Spatial Radiation Imbalance

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Spatial Radiation Imbalance
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Spatial Radiation Imbalance
300 W/m2
EOUT (LW)
EIN (SW)
100 W/m2
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Insolation as a function of latitude

• Why are December and June not symmetric?

Hartmann, 1994
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What does Earth do with this insolation? (back to
current climate)

• albedo as a function of latitude

• what causes this pattern?

Wells, 1997
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Solar insolation as as function of latitude
JunJulAug
Incident insolation
Annual mean
DecJanFeb
Reflected insolation
a x incident insolation
Peixoto and Oort, 1992
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Energy balance as a function of latitude

• Albedo

• Absorbed insolation
• (1-a) x incident insolation

• Emitted terrestrial
• radiation (A B T)

• Net radiation balance
• ( absorbed radn
• - emitted radn)

Peixoto and Oort, 1992
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Net radiation balance at top of atmosphere
Poleward Heat flux
More radiation is absorbed than emitted in the
tropics more radiation is emitted than absorbed
at high latitudes Implies an energy flux from
the equator to the high latitudes
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Net heat flux from tropics Average radiation
imbalance 50 Wm-2 Surface Area of tropics
2p Re2 sin (30o ) Total heat flux from
tropics surface area x imbalance
6.4 x 1015 W 10,000 times global energy
production. 1 Baringer size impact craters
every 11 mins!! 1 Baringer 109 tonnes of
TNT (1 tonne TNT 4.2 x 109 J)
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Poleward heat transport
Total
1 Petawatt 1015W
Atmosphere
Ocean
Trenberth and Caron, 2001
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The atmospheric circulation Satellite observations
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The atmospheric circulation Climate model
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Sea surface temperatures observations
AVHRR
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Observations surface altimetry
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Computer model
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Aside longwave (infrared) emissions to space as
a function of surface temperature
Weve used Stefan Boltman law longwave radiation
?T4
Make our lives easier longwave
radiation A BT
From data
n.b. why not use sT4?