1. Earth Systems Science Chapter 3 I. Global Energy Balance and the Greenhouse Effect: The Physics of the Radiation Balance of the Earth 1.Electromagnetic Radiation: waves, photons 2.Electromagnetic Spectrum 3.Flux 4.Blackbody Radiation 5.Planetary Energy Balance

2. ELECTROMAGNETIC RADIATION: WAVES c = speed of light in a vacuum = 3.0 x 10 8 m/s = wavelength (m) v = frequency (1/s or s -1 )

3. v = c = c/v V /c = 1 ELECTROMAGNETIC RADIATION: WAVES Relationship between v, c, and

4. ELECTROMAGNETIC RADIATION: PHOTONS E = hv = hc/ E = Energy (joules, or j) h = Planck’s constant = 6.63 x 10 -34 j-s v = frequency (1/s or s -1 ) c = speed of light in a vacuum (m/s)  = wavelength (m)

5. ELECTROMAGNETIC SPECTRUM

6. http://www.lbl.gov/MicroWorlds/ALSTool/EMSpec/EMSpec2.html

7. FLUX

8. FLUX: INVERSE SQUARE LAW

9. BLACKBODY RADIATION

10. Planck functionWien’s LawStefan-Boltzman law BLACKBODY RADIATION T = temperature (K)  = Stefan – Boltzman constant

11. BLACKBODY EMISSION RATES: PLANCK FUNCTIONS FOR SUN,EARTH At the Sun’s surface

12. RADIATION BALANCE OF THE EARTH: SOLAR (SHORTWAVE) RADIATION Note: area of circle is used here:  r 2 SWin = area * flux SWin =  r 2 S -  r 2 SA SWin =  r 2 S(1-A)

13. RADIATION BALANCE OF THE EARTH: SOLAR (SHORTWAVE) RADIATION: Why we use the area of a circle Earth

14. RADIATION BALANCE OF THE EARTH: SOLAR (SHORTWAVE) RADIATION: Why we use the area of a circle Earth

15. RADIATION BALANCE OF THE EARTH: SOLAR (SHORTWAVE) RADIATION Net SW = Incoming – Outgoing Net SW =  r 2 S –  r 2 SA Net SW =  r 2 S (1-A) Earth’s Energy SWinSWout

16. RADIATION BALANCE OF THE EARTH: TERRESTRIAL (LONGWAVE) RADIATION Earth Note: area of sphere is used here: 4  r 2 LWout = area * flux LWout = 4  r 2  T e 4

17. RADIATION BALANCE OF THE EARTH: TERRESTRIAL (LONGWAVE) RADIATION Net LW = Incoming – Outgoing Net LW = 0 – 4  r 2  T e 4 Net LW = -4  r 2  T e 4 Earth’s Energy LWout

18. Net LW = -4  r 2  T e 4 T e = effective radiating temperature Earth’s Energy LWout RADIATION BALANCE OF THE EARTH: TERRESTRIAL (LONGWAVE) RADIATION

19. RADIATION BALANCE OF THE EARTH: TOTAL RADIATION Assume dynamic equilibrium: IN = OUT Net SW + Net LW = 0 Net SW =  r 2 S(1-A) Net LW = -4  r 2  T e 4  r 2 S(1-A) – 4  r 2  T e 4 = 0  T e 4 = (S/4) (1-A) T e = [ (S/4  ) (1-A) ] 0.25 Earth’s Energy SWin SWout LWout

20. RADIATION BALANCE OF THE EARTH: TOTAL RADIATION T e = [ (S/4  ) (1-A) ] 0.25 S = 1370 W/m 2 A = 0.3  = 5.67 x 10 -8 W/(m 2 -K 4 ) T e = 255K = -18°C = 0°F

21. RADIATION BALANCE OF THE EARTH: GREENHOUSE EFFECT T e = 255K Ts = 288K  Tg = Ts-Te  Tg = 33K = 33°C = 59°F

22. RADIATION BALANCE OF THE EARTH: GREENHOUSE EFFECT Earth’s Surface Earth’s Atmosphere SWLW You can do the same calculation including an atmosphere

23. Atmospheric Energy Balance

24. II. Atmospheric Composition and Structure

25. Vertical Pressure and Temperature Structure Note: logarithmic scale !

26. Vertical Ozone Structure

27. Modes of Energy Transfer in the Atmosphere

28. Physical Causes of the Greenhouse Effect

31. Effects of Clouds on the Atmospheric Radiation Budget: SW radiation SWA*SW SWA*SW

32. Effects of Clouds on the Atmospheric Radiation Budget: LW radiation

33. Globally Average Energy Budget

34. Introduction to Climate Modeling Many types of climate models exist. We discuss some of the more common types, which have different levels of complexity: Zero-dimensional radiation balance models 1-dimensional radiative-convective models 2-dimensional diffusive models 3-dimensional Atmospheric General Circulation Models (AGCM) 3-D coupled atmosphere – ocean models (AOGCM)

35. T e = [ (S/4  ) (1-A) ] 0.25 Earth’s Energy SWin SWout LWout Introduction to Climate Modeling: zero-dimensional radiation balance model

36. Introduction to Climate Modeling: 1-dimensional radiative-convective model One-Layer Radiation Model

37. Introduction to Climate Modeling: 1-dimensional radiative-convective model 1-D Rad-Conv Model surface S/4(S/4)*A Radiation in each wavelength band Convection, latent fluxes Surface: latent, sensible

38. Introduction to Climate Modeling: 2-dimensional climate model Surface North Pole South Pole

39. http://www.arm.gov/docs/documents/project/er_0441/bkground_5/figure2.html Introduction to Climate Modeling: 3-dimensional General Circulation Model (GCM) surface

40. Introduction to Climate Modeling: 3-D coupled atmosphere – ocean models Atmosphere Ocean

41. Climate Feedbacks Water vapor feedback snow/ice albedo feedback IR flux/temp feedback Cloud feedback ???