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Physics

003b. Physics. Seawater Physics. Temperature Light Sound Buoyancy Dissolved gasses Waves Tides. Temperature. Isotherms. polar. 60 o. temperate. 30 o. 0 o. tropic. 30 o. temperate. 60 o. polar. Lines of equal temperature. Sea Surface Temperature. Oct. 2010.

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Physics

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  1. 003b Physics

  2. Seawater Physics • Temperature • Light • Sound • Buoyancy • Dissolved gasses • Waves • Tides

  3. Temperature

  4. Isotherms polar 60o temperate 30o 0o tropic 30o temperate 60o polar Lines of equal temperature

  5. Sea Surface Temperature Oct. 2010

  6. Sea Surface Temperature

  7. Sea Surface Temperature 10-24-10 to 10-27-2010

  8. Temperature SalinityDensity Low High Low High Low High surface 0 m 200 m 1000 m thermocline halocline pycnocline Thermocline + Halocline = Pycnocline

  9. Properties of Light in the Ocean

  10. The Electromagnetic Radiation Spectrum Only green and blue wavelengths pass through water a great distance.

  11. Light Absorption in the Ocean • Light Intensity • decreases with depth • 0-200 m (photic zone) • 200-1000m (dysphotic zone) • >1000 (aphotic zone)

  12. Light Penetration in the Ocean Wavelength (nm) 400 500 600 700 0 m Photic Zone Photosynthesis 200m No Photosynthesis Dysphotic Zone 1000m Aphotic Zone ~65% of visible light is absorbed in the 1st m

  13. Light effects organisms residing in the photic and aphotic zone. • Phytoplankton productivity • Algae- green, brown, red • Predator/Prey relationships • Diurnal vertical migration • Bioluminescence- luminescent organs on underside mimic downwelling light

  14. Sound in Water

  15. Sound in Water Speed of sound- faster in ocean (higher density) 1500 m/sec, which is 4x faster than in air Difficult to determine direction of sound Can hear many things such as ships miles away, shrimp eating, helicopters overhead, and whales communicating. source of noise

  16. Speed of Sound (m/sec) 1,475 1,500 0 1000 2000 3000 4000 high speed min speed sofar layer Depth (m) high speed

  17. SOFAR Channel Distance 0 500 1000 1500 2000 sound rays Depth (m) SOFAR channel

  18. Sofar Layer The depth at which the speed of sound is minimum; Thus, loud noises can be heard for thousands of km Sound generated by Navy test in Indian Ocean at sofar layer was heard as far away as the Oregon coast. May affect behavior and anatomy of marine organisms

  19. Organisms adaptation to buoyancy in water • Blubber • Swim bladder • Pneumatophore

  20. Organisms adaptation to buoyancy in water • Air chambers • Large liver & heterocercal tail • Buoyancy Compensator Device (BCD)

  21. Dissolved Gasses in Seawater

  22. Solubility of Gases in Seawater as a Function of Temperature (salinity @ 33o/oo) Solubility (ml/l at atmospheric pressure) Temperature N2 O2 CO2 (oC) . 0 14.47 8.14 8,700 10 11.59 6.42 8,030 20 9.65 5.26 7,350 30 8.26 4.41 6,660 Zebra ‘Tidepool’ Blenny

  23. Relationship between water depth, pressure, and volume Air weighs 14 lbs/in2 (psi) Absolute pressure is the combined pressure of water and air Depth 0 ft 33 ft 66 ft 99 ft Absolute Pressure 1 atm 14.7 psi 2 atm 29.4 psi 3 atm 44.1 psi 4 atm 58.8 psi Volume x1 x 1/2 x 1/3 x 1/4

  24. Boyle’s Law For any gas at a constant temperature, the volume will vary inversely with absolute pressure while the density will vary with absolute pressure. I.e., volume  with  pressure  pressure  density

  25. Henry’s Law When a mixture of gas is in contact w/a liquid, each gas will dissolve in the liquid in proportion to its partial pressure. Gasses can go in and out of solution e.g., open soda, get CO2 bubbles (CO2 is under pressure)

  26. Dissolved gasses in seawater: Seawater Air N2 48% 78% O2 36% 21% CO2 15% 0.04% Gasses dissolve most readily in cold water

  27. Decompression sickness It is caused when N2 enters the blood circulation and the tissues. When extra N2 leaves the tissues, large bubbles form. N2 bubbles can travel throughout the system and into the lungs and blood routes. Treatment: hyperbaric chamber

  28. O2 Minimum Zone (OMZ)

  29. O2 Content (ml/L) Water depth (m)

  30. What causes the O2 minimum layer? Marine snow

  31. Why are there high levels of O2 at depth?

  32. O2 Dead Zones

  33. Surface currents are wind driven currents

  34. Ekman Transport Water flow in the Northern hemisphere- 90o to the right of the wind direction Depth is important

  35. Upwelling and downwelling • Vertical movement of water () • Upwelling = movement of deep water to surface • Hoists cold, nutrient-rich water to surface • Produces high productivities and abundant marine life • Downwelling = movement of surface water down • Moves warm, nutrient-depleted surface water down • Not associated with high productivities or abundant marine life

  36. upwelling downwelling

  37. Langmuir Circulation

  38. Tides are generated by: • Gravitational pull of the moon and sun • Centripetal force of the rotating Earth

  39. Tides are generated by: • the gravitational pull of the moon and sun • - moon has 2x greater gravitational pull than the • sun • - sun is 10 million x more massive than the • moon and is 390 times farther away

  40. Centripetal force

  41. GRAVITATIONAL FORCE CENTRIPETAL GRAVITATIONAL & CENTRIPETAL

  42. Tidal Cycles • Diurnal Tide: 24 hr 50 min cycle • Semi DiurnalTide: 12 hr 25 min cycle • Mixed Tide: 12 hr 25 min cycle

  43. Description of tides • High water: a water level maximum ("high tide") • Low water: a water level minimum ("low tide") • Tidal range: the difference between high and low tide • Spring Tide: full moon and new moon (14.77 days) • Neap Tide: 1st quarter and 3rd quarter (14.77 days) Intertidal zone High tide Low tide

  44. The monthly tidal cycle(29½ days) • About every 7 days, Earth alternates between: • Spring tide • Alignment of Earth-Moon-Sun system • Lunar and solar bulges constructively interfere • Large tidal range • Neap tide • Earth-Moon-Sun system at right angles • Lunar and solar bulges destructively interfere • Small tidal range

  45. Earth-Moon-Sun positions and the monthly tidal cycle Spring Tide Highest high tide and lowest low tide Neap Tide Moderate tidal range

  46. Tidal Range 56 ft 6 ft

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