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 Research Published 26-July-2007 Presented by Jason English Journal Club 26-September-2007

2. GHG and Trop. Ozone effect on climate

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

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/m 2 Asia aerosol RF: -10 to -50 W/m 2 (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 scenarious 2 separate simulations with present climate use, 5 year integ. avg

7. c SO4 NO3 POA

8. c SOA BC O3

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

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

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

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

14. Change in Atmospheric T 2000 - 2100 Latent heat

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

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

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

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

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

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

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