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SOAR 2005 Ocean Circulation and Heat Transport. Coriolis Force: All moving objects are deflected to their right in northern hemisphere to their left in.

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Presentation on theme: "SOAR 2005 Ocean Circulation and Heat Transport. Coriolis Force: All moving objects are deflected to their right in northern hemisphere to their left in."— Presentation transcript:

1 SOAR 2005 Ocean Circulation and Heat Transport

2 Coriolis Force: All moving objects are deflected to their right in northern hemisphere to their left in southern hemisphere

3 Tropical Cyclone Olyvia Hurricane Isabel Coriolis Force Northern Hemisphere  Moving objects deflected to their own right. Northern Hemisphere  Moving objects deflected to their own right. Southern Hemisphere  Moving objects deflected to their own left. L Storms rotate counterclockwise L Storms rotate clockwise

4 Energy Transfer Convection – hot stuff moves Conduction – hot stuff heats neighbors Radiation – heat moves as IR radiation Convection – hot stuff moves Conduction – hot stuff heats neighbors Radiation – heat moves as IR radiation

5 Properties of Water General properties  Stable (hard to tear apart)  Versatile solvent (universal solvent)  Polar properties  Give rise to surface tension  Capillary action  Responds to electric fields  Solid floats in the liquid  Ponds freeze on top, ice insulates water!  Water most dense as liquid at 4  C General properties  Stable (hard to tear apart)  Versatile solvent (universal solvent)  Polar properties  Give rise to surface tension  Capillary action  Responds to electric fields  Solid floats in the liquid  Ponds freeze on top, ice insulates water!  Water most dense as liquid at 4  C

6 Heat Properties of Water High latent heats  1 calorie = Joules High Heat Capacity  High energy gain/loss to change temperature High latent heats  1 calorie = Joules High Heat Capacity  High energy gain/loss to change temperature

7 Energy Transfer by Water Specific Heat  Energy absorbed or released to change temp. Specific Heat  Energy absorbed or released to change temp. SubstanceSpecific Heat (Joule/K/kg) Air (50  C)1050 Iron or Steel460 Lead130 Glass840 Quartz762 Granite804 Sandstone1088 Shale712 Soil (average)1050 Wood (average)1680 Ice2100 Steam2050 Water4168 Raising 1 kg of water 1°C absorbs 4,168 Joules 10 cm square cube of water 1 kg 4000 Joules ≈ energy to lift 400 kg or 900 lb 1 m

8 Energy Transfer by Water Latent Heat  Energy absorbed or released to change phase Latent Heat  Energy absorbed or released to change phase Evaporating 1 kg of water absorbs 2,257,000Joules 10 cm square cube of water 1 kg 2,257,000 Joules ≈ energy to lift 225,700 kg or 507,000 lb 1 m Substance Specific Heat (Joule/kg) vaporizationfusion Alcohol879,000109,000 Water2,257,000333,500

9 Energy Transfer by Water Latent heat effects weather Evaporating water absorbs energy from water, cooling it. Condensing water releases energy to air, heating it.

10 Energy Budget Insolation  Sun’s incident energy drives air motions (energy from deep interior adds a tiny bit)  Distribution of Sunlight  Reflection from clouds, landscape  Absorption by atmosphere  Absorption by surface  Albedo = ratio of sunlight reflected  Earth:  Moon:  Mars: 0.15  Venus: 0.84 Insolation  Sun’s incident energy drives air motions (energy from deep interior adds a tiny bit)  Distribution of Sunlight  Reflection from clouds, landscape  Absorption by atmosphere  Absorption by surface  Albedo = ratio of sunlight reflected  Earth:  Moon:  Mars: 0.15  Venus: 0.84

11 Insolation: 1,373 W/m 2 30% Reflected by atmosphere 20% Absorbed by atmosphere 50% Absorbed by Earth’s surface Most solar energy comes in as light (shortwave radiation)

12 Energy Flow from Surface 7% conducted to air 20% radiated as IR (longwave) % of total insolation 23% transferred by water

13 Energy Absorbed by Atmosphere 20% from Sun 7% conducted from surface 23% transferred by water 8% radiated by surface % of total insolation

14 Complete Energy Budget

15 Temperature Controls Sunlight heats land, water, air  Land warms, heats air  Air circulates  Convection cells  warms -> expands -> rises  cools -> contracts -> sinks  Water circulates  Currents driven by wind & Earth rotation  Water temperature increases SLOWLY  Large energy change needed for small temp. change Sunlight heats land, water, air  Land warms, heats air  Air circulates  Convection cells  warms -> expands -> rises  cools -> contracts -> sinks  Water circulates  Currents driven by wind & Earth rotation  Water temperature increases SLOWLY  Large energy change needed for small temp. change

16 Atmospheric Circulation Sunlight heats ground Ground heats air, drives convection from subsolar latitude Sunlight heats ground Ground heats air, drives convection from subsolar latitude Maximum Insolation Subsolar latitude is 23.5º N/S on the solstices Subsolar latitude is 0º on the equinoxes

17 Moist air rising  stormy Dry air falling  Arid

18 Pressure Zones Pressure Zones: air motion is vertical so there is little wind!

19 Wind Zones Winds named for direction they are from Westerlies NE Trades SE Trades Easterlies Doldrums Horse Latitudes Polar Front Windless zones names vary

20 Oceans’ Impact on Climate Most common compound on Earth  Covers 71% of surface area  Land area on Earth = surface on Mars  1.36 billion km 3 (326 million mk 3 )  70% of us by weight  Major constituent of most plants & animals Originated from  Outgasing of Volcanos (continues)  Bombardment by comets (much reduced)  Present volume established 2 by ago  Quantity in equilibrium Most common compound on Earth  Covers 71% of surface area  Land area on Earth = surface on Mars  1.36 billion km 3 (326 million mk 3 )  70% of us by weight  Major constituent of most plants & animals Originated from  Outgasing of Volcanos (continues)  Bombardment by comets (much reduced)  Present volume established 2 by ago  Quantity in equilibrium

21 Location of Water Southern Hemisphere  Moderates climate  Earth closest to sun in January (southern summer)  Antarctica surrounded  Strong winds, currents  Isolates Antarctic High  within “polar vortex”  Traps CFC’s, Destroys ozone Pacific Ocean  Covers ½ the Earth  Navigated by Polynesians and Chinese in ancient times? Southern Hemisphere  Moderates climate  Earth closest to sun in January (southern summer)  Antarctica surrounded  Strong winds, currents  Isolates Antarctic High  within “polar vortex”  Traps CFC’s, Destroys ozone Pacific Ocean  Covers ½ the Earth  Navigated by Polynesians and Chinese in ancient times? Mosaic of Antarctica from Galileo spacecraft Westerlies Easterlies

22 Location of Water Oceans 97.22%  Pacific48%4280 km(14 kft) deep  Atlantic28%3930(13 kft)  Indian20%3960(13 kft)  Arctic 4%1205( 4 kft) Oceans 97.22%  Pacific48%4280 km(14 kft) deep  Atlantic28%3930(13 kft)  Indian20%3960(13 kft)  Arctic 4%1205( 4 kft) Percentage of freshwater Percentage of surface water

23 Properties of Water Present as solid, liquid, gas on Earth  Gas & solid on Mars & most places  Solid and liquid (?) on Europa Polar molecule H 2 O  Oxygen  8 p +, 8 n o, 8e -  Hydrogen  1 p +, 1 e -  e - tend to hang around Oxygen Making that side negative Present as solid, liquid, gas on Earth  Gas & solid on Mars & most places  Solid and liquid (?) on Europa Polar molecule H 2 O  Oxygen  8 p +, 8 n o, 8e -  Hydrogen  1 p +, 1 e -  e - tend to hang around Oxygen Making that side negative

24 Surface Currents Mapped by rubber duckies, bottles

25 World Surface Currents Driven by wind, Coriolis, continents Distribute heat from equator toward poles Driven by wind, Coriolis, continents Distribute heat from equator toward poles

26 Surface Currents: Pacific Kuro Siwo warm current to north North Pacific Drift brings warm water eastward California current brings cold water south Some flow into arctic ocean Oya Siwo: cold current soutward past Asia East Australian warm current to south West Wind Drift circles Antarctcia Cold Peruvian current brings fish toward shore

27 Surface Currents: Atlantic West Wind Drift dominates south Atlantic currents Gulf Stream feeds North Atlantic Drift, dominates north Atlantic currents COLD Labrador current drives subsurface currents Brazilian & Benguela currents circle south Atlantic COLD Canaries current past Africa

28 Gyres: Circular Currents Turning and turning in the widening gyre The falcon cannot hear the falconer; Things fall apart; the centre cannot hold; William Butler Yeats, The Second Coming North Atlantic Gyre

29 Gyres Circular currents Eckman transport “mounds” water  pushes water  to surface current  Coriolis deflection balances gravity Circular currents Eckman transport “mounds” water  pushes water  to surface current  Coriolis deflection balances gravity Sea Level isn’t level!

30 Sea Level Sea level varies due to  changes in local gravity (subsurface structure)  currents (Eckman transport) Mean Sea Level  Monitored by satellites Sea level varies due to  changes in local gravity (subsurface structure)  currents (Eckman transport) Mean Sea Level  Monitored by satellites High Low Residuals = departure from normal Click for Quicktime Movie of Sea surface height and temperature.

31 Regional Surface Currents Equatorial Currents  Drive upwelling in east, spreading in west Equatorial Currents  Drive upwelling in east, spreading in west Currents driven by trade winds Water leaving shore pulls water up from below: upwelling Water deflects N & S due to continents & Coriolis

32 Slackened trade winds allow warm water to slosh east, stopping upwelling of nutrient- rich water Regional Current Variations ENSO – El Niño Southern Oscillation  Trade winds & equatorial currents slacken ENSO – El Niño Southern Oscillation  Trade winds & equatorial currents slacken Normal trade winds push warm surface water to Asia allowing upwelling of cold, nutrient-rich, water near South America

33 Currents & Ocean Life Nutrients  compounds of nitrogen, silicon, phosphorous  minerals  carried by upwelling cold water Phytoplankton  Fish food (bottom of the food chain)  CO 2 sink (absorb ½ Earth’s CO 2 )  Some toxic (algae blooms, “red tides”) Fish  Prefer living in warmer water Best fishing where cold & warm water meet!  eg. The Outer Banks Nutrients  compounds of nitrogen, silicon, phosphorous  minerals  carried by upwelling cold water Phytoplankton  Fish food (bottom of the food chain)  CO 2 sink (absorb ½ Earth’s CO 2 )  Some toxic (algae blooms, “red tides”) Fish  Prefer living in warmer water Best fishing where cold & warm water meet!  eg. The Outer Banks

34 El Niño building … El Niño fading … ENSO Trigger unknown Sea Surface Temperature monitored for signs of building El Niño Trigger unknown Sea Surface Temperature monitored for signs of building El Niño

35 Regional Current Variations PDO – Pacific Decadal Oscillation  Discovered in 1996 by Steven Hare researching connection between Alaska Salmon & Pacific climate  Warm (+) = Warm equatorial waters In positive phase since April 2001  Cool (-) = Warm water at high latitudes PDO – Pacific Decadal Oscillation  Discovered in 1996 by Steven Hare researching connection between Alaska Salmon & Pacific climate  Warm (+) = Warm equatorial waters In positive phase since April 2001  Cool (-) = Warm water at high latitudes

36 Regional Current Variations PDO – Pacific Decadal Oscillation  Currently in Positive phase (since April 2001)  Fisheries in northeast pacific very productive PDO – Pacific Decadal Oscillation  Currently in Positive phase (since April 2001)  Fisheries in northeast pacific very productive

37 Regional Current Variations Gulf Stream  Keeps Europe warm!!  Drives worldwide currents Gulf Stream  Keeps Europe warm!!  Drives worldwide currents

38 Deep Ocean Currents Thermohaline circulation  Density of sea water  increases with salinity  decreases with temperature  Evaporation  decreases water surface temperature  increases salinity  Gulf Stream  warm surface water evaporates in N. Atlantic cools, increases salinity ⇒ sinks to bottom Thermohaline circulation  Density of sea water  increases with salinity  decreases with temperature  Evaporation  decreases water surface temperature  increases salinity  Gulf Stream  warm surface water evaporates in N. Atlantic cools, increases salinity ⇒ sinks to bottom Cold, salty water sinks to bottom. Warm surface water gets colder and saltier than subsurface water.

39 North Atlantic Downwelling Gulf Stream  Bring warm water north … keep Europe warm!  Cools, salinates, sinks, pulling more north Gulf Stream  Bring warm water north … keep Europe warm!  Cools, salinates, sinks, pulling more north

40 North Atlantic Downwelling Gulf stream waters sink to bottom  Flow South along ocean bottom  Drives Deep water circulation Gulf stream waters sink to bottom  Flow South along ocean bottom  Drives Deep water circulation

41 Deep Ocean Circulation Great Conveyor Belt moving HEAT  circuit takes about 2000 years Great Conveyor Belt moving HEAT  circuit takes about 2000 years

42 Deep Ocean Circulation Great Conveyor Belt moving HEAT  circuit takes about 2000 years Great Conveyor Belt moving HEAT  circuit takes about 2000 years

43 Deep Ocean Circulation Great Conveyor Belt moving HEAT  circuit takes about 2000 years Great Conveyor Belt moving HEAT  circuit takes about 2000 years

44 Ocean Conveyor Belt Can shut Down with too much fresh water

45 Thermohaline Shutdown? 13,400 years ago Lake Iroquois drained through lake Champlain and Hudson Valley into Atlantic Jeffrey Donnelly, WHOI, December 2004, “Catastrophic Flooding from Ancient Lake May Have Triggered Cold Period ”WHOICatastrophic Flooding from Ancient Lake May Have Triggered Cold Period

46 Thermohaline Shutdown? 13,300 years ago Lake Candona formed from remnant of Lake Iroquois Jeffrey Donnelly, WHOI, December 2004, “Catastrophic Flooding from Ancient Lake May Have Triggered Cold Period ”WHOICatastrophic Flooding from Ancient Lake May Have Triggered Cold Period

47 Thermohaline Shutdown? 13,100 years ago Lake Candona increases as glacier continues retreating Jeffrey Donnelly, WHOI, December 2004, “Catastrophic Flooding from Ancient Lake May Have Triggered Cold Period ”WHOICatastrophic Flooding from Ancient Lake May Have Triggered Cold Period

48 Thermohaline Shutdown? 13,000 years ago Lake Candona drains through St. Lawrence Valley, seawater intrudes as Champlain Sea Jeffrey Donnelly, WHOI, December 2004, “Catastrophic Flooding from Ancient Lake May Have Triggered Cold Period ”WHOICatastrophic Flooding from Ancient Lake May Have Triggered Cold Period

49 Thermohaline Shutdown Gulf Stream stops warming Europe  Europe cools dramatically Gulf Stream stops warming Europe  Europe cools dramatically Lake Iroquois draining through Hudson Valley: Intra-Alleroid Cold Period Lake Candona draining through St. Lawrence Valley: Younger Dryas

50 Ocean Changes Temperature rising  Cause of more and more powerful hurricanes? Temperature rising  Cause of more and more powerful hurricanes? The oceans have absorbed about 30 times more heat than the atmosphere since 1955 Oceans 18.2 x J Atmosphere 6.6 x J CurryCurry, WHOI, OCCI The oceans have absorbed about 30 times more heat than the atmosphere since 1955 Oceans 18.2 x J Atmosphere 6.6 x J CurryCurry, WHOI, OCCI

51 Ocean Changes Salinity  Decreasing in north Atlantic Salinity  Decreasing in north Atlantic cf. Curry, WHOI, OCCICurry

52 Ocean Changes Salinity  Decreasing at high latitude  Increasing at low latitude Salinity  Decreasing at high latitude  Increasing at low latitude “ … deep waters have become less salty in critical North Atlantic locations, where salty, dense waters sink to drive the global ocean circulation system... ”

53 Ocean Changes Salinity  Decreasing at high latitude  Increasing at low latitude Salinity  Decreasing at high latitude  Increasing at low latitude “Global warming may be intensifying evaporation, adding more fresh water vapor to the atmosphere and leaving tropical oceans relatively saltier.”


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