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Extra Credit #3. May 2 (Monday), 7:30pm Byrne Lecture Dr. Eddie Bernard, NOAA “Tsunamis” Austin Auditorium LaSells Stewart center 1-page reaction paper to your TA. Reminder:.
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Extra Credit #3 • May 2 (Monday), 7:30pmByrne LectureDr. Eddie Bernard, NOAA“Tsunamis”Austin AuditoriumLaSells Stewart center1-page reaction paper to your TA
Reminder: • Interviews with instructors must be completed by this Friday (April 29)Dr. Wright’s office hours are:MW 1:50-3pm or just before classDr. Duncan’s office hours are:MWF 3-4pm in COAS Admin Bldg
Physical and Chemical Structure of the Ocean Why are the oceans blue? How do you keep your beer cool in the tropics?
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 it is in air • Sound velocity in the ocean is about 1500 m/s, or about 4 times its speed in air
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
Heard Island Experiment • Global Warming -- faster velocity??
Solar Heating • Uneven heating of Earth’s surface • Release of heat asinfrared radiation • Requires flow ofheat by oceans andatmosphere
Global Heat Budget • heatat the Earth's surface (342 W/m2) 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 • 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 highHighest heat capacity of common liquidsHigh heat of fusion and vaporization
Sea Surface Temperaturesonly 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
Temperature (vertical profile) Beer goes here
Temperatures with Depth • Thermocline -- sharp temperature change
Evaporation - Precipitation • Over the oceans, evaporation exceeds precipitation • The balance is restored by rain over the continents, returning water via rivers
Chemistry of River and Ocean Water • Can’t just concentrate river water to get seawater • How do we explain this observation?
Concept of Residence Time • Each element removed from ocean in different ways • And at different rates • e.g. Cl- vs. SiO2
Residence Time F has units of mass per unit time R has units of mass R/F has units of time
Salinity Variations • Surface salinity follows evaporation-precipitation pattern • Atlantic Ocean is generally more salty than Pacific Ocean, in spite of river input -- why??
Isthmus of Panama • Net transfer offresh waterfrom Atlanticto Pacific
Density of Sea Water(Where does Oregon’s seawater plot?) o *
Density of Sea Water(Where does Oregon’s seawater plot?) Oregon’s ocean o Bottom Water *
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!)
Important Gases in the Ocean • Oxygen -- Respiration, Decomposition • CO2 -- Photosynthesis, CaCO3 • Nitrogen -- Nutrient for growth • Methane -- a product of decomposition
Photosynthesis and Respiration • Biology interacts with the Chemistry
Summary: Biochemical Cycles • Nutrients enter oceans through rivers • Gases enter oceans thru air-sea boundary • Biology alters distribution of nutrients and gases • Circulation returns nutrients to surface • Interaction of physics, chemistry and biology => geological record (sediments)