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Arctic clouds, circulation, and sea ice during 2007 and beyond

Arctic clouds, circulation, and sea ice during 2007 and beyond. Jennifer Kay 1,2 , Andrew Gettelman 1 , Kevin Reader 1 , and Tristan L’Ecuyer 2 1 National Center for Atmospheric Research (NCAR) 1 Colorado State University (CSU). MODIS Image from March 10, 2008 (sea ice maximum extent).

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Arctic clouds, circulation, and sea ice during 2007 and beyond

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  1. Arctic clouds, circulation, and sea ice during 2007 and beyond Jennifer Kay1,2, Andrew Gettelman1, Kevin Reader1, and Tristan L’Ecuyer2 1National Center for Atmospheric Research (NCAR) 1Colorado State University (CSU) MODIS Image from March 10, 2008 (sea ice maximum extent)

  2. Lessons and questions from 2007 Data assimilation project (CAM-DART) Early observations for 2008 MODIS Image from March 26, 2008

  3. “A perfect storm” for ice loss in 2007

  4. Cloud and radiative flux differences(2007-2006) Radiative fluxes from 2B-FLXHR produced by Tristan L’Ecuyer (CSU).

  5. Were the 2007 clouds really anomalous?

  6. In a warmer world with thinner ice, natural summertime circulation and cloud variability is an increasingly important control on sea ice extent.Kay, L’Ecuyer, Gettelman, Stephens, and O’Dell(Geophysical Research Letters, 2008)

  7. For clouds, timing is key.

  8. Atmospheric forcing on sea ice loss

  9. Many remaining questions thermodynamic vs. dynamic loss processes cloud-ice-circulation feedbacks 3) year-to-year variability vs. long-term ice thinning 4) models: reliability?, what can they teach us? 5) tipping point? 2008?

  10. Lessons and questions from 2007 Data assimilation project (CAM-DART) Early observations for 2008 MODIS Image from April 13, 2008

  11. Why DART?DART = Data Assimilation Research Testbed Fig. 1 from Rodwell and Palmer (2007) • Science Questions • Do climate models capture observed changes in the atmospheric forcing on sea ice loss? • How does the Arctic ocean surface affect the Arctic atmosphere?

  12. CAM-DART vs. NCEP

  13. DART-CAM Assimilations • Science Questions For Today • How well do CAM/DART reanalyses capture observed changes? (July06 vs. July07) • Does the surface affect the best guess of the atmospheric state? (July07sst vs. July07clim)

  14. CAM-DART July06 vs. July07

  15. July07 CAM-DART obs vs. climo

  16. July07 vs. Sept07 sea ice extent Source: NSIDC

  17. Lessons and questions from 2007 Data assimilation project (CAM-DART) Early observations for 2008 MODIS Image from May 19, 2008

  18. NCEP During 08 Ice Melt

  19. Clouds During 08 Ice Melt

  20. Summary • In a warmer world with thinner ice, the minimum sea ice extent is increasingly sensitive to year-to-year variability in weather and cloud patterns. • The timing of ice loss matters. • CAM-DART can qualitatively reproduce observed changes in the atmospheric forcing on sea ice. • 2008 atmospheric circulation and cloud anomalies are small. But… If the current anti-cyclonic pattern persists/strengthens, there will be significant sea ice loss in 2008.

  21. EXTRA SLIDES

  22. NCEP During 08 Ice Growth

  23. Clouds During 08 Ice Growth

  24. Early Fall Cloud Increases (‘07-’06) Near The Dateline

  25. 2007 Arctic sea ice extent Credit: NSIDC The sea ice extent at the 2007 minimum was 4.13 million km2 down 43% from 1979 and down 26% from the last record minimum in 2005.

  26. Sea Ice Extent: July vs. Sept, 06 vs. 07

  27. DART-CAM noise slide PSL map fc_time=0,3,6 hours

  28. Fall/Winter Clouds/LW Rad at ARM Barrow

  29. Western Pacific Arctic

  30. Western Pacific Arctic Data

  31. 2007 Western Arctic cloud reductions CloudSat/CALIOP data revealed reduced cloudiness and enhanced downwelling shortwave radiation (+32 Wm-2).

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