1. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI Mechanisms of Upper Ocean Warming in the Arctic and the Effect on Sea Ice Melt Michael Steele, Jinlun Zhang & Wendy Ermold Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle WA Mechanisms of Upper Ocean Warming in the Arctic and the Effect on Sea Ice Melt Michael Steele, Jinlun Zhang & Wendy Ermold Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle WA …through 2007 Steele, Zhang, Ermold (in preparation for JGR)

2. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI 2006 2001 2002 2005 2004 2003 Greenland Alaska Russia sea ice ice from Steele et al., GRL 2008 2000 Ice Retreat & Upper Ocean Warming (relative to 1982-2007 mean) SSTs from monthly mean AVHRR (Reynolds et al) Anomaly of Summer S ea S urface T emperature (  C) 2.5 1.5 0.5 -0.5 -1.5 -2.5 2007 “Pacific Sector” 2008 Summer  July 1 – September 30

3. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI summer SST trends through 2007 : regional anomalies (a) Beaufort-E (c) Bering St (b) Beaufort-W Reynolds et al recent warming in situ satellite WOD’05 smoothed 1930 19651995 summer SST (  C) mean = 2.7°C mean = 0.4°C mean = 5.9°C (f) Kara summer SST (  C) decadal osc? 1930 19651995 mean = 3.1°C (d) Chukchi recent warming recent warming 3.25 std dev 3.05 std dev mean = 2.9°C (e) ESS+ Laptev ice advection influence mean = 2.3°C

4. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI Two Questions: 1.) What causes upper ocean warming in the Pacific sector? 2.) How much sea ice melt is forced by this warm ocean?

5. Michael Steele Polar Science Center / APL University of Washington Dec 18, 2008 SF AGU TED (Thickness & Enthalpy Distribution) sea ice model POP (Parallel Ocean Program) ocean model, v. 1.4 No assimilation in this study Atmos forcing: NCEP 30 vertical levels (5 m resolution in upper 30 m) 22 km resolution (average); 3 grid pts across Bering St. TED (Thickness & Enthalpy Distribution) sea ice model POP (Parallel Ocean Program) ocean model, v. 1.4 No assimilation in this study Atmos forcing: NCEP 30 vertical levels (5 m resolution in upper 30 m) 22 km resolution (average); 3 grid pts across Bering St. Pan-Arctic Ice−Ocean Modeling and Assimilation System (PIOMAS) Jinlun Zhang, Univ. of WA Pan-Arctic Ice−Ocean Modeling and Assimilation System (PIOMAS) Jinlun Zhang, Univ. of WA http://psc.apl.washington.edu/IDAO zhang@apl.washington.edu 45°N Inflow from global model X

6. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI ice Summer Upper Ocean Heat Balance 60 m depth  H/  t  H/  t = F surf + F advec + F o 2000-2006 vs. 2007 2000-2006 2000-2006 vs. 2007 ocean Net air-ocean heat flux Ice-penetrating solar heat flux Ice-ocean heat flux F surf F advec = lateral heat flux convergence June 1  Sept 15 = Pacific sector melt season (Belchansky et al. 2004) Lateral diffusive heat flux Vertical diffusive heat flux Vertical advec/convec heat flux convergence FoFo

7. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI Alaska Russia ice edge 80°N 70°N 180°E N Pole F surf 2007 Summer Ocean Heating 2000-2006 MJ/m 2 0 F advec 2007: Advection near AK is farther East & North, as proposed by Shimada et al., GRL 2006 More extensive More extensive

8. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI Alaska Russia 2007 July Ocean Heating : July 2000-2006 ice edge 80°N 70°N 180°E N Pole early open water → atmospheric warming F surf MJ/m 2 0 F advec

9. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI 20072000-2006 September Ocean Heating : September MJ/m 2 0 Sept: Atmospheric heating  0 2007: Advection near AK is farther East & North, as proposed by Shimada et al., GRL 2006 F advec Alaska Russia F surf ice edge 80°N 70°N 180°E N Pole

10. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI ice Summary: Ocean Heat Balance (2007) 60 m depth ocean Sep’07 F surf J J A ½S½S 0 0.5 ZJ 1.3 ZJ summer 0.25 2000-2006: Much less F surf F Bering St J J A ½S½S summer 0.3 ZJ 0.5 ZJ 0.25 0 0.5 ZJ 0.2 ZJ FoFo summer 0.1 ZJ Summer max: July/Aug (ZJ = 10 21 J)

11. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI Model validation: Ocean Temperature Model validation: Ocean Temperature Under Ice Depth (m) Temperature (°C) -2 -1 0 1 2 0 10 20 30 40 50 60 BGEP CTD data (Proshutinsky et al) ice edge Aug 2005 Model:  0.5°C too cool Open Water Alaska Russia CTD observations (SBI program) 8°C 6 4 2 0 -2 Model bias: +0.3°C std error: 1.8°C Model SST Observed SST T f  -1.8°C

12. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI ice Question #2: Summer Ice Mass Balance warm ocean  h top  h bot h h local warming local warming  h botA =  h botO + ocean dynamics warming ocean dynamics warming Top vs. Bottom Melt Atmos vs. Ocn Dyn Melt = 0 for a quiescent ocean F Otot  h botO =  h bot * ( F AO + F Otot ) F Otot  h botO =  h bot * ( F AO + F Otot ) F AO  h botA =  h bot * ( F AO + F Otot ) F AO  h botA =  h bot * ( F AO + F Otot )

13. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI Sept’07 ice edge  h botO = Ice melt from ocean dynamics July ‘07 0 0.25 0.5 0.75 1.0 1.25 Melt (meters) warm warm SST strong advec Alaska Russia

14. 0 0.25 0.5 0.75 1.0 1.25 Melt (meters) July 2007 Melt Budget  h botA hh  h botO  h top Sept’07 ice edge

15. Michael Steele Polar Science Center / APL University of Washington Dec 18, 2008 SF AGU June July 2000-2006 2007 2000-2006 2007 Ice Volume Melt Budgets in the Pacific sector Ice Volume Loss (  10 3 km 3 ) ½ Sept  vol botO  vol botA  vol top Aug Bering St Inflow Lots of early summer melt in 2007 Lots of early summer melt in 2007 Much less late summer melt in 2007 Much less late summer melt in 2007 …no ice left to melt! Summer Bering St. inflow increases over the summer, but amount of ice melted decreases Sep’07 ice Pacific sector 2007 total only slightly higher (Lindsay et al., J. Climate 2009) 31% 29% 40%

16. Michael Steele Polar Science Center / APL University of Washington Dec 18, 2008 SF AGU total top melt total bottom melt  h top Ice area (10 6 km 2 ) = 2.6 2.5 2.3 2.0  h botO = 0.54 m = 1.28 m 0.45 m 0.40 m 0.18 m 0.28 m 0.04 m ice 0 m 1 2  h botA summer ice melt 0.24 m 0.22 m JuneJulyAug ½ Sept total top melt total bottom melt  h top ocean atmos Ice thickness Budget 0.27 m 0.32 m 0.31 m 0.62 m 0.61 m Ice area (10 6 km 2 ) = 2.6 2.2 1.0 0.7  h botO = 0.64 m = 1.72 m  Perovich et al. GRL ’08 Beaufort Ice Buoy Buoy: 0.65 m  Buoy: 2.10 m  0.17 m 0.05 m ice 0 m 1 2  h botA Sep’07 ice Pacific sector summer ice melt

17. Michael Steele Polar Science Center / APL University of Washington Dec 18, 2008 SF AGU AOMIP: 1) Work with Wieslaw, others to compare the roles of surface heating, Pacific inflow in ocean warming (ask for summary info eg, area-ave #s for budgets) 2) Same for top vs. bottom melt Sep’07 ice Pacific sector Pacific sector Alaska Russia As a result, ice bottom melt rate was 34% faster in 2007, although the total VOLUME of ice melted was ~same. 2000-2006 2007 ice Most (70-80%) ocean warming is caused by local atmospheric heating (except near AK) The upper ocean warmed TWICE AS MUCH in 2007 (relative to 2000-2006). 2000-2006 2007 Answers…

18. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI Bars with Numbers 2.36 1.82 4.66 4.49 1.72 1.28 3.22 3.12

19. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI SST anomalies: Bering St. & Chukchi Sea Bering St SST (  C) Reynolds et al in situ satellite WOD’05 smoothed 1995 3.25 std dev Standard deviation 3.05 std dev Chukchi Woodgate et al. (2006) 1995

20. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI omocn omsurf topmelt JUN JUL AUG SEP SUMMER -0.05 -0.04 -0.10 -0.11 -0.06 -0.12 0 0 -0.21 -0.27 -0.08 -0.05 -0.12 -0.05 -0.12 -0.26 -0.08 -0.10 -0.40 -0.46 -0.17 -0.16 -0.42 -0.49 -0.12 -0.10 0 0 -0.71 -0.75 Greenland Alaska Greenland Alaska Greenland Alaska Greenland Alaska Greenland Alaska Perovich Location Values Numbers are in units of meters.

21. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI The Historical Record SST Reynolds et al in situ satellite  0-10 m  WOD’05 smoothed 2007: 3.05 std dev from Steele et al., GRL 2008 summer SST anomaly (  C) 1995 mean = 2.9°C Chukchi Sea

22. Michael Steele Polar Science Center / APL University of Washington Jan 14, 2009 AOMIP WHOI Alaska Russia 2007 2000-2006 August Ocean Heating : August ice edge 80°N 70°N 180°E N Pole Atmospheric warming: More extensive in 2007 Much larger than F advec overall, ( although near AK, F advec >> F surf ) F advec F surf MJ/m 2 0

23. Michael Steele Polar Science Center / APL University of Washington Dec 18, 2008 SF AGU JuneJulyAug ½ Sept total top melt total bottom melt  h top ocean atmos Ice thickness Budget: 2007 0.27 m 0.32 m 0.31 m 0.62 m 0.61 m Ice area (10 6 km 2 ) = 2.6 2.2 1.0 0.7  h botO = 0.64 m = 1.72 m  Perovich et al. GRL ’08 Beaufort Ice Buoy Buoy: 0.65 m  Buoy: 2.10 m  0.17 m 0.05 m ice 0 m 1 2  h botA Sep’07 ice Pacific sector summer ice melt

24. Michael Steele Polar Science Center / APL University of Washington Dec 18, 2008 SF AGU JuneJulyAug ½ Sept total top melt total bottom melt  h top ocean atmos Ice thickness Budget: 2000-2006 Ice area (10 6 km 2 ) = 2.6 2.5 2.3 2.0  h botO = 0.54 m = 1.28 m 2007: 0.64 m 2007: 1.72 m 0.45 m 0.40 m 0.18 m 0.28 m 0.04 m ice 0 m 1 2  h botA Sep’07 ice Pacific sector summer ice melt 0.24 m 0.22 m