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Dr. Piotr J. Flatau pcirrus@gmail

SIO209 Cloud Climate Feedbacks. Scripps Institution of Oceanography University of California. Dr. Piotr J. Flatau pcirrus@gmail.com. SIO209 Clouds. SIO209 Clouds. SIO209 Clouds. SIO209 Cloud Climate Feedbacks. Radiative Convective Equilibrium Feedbacks Cloud Physics Feedbacks

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Dr. Piotr J. Flatau pcirrus@gmail

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  1. SIO209 Cloud Climate Feedbacks Scripps Institution of Oceanography University of California Dr. Piotr J. Flatau pcirrus@gmail.com

  2. SIO209 Clouds

  3. SIO209 Clouds

  4. SIO209 Clouds

  5. SIO209 Cloud Climate Feedbacks • Radiative Convective Equilibrium Feedbacks • Cloud Physics Feedbacks • Cloud Formation Feedbacks

  6. SIO209 Cloud Climate Feedbacks • Radiative Convective Equilibrium Feedbacks • Cloud Physics Feedbacks • Cloud Formation Feedbacks

  7. SIO209 Radiative Convective Equilibrium - Examples Clear sky energy balance (IR cooling) Mid morning max. precipitation in tropics Observed temperature differences between fall and spring Stratocumulus balance (subsidence, heat flux, IR cooling) Convection control of SST in the tropics Lapse rate stabilization or destabilization

  8. SIO209 Radiative Convective Equilibrium – IR cooling -100 W/m2 IR cooling RCE (“W. M. Gray”)

  9. SIO209 Radiative Convective Equilibrium - Definition To first order, the atmosphere exists in a state of quasi balance between radiative cooling and the convective processes that give rise to latent and sensible heating.

  10. SIO209 Radiative Convective Equilibrium - 1K/day Radiative cooling - clear sky dT/dt = - F/(cp rho Dz) =-100/(1004 *1.2* 8000) [K/s]= -100/(1000 * 8000) *(60*24*60)= 36*24 10^4/ 8*10^6=36*24/(800)=36*4/100 =about= 1.0K/day

  11. SIO209 RCE - Up Moist Down Dry Evaporation Q=mL= 1g * 2.5 * 10^3J/g F=2.5* 10^3/(24*60*60)= 1/36 W/cm2=1000/3.6 W/m2=250W/m2 L=2.5*10^6 J/kg 1W=1J/s 0.3cm evaporation per day to offsets 100W/m2 of IR cooling

  12. SIO209 RCE Example: Precipitation in Tropics

  13. SIO209 Early Morning Precip Max in Tropics - RCE

  14. Implications for deep convection Mapes, 2002 Hartmann & Larson, 2002

  15. SIO209 Stratocumulus RCE

  16. SIO209 Lilly’s Model of Sc. RCE d T /dt = - (Fnet,base-Fnet,top)/ (cp rho dz) Fnet,top=75W/m2 Fnet,base=15W/m2 Cp=1004 J kg^-1 K^-1 Rho=1.2 kg m^-3 Dz=1km dT/dt=-4 K/day (IR) Subsidence (30mb/d-100W/m2) Heat flux

  17. SIO209 Radiative Convective Equilibrium – SST Control

  18. SIO209 Radiative Convective Equilibrium – SST Control

  19. SIO209 Radiative Convective Equilibrium – Thermostat

  20. SIO209 Radiative Convective Equilibrium Adjustment

  21. SIO209 Radiative Convective Equilibrium – Summary

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