South Pole Glaciology with the IceCube telescope Kurt Woschnagg University of California, Berkeley for the IceCube Collaboration Open Science Conference, XXX SCAR St. Petersburg, Russia, July 9, 2008

The IceCube neutrino telescope AMANDA 1450 m 2450 m IceCube 1 km 3 of ice instrumented 40 strings/2400 optical sensors (2008) 80 strings/4800 optical sensors (2011) surface

Neutrino-induced muon generates Cherenkov light sensor is hit → (PMT pulse) Digitized pulse sent to surface Need to know about ice: Optical properties Scattering Absorption Depth dependence Wavelength dependence Dust, ash, bubbles Movement Flow, shear nanosecond timing  

scattered absorbed Measuring Scattering & Absorption photon travel time [ns] Monte Carlo model fits to photon timing  2 minimum

Optical properties: Scattering and Absorption SP ice at 1700 m SP ice at 850 m Absorption Scattering dust peaks correspond to cold periods during last glacial period

digital receiver baffles (nylon brushes) laser The Dust Logger

digital receiver laser The Dust Logger High-resolution log of dust concentration baffles (nylon brushes)

1 km ~90 m Distance from South Pole along 150° W (km) Subglacial lake Radar shows sloping isochrons Bingham et al., JGR 112 (2007) F03S26

( 2008 ) (2006) (2007) (2005) Four seasons of Dust Logs in IceCube 21 and 50 : deployed with string 66 and 52 : retrievable

Dust layer tilt over one kilometer -20 m +50 m Hole 52 minus Hole 50

Also seen in SP ice core (Palais et al. 1987) New SP fallout layer ~6 kyr B.P. South Pole ash layers in dust logs Highly absorbing thin layers give unique signature in bubbly ice. Eight ash layers identified so far. The darkest ones are likely tephra from nearby volcanoes.

South Pole Age vs Depth Volcanic and dust feature tie points matched to EDML core (dated with Dome C core)

melting point Model: No strain heating No horizontal advection South Pole ice temperature profile

melting point South Pole ice temperature profile Model: No strain heating No horizontal advection

Ice surface moves 1 inch/day ice flow model (based on temperature) Measuring SP deep glacial flow “new” string (<1 year)“old” string (>9 years) optical time-of-flight measurements assumed stuck at bedrock

Preliminary South Pole deep ice flow old new Expected shear along flow Found shear across flow /9yr IceCube is installing inclinometers to further investigate ice shear

Clean Does impurity content determine where shear occurs? Gow & Meese (2007) Dirty C-axes Temperature-only model too simplistic? More shear in dirty ice? Smaller grains = Faster fabric development (E. Pettit et al.)