Observations of sea ice and ice sheet interaction in Greenland and the Antarctic Peninsula

Transcription

1 Observations of sea ice and ice sheet interaction in Greenland and the Antarctic Peninsula Twila Moon 1,2, Ted Scambos 1, Mark Fahnestock 3, Ian Joughin 2, Ben Smith 2, Terry Haran 1, Marin Klinger 1, Michiel van den Broeke 4, Willem Jan van de Berg 4, Brice Noël 4 1 National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Science, University of Colorado, Boulder 2 Polar Science Center, Applied Physics Lab, University of Washington 3 Geophysical Institute, University of Alaska, Fairbanks 4 Institute for Marine and Atmospheric Research, Utrecht University

2 Potential link among ice mélange, terminus, & velocity Rigid mélange [Joughin et al., 2008] Jakobshavn Isbræ [NASA Earth Observatory]

3 Potential link among ice mélange, terminus, & velocity Rigid mélange [Joughin et al., 2008] Terminus advance Jakobshavn Isbræ [NASA Earth Observatory]

4 Potential link among ice mélange, terminus, & velocity Rigid mélange [Joughin et al., 2008] Jakobshavn Isbræ Velocity slowing [NASA Earth Observatory]

5 Potential link among ice mélange, terminus, & velocity - Force balance: sea ice may suppress calving with little force [Amundson et al., 2010] Jakobshavn Isbræ [NASA Earth Observatory]

6 Potential link among ice mélange, terminus, & velocity - Force balance: sea ice may suppress calving with little force [Amundson et al., 2010] Narrow, extended fjord Jakobshavn Isbræ [NASA Earth Observatory]

7 GF Northwest Greenland case study GF GF ^_ U ") XY ")XY N XY Velocity scale (m/yr) ice sheet W ") XYXY ") XY ") ") ") ") ") ") ^_^_ ") ^_!A!A J XY ^_ A! ^_ ") XY E XY!A ^_A!A! A A!A!!!A I!A H ^_! A! A SE K!A!AXYXY XY!A! A! A XY XY XY!A ") ^_ A!A! ^_! A! A^_! A! A! AXY +60% +40% +20% % <15% % -20% -40% -60% ice shelf-terminating land-terminating avg vel < 200 m/yr erratic (SOM) E XY XY ocean Open ocean Sea ice fraction 50% Rigid sea ice

8 Sea ice conditions influence seasonal terminus position = 100 m Retreat Advance Open ocean periods: 73% coincide with retreat >50 m [Moon et al., in prep, 2014]

9 Sea ice conditions influence seasonal terminus position = 100 m Retreat Advance Open ocean periods: 73% coincide with retreat >50 m Rigid mélange periods: 56% coincide with advance >50 m [Moon et al., in prep, 2014]

10 Longer sea ice free periods produce sustained retreat Average annual behavior rigid mélange spring/summer retreat glacier bed fall/winter advance glacier bed

11 Sea Ice Fraction Longer sea ice free periods produce sustained retreat Average annual behavior rigid mélange spring/summer retreat glacier bed fall/winter advance glacier bed North = black South = blue

12 Sea Ice Fraction Longer sea ice free periods produce sustained retreat Average annual behavior rigid mélange spring/summer retreat glacier bed fall/winter advance glacier bed North = black South = blue Longer sea ice free periods larger retreat little/no advance

13 Mean velocity (m/yr) - Interpolated (monthly) Longer sea ice free periods produce sustained retreat Longer sea ice free periods Mean terminus position (m) - Interpolated (weekly) larger retreat little/no advance

14 Sea Ice Fraction Surface meltwater is a complicating factor in Greenland Meltwater Runoff (kg/m 2 per day) from RACMO [Moon et al., in prep, 2014] - Seasonal development of surface meltwater runoff coincides with loss of sea ice

15 Sea Ice Fraction Surface meltwater is a complicating factor in Greenland Meltwater Runoff (kg/m 2 per day) from RACMO [Moon et al., in prep, 2014] - Seasonal development of surface meltwater runoff coincides with loss of sea ice - Seasonal velocity changes for most northwestern Greenland glaciers appears more responsive to runoff than terminus change [Moon et al., in review, 2014]

16 Changes in fast ice for Larsen B

17 Sustained and variable fast ice conditions 19-Feb Feb Mar Jan Feb Sep-2014

18 Sustained and variable fast ice conditions 19-Feb Feb Mar Jan Feb Sep-2014

19 Sustained and variable fast ice conditions 19-Feb Feb Mar Jan Feb Sep-2014

20 Examining long-term velocity changes for Crane - PyCorr for featuretracking velocity output from Landsat7 and Landsat8

21 Examining long-term velocity changes for Crane - PyCorr for featuretracking velocity output from Landsat7 and Landsat8 - Able to look at glacier and sea ice/mélange velocities - Interested in long-term (weeks to years) changes in glacier velocity signal

22 Examining long-term velocity changes for Hektoria

23 Greenland sea ice/mélange, terminus, and velocity - Ice mélange corresponds to terminus position - Sustained retreat may be associated with longer sea ice free periods and induce multi-year speedup - Runoff is a complicating factor and seasonal velocity appears more responsive to surface meltwater

24 Greenland sea ice/mélange, terminus, and velocity - Ice mélange corresponds to terminus position - Sustained retreat may be associated with longer sea ice free periods and induce multi-year speedup - Runoff is a complicating factor and seasonal velocity appears more responsive to surface meltwater Antarctic Peninsula sea ice/mélange and glacier interaction - Since loss of Larsen B Ice Shelf, multi-year fast ice has developed at multiple periods near Crane, Hektoria, and Green Glaciers - Periods of open water conditions have also persisted through several months - The region may provide a more simple case study for understanding the interaction of sea ice and glacier dynamics - Techniques for measuring surface velocity continue to improve: we use PyCorr with Landsat7 and Landsat8

25 Thank you