Energy in the Ocean-Atmosphere Climate System

SOEE3410 : Lecture 2Dr Ian Brooks

i.brooks@see.leeds.ac.ukRoom 1.64a Environment Building

http://homepages.see.leeds.ac.uk/~ibrooks

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• The atmosphere-ocean system acts as a heat engine

• Energy OUT = Energy IN

• Work done moving atmosphere and ocean around

Energy IN(solar radiation)

Work doneEnergy OUT

(heat lost to space as infra-red radiation)

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Contributions to global ocean-atmosphere energy budget

Energy Flux (W m-2)

Solar radiation 340

Latent heat 70

Rate of kinetic energy dissipation ~2

Photosynthesis ~0.1

Geothermal heat flux 0.06

World energy production (fossil fuels) 0.02

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Incoming solar radiation342 W m2

Reflected by clouds, aerosol & atmosphere

77

168

30

Reflected by surface

Absorbed by surface

Absorbed by atmosphere

67

thermals

24

24Evapo-transpiration

78

78 390 324

324350

40

4030

Surface radiation Absorbed by surface

reflected solar radiation107 W m2

back radiation

emitted by atmosphere

165

Outgoing longwave radiation235 W m2

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IPCC : http://www.ipcc.ch/present/graphics.htm

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0.9

0.8

0.7

0.3

0.1

0.005

0.002

Heat absorbed by the continents (Beltrami et al. 2002)

Heat required to melt continental glaciers at estimated maximum melting rate (Houghton et al. 2001)

Heat absorbed by the atmosphere during 1955-96 (Levitus et al. 2001)

Heat absorbed by the oceans

Heat required to reduce Antarctic sea-ice extent (de la Mare, 1997)

Heat required to melt mountain glaciers at estimated maximum melting rate (Houghton et al. 2001)

Heat require to melt northern hemisphere sea-ice (Parkinson et al. 1999)

Heat require to melt Arctic perennial sea-ice volume (Rotherock et al. 1999)

14.5

0 2 4 6 8 10 12 14 16 18

Estimate of Earth’s heat balance components (1022 J) for the period 1955-1988(after Levitus et al, 2005, GRL, VOL. 32, L02604, doi:10.1029/2004GL021592)

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Ts

SWi

SWr LWe

SWi = Solar (shortwave) radiation

SWr = shortwave reflected

LWe = Infra red (longwave) emitted radiation

= Ts4

Ts = surface temperature

= Stefan-Boltzman constant (5.67 x 10-8 Watts m-2 K-4 )

At equilibrium… SWi = SWr + LWe

No Atmosphere

In the absence of an atmosphere the surface temperature of earth would be approximately 255K (-18ºC). It’s actual mean temperature is 288K (+15ºC)

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Radiation absorbed from ONE direction, heating gas, is re-emitted in ALL directions

CO2

Some radiation passes through atmosphere

Some radiation absorbed by gas molecules

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Ferrel CellPolar Cell

Idealized model of atmospheric circulation.N.B. actual circulations are not continuous in space or time.

60

30

0

30

6090

90N

et R

adia

tion

Hea

t Tra

nspo

rt

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0°

30°

60°

Polar Front

Mid-latitudeJet Stream

Tropicaljet

Deep convection

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IPCC : http://www.ipcc.ch/present/graphics.htm

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From http://geography.uoregon.edu/envchange/clim_animations/index.html

Animation of monthly net Short-Wave (solar) radiation (W/m2)

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From http://geography.uoregon.edu/envchange/clim_animations/index.html

Animation of monthly net Long-Wave (infra-red) radiation (W/m2)

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From http://geography.uoregon.edu/envchange/clim_animations/index.html

Animation of monthly net radiation (W/m2)

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From http://geography.uoregon.edu/envchange/clim_animations/index.html

Animation of monthly sensible heat flux (W/m2)

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From http://geography.uoregon.edu/envchange/clim_animations/index.html

Animation of monthly latent heat flux (W/m2)

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From http://geography.uoregon.edu/envchange/clim_animations/index.html

Animation of monthly change in heat storage (W/m2)

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From http://geography.uoregon.edu/envchange/clim_animations/index.html

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From http://geography.uoregon.edu/envchange/clim_animations/index.html

Animation of monthly surface temperature (ºC)

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From http://geography.uoregon.edu/envchange/clim_animations/index.html

Animation of monthly sea-level pressure (mb) and surface winds

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Concentrations of 3 well-mixed greenhouse gases

Suphate aerosols deposited in Greenland ice

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• Increases in greenhouse gas concentrations change the radiative balance of the earth by reducing the outgoing longwave radiation.

• The climate system must adjust to a new equilibrium.

• The nature of the change in climate state is complicated by the large number of interacting processes.

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Online Resources

• The animations shown in this lecture have been made available at

http://homepages.see.leeds.ac.uk/~ibrooks/envi3410• The were produced by the Department of Geography at the

University of Oregon. These and some additional animations can be found at : http://geography.uoregon.edu/envchange/clim_animations/index.html