Ice Analyst Workshop Case Study Routine Monitoring Of Ice Islands WMO IAW-2 Tromso Norway Laurie Weir CIS Vladimir Bessonov AARI June 15-19 2009 Outline • Ice Shelves to Ice Islands • Resources & tools for analysis • Partnerships in tracking • Imagery Review Ice Shelf Genesis • Ice shelves found in the Canadian High arctic are created by very different processes than their Antarctic counterparts. • The Canadian ice shelves are Ward Hunt Ice Shelf created by accumulations of snow and basal accretion on multiyear Ayles Ice Shelf land-fast ice occurring over a long period of time, while the Antarctic Milne Ice Shelf and southern Greenlandic is shelves are created by glacial Petersen Ice systems located on land Shelf extending over the ocean. Serson Ice • This has sometimes led to the Shelf former being termed “ice shelves” and the latter being termed “glacial ice tongues”. (Dowdeswell et al 1994, Jeffries 1987) Wesley Van Wychen CIS CO-OP 2007 Whats going on? • Ice Shelves are Calving as a result of a combination of: – Long-term temperature increases leads to – Long-term reduction in ice shelf thickness; – Dramatic reductions in arctic sea ice leads to more ▪ Open water at the shelf face for extended periods in summer – 2005 & 2008 saw record warm temperatures – High winds (Dr Luke Copland University of Ottawa) Ice Island Calving Mechanisms • With warmer temperatures weakening the ice structure here are some scenarios: • Scenario 1: Persistent winds, tidal action and pressure from the surrounding ice pack may cause cracks to develop within ice shelf: thus producing and ice island. (Holdsworth 1971, Jeffries 1985) Winds Tidal Action Ice Pack Pressure Wesley Van Wychen CIS CO-OP 2007 Ice Island Calving Mechanisms • Scenario 2: Vibrations due to wave action cause a resonance that causes stresses in the ice shelf to the point where a fracture can occur. (Holdsworth & Glynn 1978) Ice Island Ice Shelf Wave Action Causing Resonance Fracture on Ice Shelf Wesley Van Wychen CIS CO-OP 2007 Ice Island Calving Mechanisms • Scenario 3: Strong tides associated with storm surges occur, creating a period of time of intense pressure against the ice shelf, which causes the shelf to crack. The prevailing winds then change, creating open water and areas where the newly calved ice island can flow into. (Sackinger 1987) Storm Surge Wind Wesley Van Wychen CIS CO-OP 2007 Dr. Luke Copland University of Ottawa Fracture History and Tracking • Ayles Ice Shelf –Fractured August 2005 Largest calving event in the last 40+ years • Produced an ice island 66 km sq.—45m thick • 2007 Sept Ayles fractures into 2 ice islands • 2008 Ward Hunt lost 42 km2 • 2008 all of Markham ice island • 2008 Serson lost 60% of its area losing 122 km2 • 2008 July Petermann Ice Island calves - NW Greenland-25 km2 • • 2009 Petersen Ice Shelf has lost ~1/3 its area in last 3 years (Copland) 2009 June Ayles 2nd ice island, now seen in multiple fragments in • McDougall Snd/Penny Strait Ice Shelves to Ice Islands 2005-2009 Modis Shelves Left Remaining Shelves Ward Hunt Milne Petersen-partial Serson 24 May 2009 ©RADARSAT-2 2009 MDA LTD All Rights Reserved Markham Ice Island Ayles Ice Petermann Ice Island islands June 01 2009 RADARSAT-2 Data and Products © MacDONALD, DETTWILER AND ASSOCIATES LTD. (2009) Tracking with Beacons www.sailwx.info 47554-Ayles 47559 & 47560- Serson’s, 47557 Petermann RADARSAT-2 Data and Products © MacDONALD, DETTWILER Petermann Ice Island AND ASSOCIATES LTD. (2009) From Jan 25/09 RADARSAT-2 image: – Size ~15 km2 (down from 21 km2) – Estimated Mass 750,000,000 tons (Assuming a 55m thickness) – Drift speed (Dec-Feb) ~ 9 nm/day Extreme Ice Features May 18 – Ongoing Focus – Ice Islands CANATEC • R2 HH+HV+VV+VH • ALOS PALSAR • In situ obs • Met. data Photos Dr Derek Mueller and Dr Luke Copland Tracking: With High Resolution Imagery Isn’t Always Possible RADARSAT-1 09 MARCH / MARS 2007 RADARSAT-2 14 MARCH / MARS 2009 8M Resolution Need A Multi Sensor Approach … It’s not always black and white ©ESA Envisat ASAR June 06 2009 Landsat 06 June 09 Landsat June 06 and RSAT2-June 07 2256z Landsat 06 June 09 RADARSAT-2 Data and Products © MacDONALD, DETTWILER AND ASSOCIATES LTD. (2009) Calculating Drift of Ayles Fragments RSAT2 June 1 2009 Landsat June 11 2009 June 11 2009 June 15th RADARSAT-2 Data and Products © MacDONALD, DETTWILER AND ASSOCIATES LTD. (2009) Acknowledgements •Workshops such as this illustrate that frequently, we are all monitoring the same ice regime and can improve and learn from each others experience. -------------------------------------------------------------------------------------- RADARSAT-2 Data © MacDonald, Dettwiler and Associates Ltd. (2009) - All Rights Reserved. Données et produits de RADARSAT-2 © MacDonald, Dettwiler and Associates Ltd. (2009) tous droits réservés. •MODIS ©NASA •Envisat images ©ESA • Content- Luke Copland, Derek Mueller, Luc Desjardins, Roger DeAbreu ThanksThanks forfor youryour attentionattention Questions?Questions? .