Elements of the Sun; Solar Radiation

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Chapter 3 Atmospheric Radiative Transfer and
Climate
Kiehl and Trenberth (1997)
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Energy Balance at the TOA (Ch. 2)
Planetary albedo Outgoing longwave radiation
(OLR) Net incoming radiation Movie of net
incoming radiation Zonal mean net radiation at
TOA
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Why do we global wind patterns (general
circulation)?
Unequal heating of tropics and poles
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General Circulation of the Atmosphere
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Radiative Forcing
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The greenhouse effect
Solar radiation
Long-wave radiation
236 Wm-2
236 Wm-2
Equivalent T 255 K (-18ºC)
390 Wm-2 T 288 K (15ºC)
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Nuclear Configuration and Permanent Dipole
Movement
Symmetric, linear molecules (Both ends look the
same)
Nonlinear or bent
Have pure rotation bands
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Vibrational Modes of Diatomic and Triatomic
Molecules
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Nitrous Oxide
Atmospheric Absorption
Methane
Solar radiation passes rather freely through
earth's atmosphere, but earth's re-emitted
longwave energy either fits through a narrow
window or is absorbed by greenhouse gases and
re-radiated toward earth.
Ozone
Absorption (100)
Water Vapor
Carbon Dioxide
UV
IR
Total Atmo
Wavelength
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Spectra of outgoing radiation from Earth observed
by IRIS on Nimbus 3
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Clouds and Radiation

• 1. Cloud maps

2. Radiation plots
Cloud forcing cloudy cloud-free NET SW LW
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Thermal equilibrium profiles
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The Enhanced greenhouse effect

• Solar (S) and longwave (L) radiation in Wm-2 at
  the top of the atmosphere

S L 236 236
S L 236 236
S L 236 236
S L 236 236
T -18C
CO2 x 2 Feedbacks H2O (60) Ice/Albedo
(20) Cloud? Ocean?
CO2 x 2
CO2 x 2
TS 15C
TS 15C
DTS 1.2K
DTS 2.5K
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The climate system
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The Development of Climate models, Past, Present
and Future
Late 1960s
Early 1980s
Mid 1990s
Present day
Late 2000s?
Mid 1950s
Atmosphere
Atmosphere
Atmosphere
Atmosphere
Atmosphere
Atmosphere
Land surface
Land surface
Land surface
Land surface
Land surface
Ocean sea-ice
Ocean sea-ice
Ocean sea-ice
Ocean sea-ice
Sulphate aerosol
Sulphate aerosol
Sulphate aerosol
Non-sulphate aerosol
Non-sulphate aerosol
Carbon cycle
Carbon cycle
Atmospheric chemistry
Sulphur cycle model
Non-sulphate aerosols
Ocean sea-ice model
Off-line model development Strengthening
colours denote improvements in models
Land carbon cycle model
Carbon cycle model
Ocean carbon cycle model
Atmospheric chemistry
Atmospheric chemistry
Modified based on John Houghton
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Coupled atmosphere / ocean climate model
Radiation
Atmosphere Density Motion Water
Heat Exchange of Momentum Water
Ocean Density (inc. Salinity) Motion
Sea Ice
Land
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30km
19 levels in atmosphere
2.5 lat
3.75 long
THE HADLEYCENTRETHIRDCOUPLEDMODEL -HadCM3
1.25
1.25
20 levelsin ocean
-5km
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Physical Feedbacks

• Water vapour
• Ice albedo
• Clouds
• Oceans
• Ice sheets

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Cloud Radiation Feedback
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Cloud radiation feedback
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Global average change in T /C
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Model Estimates of Cloud Radiative Forcing with
CO2 Doubling
Cloud forcing cloudy cloud-free NET SW LW
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Effect of cloud feedback formulation on climate
prediction

• Feedback scheme Global Av
  Temp change,C
  for doubled CO2
• RH 5.3
• CW 2.8
• CWRP 1.9
• after Senior Mitchell, Hadley Centre

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Net cloud forcing January to July

• Hadley Centre