SOAR 2005 Ocean Circulation and Heat Transport. Coriolis Force: All moving objects are deflected to...

SOAR 2005SOAR 2005

Ocean Circulation and Heat Transport

Ocean Circulation and Heat Transport

Coriolis Force:Coriolis Force: All moving objects are deflected

All moving objects are deflected

to their right in

northern hemisphere

to their right in

northern hemisphere

to their left in southern hemisphere

to their left in southern hemisphere

Tropical Cyclone OlyviaTropical Cyclone Olyvia

Hurricane IsabelHurricane Isabel

Coriolis ForceCoriolis 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.

Southern Hemisphere Moving objects

deflected to their own left.

L

Storms rotate counterclockwise

Storms rotate counterclockwise

L

Storms rotate clockwise

Storms rotate clockwise

Energy TransferEnergy 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

Properties of WaterProperties 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 4C

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 4C

Heat Properties of WaterHeat Properties of Water High latent heats

1 calorie = 4.186 Joules

High Heat Capacity High energy gain/loss to change temperature

High latent heats 1 calorie = 4.186 Joules

High Heat Capacity High energy gain/loss to change temperature

Energy Transfer by WaterEnergy Transfer by Water Specific Heat

Energy absorbed or released to change temp.

Specific Heat Energy absorbed or released to change temp.

Substance Specific Heat (Joule/K/kg)

Air (50C) 1050

Iron or Steel 460

Lead 130

Glass 840

Quartz 762

Granite 804

Sandstone 1088

Shale 712

Soil (average) 1050

Wood (average)

1680

Ice 2100

Steam 2050

Water 4168

Raising 1 kg of water 1°C

absorbs 4,168 Joules

Raising 1 kg of water 1°C

absorbs 4,168 Joules

10 cm square cube

of water

10 cm square cube

of water

1 kg

4000 Joules ≈ energy to lift 400 kg or 900 lb 1 m4000 Joules ≈ energy to lift 400 kg or 900 lb 1 m

Energy Transfer by WaterEnergy 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 2,257,000Joule

s

Evaporating 1 kg of water

absorbs 2,257,000Joule

s 10 cm square cube

of water

10 cm square cube

of water

1 kg

2,257,000 Joules ≈ energy to lift 225,700 kg or 507,000 lb 1 m2,257,000 Joules ≈ energy to lift 225,700 kg or 507,000 lb 1 m

Substance

Specific Heat (Joule/kg)

vaporization

fusion

Alcohol 879,000 109,000

Water 2,257,000 333,500

Energy Transfer by WaterEnergy Transfer by Water Latent heat effects weather Latent heat effects weather

Evaporating water absorbs energy

from water, cooling it.

Evaporating water absorbs energy

from water, cooling it.

Condensing water releases energy to

air, heating it.

Condensing water releases energy to

air, heating it.

Energy BudgetEnergy 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: 0.367 Moon: 0.113 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: 0.367 Moon: 0.113 Mars: 0.15 Venus: 0.84

Insolation: 1,373 W/m2Insolation: 1,373 W/m2

30% Reflected by atmosphere

30% Reflected by atmosphere

20% Absorbed by atmosphere

20% Absorbed by atmosphere

50% Absorbed by Earth’s surface

50% Absorbed by Earth’s surface

Most solar energy comes in as light (shortwave

radiation)

Most solar energy comes in as light (shortwave

radiation)

Energy Flow from SurfaceEnergy Flow from Surface7% conducted to air7% conducted to air

20% radiated as

IR (longwave)

20% radiated as

IR (longwave)

% of total insolation% of total insolation

23% transferred by water23% transferred by water

Energy Absorbed by Atmosphere

Energy Absorbed by Atmosphere

20% from Sun20% from Sun7% conducted from surface7% conducted from surface

23% transferred by water23% transferred by water8% radiated by

surface8% radiated by surface

% of total insolation% of total insolation

Complete Energy BudgetComplete Energy Budget

Temperature ControlsTemperature 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

Atmospheric CirculationAtmospheric 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 23.5º

N/S on the solstices

Subsolar latitude is 0º on the equinoxes

Subsolar latitude is 0º on the equinoxes

Moist air rising stormy




Dry air falling Arid




Pressure ZonesPressure Zones

Pressure

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

Pressure

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

Wind ZonesWind ZonesWinds named

for direction they are

from

Winds named

for direction they are

from

WesterliesWesterlies


NE TradesNE Trades

SE TradesSE Trades

EasterliesEasterlies


Doldrums

Horse Latitudes

Horse Latitudes

Polar Front

Polar Front

Windless zones names vary

Windless zones names vary

Oceans’ Impact on ClimateOceans’ Impact on Climate Most common compound on Earth

Covers 71% of surface area Land area on Earth = surface on Mars 1.36 billion km3 (326 million mk3)

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 km3 (326 million mk3)

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

Location of WaterLocation 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 Polynesiansand 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 Polynesiansand Chinese in ancient times?

Mosaic of Antarctica from Galileo spacecraft



Location of WaterLocation of Water Oceans 97.22%

Pacific 48% 4280 km (14 kft) deep Atlantic 28% 3930 (13 kft) Indian 20% 3960 (13 kft) Arctic 4% 1205 ( 4 kft)

Oceans 97.22% Pacific 48% 4280 km (14 kft) deep Atlantic 28% 3930 (13 kft) Indian 20% 3960 (13 kft) Arctic 4% 1205 ( 4 kft)

Percentage of freshwaterPercentage of freshwater Percentage of surface

water

Percentage of surface

water

Properties of WaterProperties of Water Present as solid, liquid, gas on Earth

Gas & solid on Mars & most places Solid and liquid (?) on Europa

Polar molecule H2O Oxygen

8 p+, 8 no, 8e-

Hydrogen 1 p+, 1 e-

e- tend to hangaround OxygenMaking that side negative

Present as solid, liquid, gas on Earth Gas & solid on Mars & most places Solid and liquid (?) on Europa

Polar molecule H2O Oxygen

8 p+, 8 no, 8e-

Hydrogen 1 p+, 1 e-

e- tend to hangaround OxygenMaking that side negative

Surface CurrentsSurface Currents Mapped by rubber duckies, bottles Mapped by rubber duckies, bottles

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

poles

Driven by wind, Coriolis, continents Distribute heat from equator toward

poles

Surface Currents: PacificSurface Currents: Pacific

Kuro Siwo warm

current to north

Kuro Siwo warm

current to north

North Pacific Drift brings warm water

eastward

North Pacific Drift brings warm water

eastward

California current

brings cold water south

California current

brings cold water south

Some flow into arctic oceanSome flow into arctic ocean

Oya Siwo: cold

current soutward past Asia

Oya Siwo: cold

current soutward past Asia

East Australian

warm current to

south

East Australian

warm current to

south

West Wind Drift circles AntarctciaWest Wind Drift circles Antarctcia

Cold Peruvian current brings

fish toward shore

Cold Peruvian current brings

fish toward shore

Surface Currents: AtlanticSurface Currents: Atlantic

West Wind Drift

dominates south

Atlantic currents

West Wind Drift

dominates south

Atlantic currents

Gulf Stream feeds North

Atlantic Drift, dominates

north Atlantic currents

Gulf Stream feeds North

Atlantic Drift, dominates

north Atlantic currents

COLD Labrador current drives

subsurface currents

COLD Labrador current drives

subsurface currents

Brazilian & Benguela currents

circle south Atlantic

Brazilian & Benguela currents

circle south Atlantic

COLD Canaries current past

Africa

COLD Canaries current past

Africa

Gyres: Circular CurrentsGyres: Circular Currents

Turning and turning in the widening gyreThe falcon cannot hear the falconer;Things fall apart; the centre cannot hold;

William Butler Yeats, The Second Coming

North Atlantic Gyre

North Atlantic Gyre

GyresGyres 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!Sea Level isn’t level!

Sea LevelSea 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

HighHighLowLow

Residuals = departure from

normal

Residuals = departure from

normal

Click for Quicktime

Movie of Sea surface height

and temperature.

Click for Quicktime

Movie of Sea surface height

and temperature.

P:\aod\SLU\SOAR\EarthClimate\sshsst-globalocean.mov

Regional Surface CurrentsRegional Surface Currents Equatorial Currents

Drive upwelling in east, spreading in west

Equatorial Currents Drive upwelling in east, spreading in west

Currents driven by trade windsCurrents driven by trade winds

Water leaving shore pulls water up from below: upwelling

Water leaving shore pulls water up from below: upwelling

Water deflects N & S due to continents & Coriolis

Water deflects N & S due to continents & Coriolis

Slackened trade winds allow warm water to slosh east,

stopping upwelling of nutrient-rich water

Slackened trade winds allow warm water to slosh east,

stopping upwelling of nutrient-rich water

Regional Current VariationsRegional 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

Normal trade winds push warm surface

water to Asia allowing upwelling of cold,

nutrient-rich, water near South America

Currents & Ocean LifeCurrents & Ocean Life Nutrients

compounds of nitrogen, silicon, phosphorous minerals carried by upwelling cold water

Phytoplankton Fish food (bottom of the food chain) CO2 sink (absorb ½ Earth’s CO2) 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) CO2 sink (absorb ½ Earth’s CO2) Some toxic (algae blooms, “red tides”)

Fish Prefer living in warmer water

Best fishing where cold & warm water meet! eg. The Outer Banks

1997-98 El Niño building

…

1997-98 El Niño building

…

1997-98 El Niño fading …

1997-98 El Niño fading …

ENSOENSO Trigger unknown

Sea Surface Temperature monitored for

signs of building El Niño

Trigger unknownSea Surface Temperature monitored for

signs of building El Niño

Regional Current VariationsRegional 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

Regional Current VariationsRegional 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

C:\Documents and Settings\aod\AOD\SLU\SOAR\climate\sshsst-globalocean.mov

Regional Current VariationsRegional Current Variations Gulf Stream

Keeps Europe warm!! Drives worldwide currents

Gulf Stream Keeps Europe warm!! Drives worldwide currents

Deep Ocean CurrentsDeep 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.Cold, salty water sinks to bottom.

Warm surface water gets colder and saltier than

subsurface water.

Warm surface water gets colder and saltier than

subsurface water.

North Atlantic DownwellingNorth 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

C:\Documents and Settings\aodo\AOD\Courses\Climate\Images\Ocean\NAC.rm.ram

North Atlantic DownwellingNorth 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

Deep Ocean CirculationDeep Ocean Circulation Great Conveyor Belt moving HEAT

circuit takes about 2000 years

Great Conveyor Belt moving HEAT circuit takes about 2000 years

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

Thermohaline

Shutdown?

Thermohaline

Shutdown?13,400 years ago

Lake Iroquois drained through

lake Champlain and Hudson Valley into

Atlantic

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

”

http://www.whoi.edu/

http://www.whoi.edu/media/2004_donnelly_lake_iroquois.html



Thermohaline

Shutdown?

Thermohaline


Lake Candona formed from

remnant of Lake Iroquois

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 ”

http://www.whoi.edu/

Thermohaline

Shutdown?

Thermohaline


Lake Candona increases as glacier continues retreating

13,100 years ago Lake Candona

increases as glacier continues retreating



Period ”

Thermohaline

Shutdown?

Thermohaline


Lake Candona drains through St. Lawrence Valley, seawater intrudes as Champlain Sea

13,000 years ago Lake Candona

drains through St. Lawrence Valley, seawater intrudes as Champlain Sea



Period ”

Thermohaline ShutdownThermohaline 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 Iroquois draining through Hudson Valley: Intra-Alleroid Cold Period

Lake Candona draining through St. Lawrence Valley: Younger Dryas

Lake Candona draining through St. Lawrence Valley: Younger Dryas

Ocean ChangesOcean 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 1022 J

Atmosphere 6.6 x 1021 J

Curry, WHOI, OCCI

The oceans have absorbed about 30 times more heat than

the atmosphere since 1955

Oceans 18.2 x 1022 J

Atmosphere 6.6 x 1021 J

Curry, WHOI, OCCI

Ocean ChangesOcean Changes

Salinity Decreasing

in north Atlantic

Salinity Decreasing

in north Atlantic

cf. Curry, WHOI, OCCI

Ocean ChangesOcean 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... ”

Ocean ChangesOcean 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.”

SOAR 2005 Ocean Circulation and Heat Transport. Coriolis Force: All moving objects are deflected to...

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