics? (evaporation!)

Dissolved Gases in the Ocean

Important Gases in the Ocean FOxygen -- Respiration, Decomposition FCO 2 -- Photosynthesis, CaCO 3 FNitrogen -- Nutrient for growth (NO 3 ) FMethane -- a product of decomposition FOxygen -- Respiration, Decomposition FCO 2 -- Photosynthesis, CaCO 3 FNitrogen -- Nutrient for growth (NO 3 ) FMethane -- a product of decomposition

Photosynthesis and Respiration FBiology interacts with the Chemistry

Dissolved Oxygen

Biochemical Recycling

Summary: Biochemical Cycles FElements enter oceans through rivers FGases enter oceans thru air-sea boundary FBiology alters distribution of elements (nutrients) and gases FOcean circulates nutrients to surface, but only in a few places (called upwelling) FInteraction of physics, chemistry and biology => geological record (sediments) FElements enter oceans through rivers FGases enter oceans thru air-sea boundary FBiology alters distribution of elements (nutrients) and gases FOcean circulates nutrients to surface, but only in a few places (called upwelling) FInteraction of physics, chemistry and biology => geological record (sediments)