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

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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
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yes
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surface radiative fluxes
atmosphere
Data SHEBA Atmospheric Surface Fluxes Group
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Cloud phase and long-wave
WINTER-gtSPRING
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Cloud phase and long-wave
SPRING-gtSUMMER
May
June
July
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Cloud LW forcing (CFL) as a function of cloud
properties
Chen, Aires, Francis, Miller, J Climate 2006
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Liquid water path data and models
Gorodetskaya et al, accepted to J Climate
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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
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- Spring large positive trend
Cloud cover over the Arctic Ocean
- Summer no trend
Schweiger, GRL 2004
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April and May have the largest trends in both
Cloud and LW flux
R(LW,CLT)0.6
TOVS
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Changes in Arctic (white bars) annual mean sea
ice extent at the end of the 21st century
Arzel, Fichefet, Goosse, Ocean Modelling 2006
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CCSM3 predicts a large increase in the Arctic
annual mean downwelling LW flux in the 21st
century
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CCSM3 predicts a large increase in the Arctic
annual mean downwelling LW flux in the 21st
century
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WinterSPRING!
increase in cloud liquid water path
increase in LW flux down
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Total downwelling fluxdifference between the
last and first decades of 21st century
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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
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Scale the forcing with the CCSM-predicted changes
in downwelling LW and SW fluxes
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Sea ice thickness change
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conclusions and outlook

• Clouds increase Apr 21, May 12 (1980-2004) gt
  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) -gt surface albedo

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