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Atmospheric Circulation Response to Future Arctic Sea Ice Loss

Atmospheric Circulation Response to Future Arctic Sea Ice Loss. Clara Deser, Michael Alexander and Robert Tomas. Future Arctic Sea Ice Loss NCAR Coupled Model Simulation Holland et al. (2006). September Sea Ice Extent. Ice Extent (10 6 km 2 ). Model drop 1.8 million sq km, 2024–2025

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Atmospheric Circulation Response to Future Arctic Sea Ice Loss

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  1. Atmospheric Circulation Response to Future Arctic Sea Ice Loss Clara Deser, Michael Alexander and Robert Tomas

  2. Future Arctic Sea Ice LossNCAR Coupled Model SimulationHolland et al. (2006) September Sea Ice Extent Ice Extent (106 km2) Model drop1.8 million sq km, 2024–2025 Observed drop1.6 million sq km, 2006–2007 NCAR CCSM3 model simulation Observations Figure courtesy of Julienne Stroeve

  3. Future Arctic Sea Ice LossNCAR Coupled Model SimulationHolland et al. (2006) September Sea Ice Extent Ice Extent (106 km2) Model drop1.8 million sq km, 2024–2025 Observed drop1.6 million sq km, 2006–2007 NCAR CCSM3 model simulation Observations 1980-99 2080-99 ~ 2xCO2 Figure courtesy of Julienne Stroeve

  4. CCSM3 Arctic Sea Ice Concentration 1980-99 2080-99 (A1B) September (%) March

  5. ApproachPrescribe sea ice cover for 1980-99 and 2080-99to Community Atmospheric Model Version 3 T85 (1.4° latitude x 1.4° longitude); 26 levels DETAILS • 60 year integrations with repeating seasonal cycle of time-average sea ice concentration and thickness: • 1980-99 (CCSM3 historical) • 2080-99 (CCSM3 A1B) • SSTs fixed at 1980-99 values, and set to -1.8 C where sea ice removed

  6. Sea Ice Change: 2080-99 minus 1980-99 Sea Ice (%) Sea Ice (%) Ice loss Ice gain p_12months_ice_pres_fut.gif

  7. Sea Ice Change: 2080-99 minus 1980-99 Sea Ice (%) Sea Ice (%) Ice loss Ice gain p_12months_ice_pres_fut.gif

  8. Surface Energy Flux Response (Wm-2) Sea Ice Energy Flux Sea Ice Energy Flux p_12months_ice_pres_fut.gif Positive upward

  9. Air Temperature Response (°C) Sea Ice Air T 15-20°C Sea Ice Air T p_12months_ice_pres_fut.gif

  10. Air Temperature Response (°C): Land Only Sea Ice Air T 2-5°C Sea Ice Air T p_12months_ice_pres_fut.gif

  11. Snow Depth Response (cm liquid water equivalent) Air T Snow Air T Snow p_12months_ice_pres_fut.gif

  12. Sea Level Pressure Response (hPa) ci=1hPa Sea Ice SLP shading = 95% significant Sea Ice SLP p_12months_ice_pres_fut.gif

  13. Sea Level Pressure Response (hPa) ci=1hPa Sea Ice SLP shading = significant Sea Ice SLP p_12months_ice_pres_fut.gif

  14. How does the atmospheric circulation response to Arctic sea ice loss compare with the response to doubled CO2 in the fully coupled CCSM3?

  15. Sea Level Pressure Response (hPa) ci=1hPa CAM3 CCSM3 CAM3 CCSM3 p_12months_slp_ccsm3_cam.gif

  16. Sea Level Pressure Response (hPa) ci=1hPa Atm Model Coupled Model Atm Model Coupled Model p_12months_slp_ccsm3_cam.gif

  17. SUMMARYAtmospheric Circulation Response to Future Arctic Sea Ice Loss • Largest sea ice loss in summer-fall (July-Nov), but largest surface energy flux response (which forces the atmosphere) in fall-winter (Oct-Mar) • Thermodynamic response: warming (and moistening) of the boundary layer especially in fall-winter (2-5K over land and 15-20K over the Arctic ocean); increased snow cover over Siberia and northern Alaska • Dynamic response: SLP response largest in fall-winter when it accounts for some of the response to 2xCO2 in the coupled model; negligible in summer

  18. Next StepsAtmospheric Circulation Response to Future Arctic Sea Ice Loss • Allow sea surface temperatures to respond to sea ice loss • Similar experiments with a regional high resolution atmospheric model (Cassano et al.) and an AGCM with a resolved stratosphere • Similar experiments for snow cover (Tomas et al.)

  19. Thank You

  20. Extra Slides

  21. Precipitation Response (mm day-1) Sea Ice Precip & SLP Sea Ice Precip & SLP p_12months_ice_slp_precp.gif

  22. p_12months_z500mb_1000mb.gif

  23. p_12months_ice_cldtot.gif

  24. Sea Ice Concentration (%) 1980-99 2080-99 1980-99 2080-99 p_12months_ice_pres_fut.gif

  25. Summer 2007 Arctic Sea Ice Loss September 2007 sea ice (white area) vs. September long term mean (pink line)

  26. 2080-99 minus 1980-99 Surface Energy Flux (Wm-2) SLP (hPa) Surface Energy Flux (Wm-2) SLP (hPa) Ci = 1hPa; Shading sig p_12months_ice_pres_fut.gif

  27. p_t_profile_contour.gif

  28. Surface Energy Flux Response (Wm-2) Radiative (LW) Turbulent (SH+LH) Radiative (LW) Turbulent (SH+LH) p_12months_ice_pres_fut.gif

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