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Can Arctic Sea Ice Summer Melt be Accelerated by Changes in Spring Cloud Properties?

Can Arctic Sea Ice Summer Melt be Accelerated by Changes in Spring Cloud Properties?. I. Gorodetskaya 1 , B. Tremblay 1,2 , B. Liepert 1 , M. Cane 1. 1 Lamont-Doherty Earth Observatory, New York. 2 McGill University, Montreal. yes. surface radiative fluxes. atmosphere.

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Can Arctic Sea Ice Summer Melt be Accelerated by Changes in Spring Cloud Properties?

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  1. Can Arctic Sea Ice Summer Melt be Accelerated by Changes in Spring Cloud Properties? I. Gorodetskaya1, B. Tremblay1,2, B. Liepert1, M. Cane1 1Lamont-Doherty Earth Observatory, New York 2McGill University, Montreal

  2. yes

  3. surface radiative fluxes atmosphere Data: SHEBA Atmospheric Surface Fluxes Group

  4. February March April Cloud phase and long-wave: WINTER->SPRING

  5. Cloud phase and long-wave: SPRING->SUMMER May June July

  6. Cloud LW forcing (CFL) as a function of cloud properties Chen, Aires, Francis, Miller, J Climate 2006

  7. Liquid water path: data and models Gorodetskaya et al, accepted to J Climate

  8. Total variance in the perennial ice edge attributable to anomalies in forcing parameters, 1980-2004 J. A. Francis and E Hunter also see: Francis, Hunter, Key, Wang, JRL 2005

  9. Cloud cover over the Arctic Ocean: - Spring: large positive trend - Summer: no trend … Schweiger, GRL 2004

  10. April and May have the largest trends in both Cloud % and LW flux R(LW,CLT)=0.6 TOVS

  11. Changes in Arctic (white bars) annual mean sea ice extent at the end of the 21st century Arzel, Fichefet, Goosse, Ocean Modelling 2006

  12. CCSM3: predicts a large increase in the Arctic annual mean downwelling LW flux in the 21st century

  13. CCSM3: predicts a large increase in the Arctic annual mean downwelling LW flux in the 21st century

  14. Winter&SPRING! increase in cloud liquid water path: increase in LW flux down:

  15. Total downwelling fluxdifference between the last and first decades of 21st century

  16. 0-layer thermodynamics model: sea ice thickness and concentration evolution Ta - from NP drifting stations (Lindsay, J Climate 1998) LW, SW LW, SW, Fsens, Flat Fsens(Ta-Ti), Flat Ti Fc ice: A,h Tb=-1.8

  17. Scale the forcing with the CCSM-predicted changes in downwelling LW and SW fluxes

  18. Sea ice thickness change:

  19. conclusions and outlook • Clouds increase: Apr 21%, May 12% (1980-2004) => Arctic Ocean gains ~15 W/m2 more LW radiation (TOVS data) • NCAR CCSM3: • Arctic - more liquid clouds in 2xCO2 world • spring cloud LW warming overwhelms SW cooling • with the above cloud response alone (LW forcing strongest in winter and spring), a 1D ice model reduces an equilibrium sea ice thickness from 4.5 to 2.5 m • positive feedbacks not included! e.g., snow(T) -> surface albedo

  20. Photo from Peter Minnett Arctic Sea Ice Summer Melt can be accelerated by an increase inSpring cloud liquid water path... Big Thanks: Yonghua Chen, Jennifer Francis, Kirstie Stramler, Martin Vancoppenolle, Richard Cullather

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