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

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 )

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

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

ELECTROMAGNETIC SPECTRUM

FLUX

FLUX: INVERSE SQUARE LAW

BLACKBODY RADIATION

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

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

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)

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

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

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

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

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

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

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

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 W/(m 2 -K 4 ) T e = 255K = -18°C = 0°F

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

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

Atmospheric Energy Balance

II. Atmospheric Composition and Structure

Vertical Pressure and Temperature Structure Note: logarithmic scale !

Vertical Ozone Structure

Modes of Energy Transfer in the Atmosphere

Physical Causes of the Greenhouse Effect

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

Effects of Clouds on the Atmospheric Radiation Budget: LW radiation

Globally Average Energy Budget

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)

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

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

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

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

Introduction to Climate Modeling: 3-dimensional General Circulation Model (GCM) surface

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

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