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Some thoughts on sea ice retreat in 2007

IABP 18 annual meeting At CLS on June 16-18 2008. Some thoughts on sea ice retreat in 2007. Takashi Kikuchi (& Jun Inoue) Institute of Observational Research for Global Change Japan Agency for Marine Earth Science and Technology.

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Some thoughts on sea ice retreat in 2007

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  1. IABP 18 annual meeting At CLS on June 16-18 2008 Some thoughts on sea ice retreat in 2007 Takashi Kikuchi (& Jun Inoue) Institute of Observational Research for Global Change Japan Agency for Marine Earth Science and Technology Edge of the Arctic multiyear ice @ 83.2N, 62.0Eon August 14, 2007

  2. Sea Ice drift speed and Ocean-to-ice heat flux Photo during the USCGC Healy Trans-Arctic cruise between Aug.5 and Sept. 30, 2005 Takashi Kikuchi Institute of Observational Research for Global Change/ Japan Agency for Marine-earth Science and Technology (IORGC/JAMSTEC)

  3. Ocean-to-Ice Heat Flux estimation (Kikuchi et al., in preparation) Photo during the USCGC Healy Trans-Arctic cruise between Aug.5 and Sept. 30, 2005 J-CAD 6/2003 Ocean-to-Ice Heat Flux estimated by using ice-drifting buoy data (e.g., McPhee et al., 2003) JAMSTEC Compact Arctic Drifter (J-CAD) ρ: water density, Cp: specific heat of seawater, CH: bulk heat transfer coefficient, u*0: internal friction velocity, δT: temperature above the freezing point κ: von Karman's constant (0.4), V: ice velocity relative to the surface geostrophic flow f: Coriolis parameter, z0: hydrographic roughness of the ice undersurface, A & B; constants for neutral static stability 　　　　(with values 2.12 and 1.91, respectively). POPS / 2006 Polar Ocean Profiling System (POPS)

  4. Ocean-to-Ice Heat Flux estimation (Kikuchi et al., in preparation) Photo during the USCGC Healy Trans-Arctic cruise between Aug.5 and Sept. 30, 2005 7 days moving-averaged Ocean-to-Ice Heat Flux detected by J-CAD & POPS data LR MB AB NGR NB Drifting tracks of JAMSTEC buoys deployed near the North Pole since 2000 Apr. May Jun. July Aug. Sept. Oct. Nov. Dec.

  5. Increasing trend Decreasing trend Interannual variability in ocean-to-ice heat flux prior to NPEO period using 1979-2005 IABP sea ice motion data (upper panel). Ocean-to-Ice Heat Flux estimation Sea ice drift speed in JJ is the most important indicators in determining the annual average ocean-to-ice heat flux. Lower panel: Interannual variability in ocean-to-ice heat flux in the Transpolar Drift region estimated by Krishfield and Perovich [2005]

  6. Perovich et al., 2008GRL. Fig.1 (Lower) Courtesy of E. Hudson and C. Haas Trend of Ocean-to-Ice Heat Flux

  7. Conclusion 1) Using ice-drifting buoy data, we examined ocean-to-ice heat flux (Hf) in the Transpolar Drift since 2000. The yearly averaged Hf was greater in 2000 and 2002 than in 2004-2006. 1.42 W m-2 15cm 2) Sea ice drift speed in June and July is the most important factor in determining total heat input from the atmosphere to beneath sea ice during melting season. 1.39 W m-2 15cm 1.52 W m-2 16cm 3) We suggest that Hf displayed an increasing trend before the early 1990s, but weakly decreasing trend after the mid 1990s until at least the mid-2000s. 1.92 W m-2 21cm 2.89 W m-2 31cm 3.10 W m-2 35cm Apr. May Jun. July Aug. Sept. Oct. Nov. Dec. Edge of the Arctic multiyear ice @ 83.2N, 62.0Eon August 14, 2007

  8. However, ……….

  9. As everyone (might) knows, extent of Arctic summer sea ice in 2007 reached a record minimum. Minimum ice extent in September 1979~2000: 7.0 x 106 km2 2005: 5.3 x 106 km2 2007: 4.1 x 106 km2 Ice concentration of the Arctic Ocean on September 16, 2007. Note that the extent of Arctic summer sea ice in 2007 reached a record minimum. Picture was downloaded from NASA Earth Observatory web site http://earthobservatory.nasa.gov/ September sea ice extent [Updated Inoue and Kikuchi (2007,JMSJ)]

  10. Minimum ice extent in September 1979~2000: 7.0 x 106 km2 2005: 5.3 x 106 km2 2007: 4.1 x 106 km2 Cf. Japan Is. : 0.38 x 106 km2 * Note that ice reduction in 2007 from 2005 ice extent was about 2.8 times as large as the area of Japan Islands. What is the reason of sea ice reduction in 2007? September sea ice extent [Updated Inoue and Kikuchi (2007,JMSJ)]

  11. As everyone (might) knows, extent of Arctic summer sea ice in 2007 reached a record minimum. • Thermodynamical reason • Sea ice formation and melting • Radiation, wind, cloud, snow, ice thickness, ocean heat content • e.g., Shimada et al., 2006 GRL • Catastrophic reduction of Arctic Sea Ice (Warming of the western Arctic Ocean) • Perovich et al., 2008 GRL • Sunlight, water, and ice: Extreme Arctic Sea ice melt during the summer of 2007 • Inoue et al., 2008 JGR • Transmittance of SW radiation through sea ice and melt pond • Dynamical reason • Sea ice motion • Wind and/or ocean current • e.g., Inoue and Kikuchi, 2007 JMSJ • Outflows of summertime Arctic sea ice Ice concentration of the Arctic Ocean on September 16, 2007. Note that the extent of Arctic summer sea ice in 2007 reached a record minimum. Picture was downloaded from NASA Earth Observatory web site http://earthobservatory.nasa.gov/

  12. IPCC model Ice extent In September 2007 4.1 million km2 For reducing uncertainness of the model prediction of the Arctic ice condition….. Schematic of Inoue et al. [2008] Transmittance of SW radiation through sea ice and melt pond Inoue, Kikuchi and Perovich [JGR 2008] Using XCTD and sea ice monitoring data during the Healy trans-Arctic cruise in 2005, we examined a relationship between sea ice condition (concentration, pond fraction) and ocean mixed-layer temperature and quantified transmittance of SW radiation through sea ice and melt pond. (Left) Panorama view of sea ice condition on August 14, 2005 at 78.2N, 153.5W. Inoue et al. [2008]

  13. Outflow of Summertime Arctic Sea Ice Observed by Ice Drifting Buoys and its Linkage with Ice Reduction and Atmospheric Circulation PatternsInoue and Kikuchi [2007, JMSJ] J-CAD 6/2003 In the summer of 2005, our drifting buoy went out from the Arctic Ocean with the fastest speed in the 2000s H Beaufort high and Siberian low pressure systems were dominant in 2005 summer. These systems made strong pressure gradient over the Transpolar Drift region and accelerated sea ice drift toward the Fram Strait. L Color contours: Drifting trajectories for each year (thick line: June-September) Black contour: mean SLP from June to September 2005 Shading: anomalies of sea-ice in September 2005 relative to previous 5-year average POPS / 2006 Edge of the Arctic multiyear ice @ 83.2N, 62.0Eon August 14, 2007

  14. Summer SLP (JJAS) regressed on sea-ice extent in September 2005: SLP gradient had a maximum record !! Similar pattern emerged in summer 2005 Ice Extent of the Arctic Ocean in September Summer SLP gradient over Transpolar Drift Sea ice decrease in the Arctic Ocean 　↓ SLP decreasing trend over the Siberian shelf of the Arctic Ocean 　↓ Produce strong pressure gradient over Transpolar Drift 　↓ Enhance ice export from the Arctic Ocean Summer SLP change regressed on raw Arctic sea-ice extent in Sept. Strong SLP gradient between Canadian Basin & Siberia Edge of the Arctic multiyear ice @ 83.2N, 62.0Eon August 14, 2007

  15. 7 L H L How was 2007 ? Maximum SLP gradient AGAIN !! Ice Extent of the Arctic Ocean in September Summer SLP gradient over Transpolar Drift Sea ice decrease in the Arctic Ocean 　↓ SLP decreasing trend over the Siberian shelf of the Arctic Ocean 　↓ Produce strong pressure gradient over Transpolar Drift 　↓ Enhance ice export from the Arctic Ocean

  16. L H L Strong SLP gradient accelerated Warm air & water advection !!

  17. As everyone (might) knows, extent of Arctic summer sea ice in 2007 reached a record minimum. Outflow of sea ice Warming of the Arctic Ocean Ice concentration of the Arctic Ocean on September 16, 2007. Note that the extent of Arctic summer sea ice in 2007 reached a record minimum. Picture was downloaded from NASA Earth Observatory web site http://earthobservatory.nasa.gov/

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