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Recent trends and variability in Canadian Arctic sea ice

Recent trends and variability in Canadian Arctic sea ice. Stephen Howell Climate Research Division January 19, 2010. Thanks to: Adrienne Tivy (IARC), Thorsten Markus (NASA); Steve McCourt (CIS); Bea Alt (CIS); Trudy Wohlleben (CIS); Claude Duguay (UW). Canadian Arctic Sea Ice Domain.

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Recent trends and variability in Canadian Arctic sea ice

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  1. Recent trends and variability in Canadian Arctic sea ice Stephen Howell Climate Research Division January 19, 2010 Thanks to: Adrienne Tivy (IARC), Thorsten Markus (NASA); Steve McCourt (CIS); Bea Alt (CIS); Trudy Wohlleben (CIS); Claude Duguay (UW)

  2. Canadian Arctic Sea Ice Domain

  3. Canadian Arctic sea ice decreases will lag the Arctic Ocean • How is Canadian Arctic sea ice responding to change? September 10, 2041-2060 mean Holland et al., 2006-GRL(left); Sou and Flato 2009-JClim(right)

  4. Recent trends and variability: total and multi-year sea ice • Total sea ice area -8.7% decade-1 (sig) • MYI area -6.4% decade-1 (not sig) Summer Average, 1968-2008 CAA September Average, 1979-2008 Howell et al. 2009-GRL;Tivy et al. submitted-JGR

  5. Recent trends and variability: sea ice phenology parameters • Melt onset -3.1 days decade -1 earlier (sig) • Freeze onset 3.9 days decade-1 later (sig) • Melt season length increasing at 7.0 days decade-1 (sig) • Hudson Bay melt season length increases by 10+ days decade-1 CAA, 1979-2008 • What is driving these changes? Howell et al. 2009-GRL

  6. Sea ice variability: links to surface air temperature SAT and Sea Ice, 1968-2008 NCEP SAT 1968-2008 (oC decade-1) > 0.2oC decade-1 than pan-Arctic Tivy et al. submitted-JGR

  7. Atmospheric circulation links: Atlantic Multi-decadal Oscillation (AMO) in Hudson Bay -20% per decade in July Tivy et al. submitted-JClim

  8. Atmospheric circulation links: Arctic Oscillation & ENSO • Preceding NDJFM ENSO Index • 5 month lead MYI Dynamic & Thermodynamic Interplay Composite MJJAS SAT for El Niño Events Tivy et al. submitted-JGR

  9. Changes in the source input of CAA MYI • Pre-1994; cooler temperatures (shorter melt season)  less dynamic movement but situation is reversed post-1994 • When one source is shut-down the other takes over • Will result in slower decreases within the CAA • CAA MYI for 2007 & 2008 is mostly dynamic import Howell et al. 2009-GRL

  10. Late season sea ice consolidation (landfast) changes 2004-2007: consolidation of the ice in the CAA was ~normal 2008: consolidation of the ice in parts of the CAA was 6-8 weeks late 2009: process of normal consolidation of the ice in the CAA significantly interrupted by strong winds and warm temperatures Dec 2004 Dec 2005 Dec 2006 Dec 2007 Dec 2008 Dec 2009 Courtesy T. Wohlleben (CIS)

  11. Late season sea ice consolidation: 2009 Dual-pol false-colour image: Blue= young ice RADARSAT-22 Nov 2009 HH/HV Courtesy T. Wohlleben (CIS)

  12. Late season sea ice consolidation: 2009 Fractured Multi-year pack ice with young and first year ice in the leads Young ice RADARSAT-2, HHHV, 06 Dec 2009, 1430Z Fast ice Young ice Young ice Mobile, fractured multi-year ice Young ice Borden Island Ellef Ringnes Island Fast ice Fast ice Fast ice Courtesy T. Wohlleben (CIS)

  13. Extreme minima in 1998 and 2007 Howell et al. in prep-JGR

  14. Long term variability: extending the time series back to 1960 Tivy et al. submitted-JGR

  15. Variability in the CAA is difficult to capture Zhang –APL; Howell and Duguay – UW; CIS

  16. Summary • The Canadian Arctic is experiencing sea ice decreases but change varies regionally: • Greatest in for Hudson Bay (~-9% per decade annually; -20 % per decade in July) • Baffin Bay (~-8.9 % per decade annually) • Beaufort Sea (~-5.2 % per decade annually) • CAA (-3% per decade annually; ~-8% per decade in September; No significant trends in MYI) • Seasonal FYI decreases are explained mostly by summertime increases in SAT • ENSO teleconnection increases MYI in the CAA • AMO teleconnection maybe responsible for July Hudson Bay decreases • The source of CAA’s MYI has changed • Less first-year ice survival but more dynamic MYI import attributed to an increase in the length of the melt season (~7 days per decade) • As the transition to a summer-time sea ice free Arctic continues the supply of MYI from the Arctic Ocean to the CAA is unlikely to stop. • Atmospheric circulation continues to force sea ice up against the CAA hence creating very thick ice (15+ m ) that will likely be able to survive 2oC temperature warming

  17. Anomalies continuing in 2010 Re-fracture Courtesy T. Wohlleben (CIS)

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