WISSARD Geophysics

The WISSARD Geophysics Team completes a second successful field season in 2011-2012.

Photo Gallery: 
C-17 unloading. The geophysics crew arriving at McMurdo, the main US base.
Ice Runway:  Ice runway used for landing planes in the early part of the season before the ice melts.  The Royal Society Range is in the background across McMurdo Sound.
Radar Sled:  The insulated radar sled is made entirely of wood to minimize interference and houses the receiving unit and computer electronics.
.  Inside view shows the ruggedized military computer strapped down for a rough ride across the bumpy surface.
Conestogas:  Our lightweight shelters for acquiring seismic profiles are modeled after Conestoga wagons used to cross the American prairies.  These were designed by scientists at Penn State.
SLW in Wind:  Windstorms (ground blizzard) are frequent occurrences on the ice plain.  Winds here are about 25 knots.
Basal Reflectivity:  Map of the bed reflectivity as measured by the radar.  Brighter areas (red colors) show regions of liquid water, blue colors are dry.  The abrupt transition across the lower part of the lake in the figure results from a ridge (see the radar profile) separating wet from dry areas.
SLW Hydropotential:  Hydropotential map of the subglacial lake Whillans region showing how water enters and drains from the lake.  Areas of lower hydropotential (blue colors) fill first, thus the deep depression near the lake center.  Water enters from the low area to the left and likely drains near the top right when a threshold is exceeded.  This map is made using a combination of surface topography obtained from precision GPS and bed topography from the radar.
SLW Geophysics survey:  Map of the subglacial lake Whillans region showing the grid of radar profiles.  Diagonal lines are IceSat laser tracks showing changes in elevation of the lake surface over a two year period.  Largest changes (larger circles) occur near the lake center and coincide with areas of deepest hydropotential in that map.  Seismic profiles were also acquired along a number of the same lines.
SLW Radar Cross Profile:  Radar profile approximately midway across subglacial lake Whillans.  The ice flow direction is into the page.  Abrupt change in radar brightness approximately two-thirds of the way across the profile at the position of the bump shows the boundary between wet and dry conditions coincident with the bump which is actually a ridge running along this side of the lake.