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GHG and Trop. Ozone effect on climate

"Future climate impacts of direct radiative forcing of anthropogenic aerosols, tropospheric ozone, and long-lived greenhouse gases" Chen, W; Liao, H; Seinfeld, J.H. Journal of Geophysical Research Published 26-July-2007 Presented by Jason English Journal Club 26-September-2007.

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GHG and Trop. Ozone effect on climate

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  1. "Future climate impacts of direct radiative forcing of anthropogenic aerosols, tropospheric ozone, and long-lived greenhouse gases" Chen, W; Liao, H; Seinfeld, J.H. Journal of Geophysical ResearchPublished 26-July-2007Presented by Jason EnglishJournal Club 26-September-2007

  2. GHG and Trop. Ozone effect on climate

  3. Aerosol Effect on climate Climate Effects Indirect effect Direct effect Acid Rain (sulfates) Health Effects Reduced Visibility

  4. Why are sulfate aerosols important?

  5. Cause of Global Circulations • Primary cause - uneven heating of the earth causes thermal wind, ocean-atmosphere coupling, Coriolis • Can aerosols affect regional climate? If they affect global circulation, they might Global aerosol RF: -0.5 W/m2 Asia aerosol RF: -10 to -50 W/m2(includes natural)

  6. Everything increases except sulfate, CFCs A2 scenario: heterog. world, no sustainability, slow technology development - highest year 2100 CO2 and SO2 of all SRES scenarious2 separate simulations with present climate use, 5 year integ. avg

  7. SO4 NO3POA c

  8. SOA BCO3 c

  9. 2000-2100 simulations • Equilibrium climate used • GISS GCM, 4x5 resolution, 9 vertical layers, 1 hr time step • 80 yr integration; 50 yr spinup, 30 yr comparisons • This involves constant emissions and forcing • More pronounced differences than transient climate • Aerosol RF • Internal mixtures • Refractive Indices parameterized from volume-weighted mixing rule • Dry nitrate assumed same refractive index as dry sulfate • Gamma distribution SA-weighted dry r=0.3 um, variance=0.2 • Mie theory applied to calculate extinction, SSA, g from refractive indices and size distribution

  10. Change in RF 2000 - 2100 BC over snow,ice Overall, more energy into the system (TOA), but less directly to the surface

  11. Change in RF 2000 - 2100 Heating through most of the tropopause above the surface

  12. Change in Surface T 2000 - 2100 BC over snow,ice Scat.aerosols Hot hot hot Summer,fewerscat. aer.

  13. Change in Surface T 2000 - 2100 High latitude GHG warmer due to ice-albedo feedbackHemispheric winter = more emissions

  14. Change in Atmospheric T 2000 - 2100 Latent heat

  15. Change in Streamfunction 2000 - 2100 baseline Aerosols weaken hadley cell DJF, strengthen it JJA GHG weakens hadley cell

  16. AER & GHG cause increased evap in tropical lower trop = higher absolute humidityRelative humidity controlled by Clausius Clapyron eqn Absolute humidity relative humidity

  17. AER hadley cell effect causes precip changesGHG cause more heating = stronger convection Excess precip change convective precip change

  18. Sea ice melting TOA SW flux affected by albedo and cloud cover changes TOA LW flux affected by water vapor, clouds (GHG affects these) More clouds TOA SW flux TOA LW flux

  19. AER causes warmer air/cooler surfaceGHG cause warmer air and surface Surface sensible heat Surface SW flux Surface latent heat

  20. Regional WINTER Climate Change 2000 - 2100 Why Asia? -> huge AER forcing

  21. Aerosol composition change causes warming, Ozone causes warming, GHG cause warming….Hot Hot Hot!

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