ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Ice Shelf Ocean Interaction in ECCO - IcES Michael Schodlok X. Wang, A. Khazendar, I. Fenty, M. Flexas Sbert, J. Mouginot, E. Rignot, D. Menemenlis  Larsen Ice Shelf  Tides in Pine Island Bay  Icebergs near Thwaites Glacier

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Ice shelf ocean processes: ECCO modeling approach: - Ice shelf rigid, no flexural response, virtual fluxes - northward movement and melting compensate

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Model Results ECCO2 – Circumpolar Model Domain Cold Water Ice Shelves: shielded from warm waters by: - coastal current - slope front  melting well represented (still in equilibrium?) Warm Water Ice Shelves: ‘direct’ access of warm Circumpolar waters into the sub-ice cavity  melting not well represented shape of cavity transient response WAIS Adelie Coast Sabrina Coast Larsen Eastern Weddell

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Cosgrove IS Pine Island IS Crosson IS Dotson IS Abbot IS importance of water column thickness (initial, transient) importance of continental shelf bathymetry warm CDW pathways onto the continental shelf Warm Water Ice Shelf Schodlok et al., 2012

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Temperature in 390 mSalinity in 390 m WDW Larsen C – cold water ice shelf ice shelf separated from water water body resolve slope front onshore flux of Warm Deep Water (WDW) bathymetries from IceBridge, Smith/Sandwell, Rtopo surface forcing JRA, ERA Interim

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Mean Melt Rates 1982 – 2011 JRAERA SandS: 0.92 m/a1.01 m/a Rtopo: 0.84 m/a0.94 m/a IceBr : 0.88 m/a1.00 m/a Larsen B: 0.24 m/a Larsen B/C Melt rates Cold water ice shelves less (?) susceptible to: - water column thickness - bathymetry of continental shelf off shore - surface forcing (10% increase in melt) Larsen B - doubling in mean melt from (sufficient to contribute to disintegration ?)

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Pine Island Bay: Introducing Tides Tides in regional model Control run – no tides Run1 – K1 tide Run2 – 8 tidal constituencies – m2, s2, n2, k2, k1, o1, p1, q1 CATS 2008b – L. Padman Addition of tidal components to u and v velocity Integration for 6 months with hourly OBCS How will tides alter the circulation and melting?

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Wang et al., 2012 Tides in Pine Island Bay Total discrepancy for 8 constituencies: ~ 3 cm off shore ~ 6 cm in sub ice cavities Mean melt: Pine Island26.9 m/a +/- 0.1 m/a Thwaites GL22.3 m/s +/- 0.1 m/a -Tidal effects depend on location of ice shelf wrt to M2 effective critical latitude (R.Robertson pers.com.)

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Melt Rate differences Pine Island Bay Largest effects in Abbot Ice Shelf, north of critical Latitude (tidal frequency = inertial frequency) S

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Sea Ice Production in Pine Island Bay Impact on sea ice formation K1 tide -> less sea ice in polynya area -> domain wide similar sea ice production 8 tidal constituencies -> similar sea ice in polynya area -> more sea ice production over the entire model domain Difference plots

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Bathymetry [m] Pine Island IS Cosgrove IS Thwaites GL Abbot IS Dotson IS Getz IS Vertical section Pine Island Bay largest effects of tidal influnce at (a) ice shelf edge (b) shelf break - (a) not significant for effective melting of Ice shelves in Pine Island Bay - (b) mixing of CDW onto continental shelf ?

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Thwaites Glacier: Acceleration Disintegration (?) Impact of iceberg B22A on: - circulation - melting Thwaites Glacier

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Thwaites Glacier – Accelerating – Disintegrating (?) Modis – Terra & Aqua images B22A stable for ~10 years Slightly rotating around northern tip Summer 2011/12 push to move Ice streams Ice Melange Fast Ice B22A Crosson IS

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Impact of Iceberg on Thwaites Glacier melting Digitized Iceberg/-edge position – Modeled Icebergs Iceshelf edge from Database 2011 Iceshelf edge plus Iceberg in 2002 Iceshelf edge plus Iceberg in 2012 Model Runs: - CNTR Baseline depthB22A - Baseline depth – 200 mB22A s - Baseline depth mB22A d - integration for one year with JRA forcing 1979,2001,2009

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Impact of Iceberg on Thwaites Glacier melting largest impact for run B22A d (+200m) on Pine Island - deep in CDW layer, rapid melting - grounding of berg changes circulation, less warm water allowed in cavity, less melting Thwaites? Increased melting -> acceleration ? Berg regardless of size decreases in Thwaites melting by ~ 1m/a But: Berg melt overestimated (~11m/a)

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Sea Ice Production Mechanism for less melting: More Sea ice production between Thwaites and Crosson Cold water inflow with gyre between Ice shelves Satellite Images suggest Fast Ice until 2012 Fast Ice in MITgcm?

ECCO Meeting Pasadena – Nov 2, 2012 Michael Schodlok Summary Larsen C Ice shelf seems to be insensitive to changes in WCT (?) Larsen B small melt rates – still unknown what the ocean contribution to its disintegration is Tides prescribed as OBCS in the Pine Island Bay model - first results show impact on shelf break area - sea ice production is larger with tides – dependent on parameters ? Iceberg in front of Thwaites Glacier - changes in circulation and melting - sea ice production causes less melting with iceberg