Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Spectra of outgoing radiation from Earth observed by IRIS on Nimbus 3Slide 11Slide 12The Enhanced greenhouse effectThe climate systemThe Development of Climate models, Past, Present and FutureSlide 16Slide 17Slide 18Slide 19Physical FeedbacksCloud Radiation FeedbackCloud radiation feedbackGlobal average change in T /CModel Estimates of Cloud Radiative Forcing with CO2 DoublingEffect of cloud feedback formulation on climate predictionNet cloud forcing: January to JulyChapter 3 Atmospheric Radiative Transfer and ClimateChapter 3 Atmospheric Radiative Transfer and ClimateKiehl and Trenberth (1997)Kiehl and Trenberth (1997)Energy Balance at the TOA (Ch. 2)Energy Balance at the TOA (Ch. 2)Planetary albedoOutgoing longwave radiation (OLR)Net incoming radiation Movie of net incoming radiation Zonal mean net radiation at TOAWhy do we global wind patterns (general circulation)?Why do we global wind patterns (general circulation)?Unequal heating of tropics and polesUnequal heating of tropics and polesGeneral Circulation of the AtmosphereGeneral Circulation of the AtmosphereRadiative ForcingRadiative ForcingThe greenhouse effectLong-waveradiation236 Wm-2Equivalent T = 255 K (-18ºC)390 Wm-2T = 288 K (+15ºC)236 Wm-2Solar radiationNuclear Configuration and Permanent Dipole Nuclear Configuration and Permanent Dipole MovementMovementSymmetric, Symmetric, linear molecules linear molecules (Both ends look (Both ends look the same)the same)Nonlinear or Nonlinear or bentbentHave pure Have pure rotation bandsrotation bandsVibrational Modes of Diatomic and Triatomic Vibrational Modes of Diatomic and Triatomic MoleculesMoleculesAtmospheric AbsorptionAtmospheric AbsorptionSolar radiation Solar radiation passes rather freely passes rather freely through earth's through earth's atmosphere, but atmosphere, but earth's re-emitted earth's re-emitted longwave energy longwave energy either fits through a either fits through a narrow window or is narrow window or is absorbed by absorbed by greenhouse gases greenhouse gases and re-radiated and re-radiated toward earth.toward earth.WavelengthAbsorption (100%)Nitrous OxideMethaneOzoneWater VaporCarbon DioxideTotal AtmoIRUVSpectra of outgoing radiation from Earth observed by IRIS on Nimbus 3Clouds and RadiationCloud forcing = cloudy – cloud-freeCloud forcing = cloudy – cloud-freeNET = SW + LWNET = SW + LW2. Radiation plots2. Radiation plots1. Cloud maps1. Cloud mapsThermal equilibrium profilesThe Enhanced greenhouse effectSolar (S) and longwave (L) radiation in Wm-2 at the top of the atmosphereS L236 236T = 18°CS L236 236CO2 x 2S L236 236CO2 x 2S L236 236CO2 x 2+ FeedbacksH2O (+60%) Ice/Albedo (+20%)Cloud?Ocean?TS = 15°C TS = 15°C TS ~ 1.2K TS ~ 2.5KThe climate systemThe Development of Climate models, Past, Present and FutureAtmosphere Atmosphere Atmosphere Atmosphere Atmosphere AtmosphereLand surfaceLand surfaceLand surfaceLand surfaceLand surfaceOcean & sea-ice Ocean & sea-ice Ocean & sea-ice Ocean & sea-iceSulphateaerosolSulphateaerosolSulphateaerosolNon-sulphateaerosolNon-sulphateaerosolCarbon cycle Carbon cycleAtmosphericchemistryOcean & sea-icemodelSulphurcycle modelNon-sulphateaerosolsCarboncycle modelLand carboncycle modelOcean carboncycle modelAtmosphericchemistryAtmosphericchemistryOff-linemodeldevelopmentStrengthening coloursdenote improvementsin modelsMid 1950sLate 1960s Early 1980s Mid 1990s Present day Late 2000s?Modified based on John HoughtonCoupled atmosphere / ocean climate modelRadiationAtmosphere: DensityMotionWaterHeatExchange of: MomentumWaterOcean: Density (inc. Salinity)MotionSeaIceLand19 levels in atmosphere20 levelsin ocean2.5lat3.75 long1.251.25THE HADLEYCENTRETHIRDCOUPLEDMODEL -HadCM330km-5kmPhysical Feedbacks•Water vapour•Ice albedo•Clouds•Oceans•Ice sheetsCloud Radiation FeedbackCloud radiation feedbackGlobal average change in T /CGreenhouse Gases Clouds Change in TNone As Now -32As Now None 4As Now +3% high 0.3As Now +3% low -1X2 CO2X2 CO2As Now+ feedbacks1.22.5Model Estimates of Cloud Radiative Forcing with CO2 DoublingCloud forcing = cloudy – cloud-freeCloud forcing = cloudy – cloud-freeNET = SW + LWNET = SW + LWEffect 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 CentreNet cloud forcing: January to JulyHadley
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