helen amanda fricker scripps institution of oceanography ted scambos national snow and ice data...
TRANSCRIPT
Helen Amanda FrickerScripps Institution of Oceanography
Ted ScambosNational Snow and Ice Data Center
Bob BindschadlerNASA/GSFC Space Flight Center
Laurie PadmanEarth & Space Research
Photos of Whillans Ice Stream courtesy of Lee Powell and Charlie Bentley, 1987-88 season & edited by Robert Phillips
AAAS/NASA press briefing – San Francisco – 15 February 2007
Antarctic subglacial plumbing Antarctic subglacial plumbing mapped from spacemapped from space
Helen Amanda Fricker
Scripps Institution of Oceanography, La Jolla, CA
AAAS/NASA press briefing – San Francisco – 15 February 2007
NASA’s ICESat mission and launch
Ice Cloud and land Elevation Satellite (ICESat) launched 12 Jan 2003 from Vandenberg, CA
Primary goal of ICESat mission is ice sheet change detection
AAAS/NASA press briefing – San Francisco – 15 February 2007
Schematic of single profile science data measurements, compiled through time to build elevation data sets
ICESat laser altimeter
Surface elevations along a ground track determined from laser time of flight, combined with precise orbit and pointing information
ICESat has 3 lasers and is switched on for ~33 days every ~4 months in a repeat track pattern (which enabled this discovery)
Geoscience Laser Altimeter System (GLAS)
AAAS/NASA press briefing – San Francisco – 15 February 2007
ICESat repeat-track analysis
+ indicates surface uplift (filling)
- indicates surface deflation (draining)
~ indicates oscillating (i.e. doing both)
Conway Ridge
Engelhardt Ridge
Whillans Ice Stream (B)
Mercer Ice Stream (A)
Elevation range 2003-06 (m)
0 9m
MOA (NSIDC)AAAS/NASA press briefing – San Francisco – 15 February 2007
Subglacial Lake Engelhardt
Conway Ridge
Engelhardt Ridge
Largest event in magnitude: deflating
WAIS Meeting 2006
ICESat elevation range (m)
0 9
Whillans Ice Stream (B)
Mercer Ice Stream (A)
AAAS/NASA press briefing – San Francisco – 15 February 2007
Ted Scambos
National Snow and Ice Data Center, Boulder, CO (by telephone)
AAAS/NASA press briefing – San Francisco – 15 February 2007
Conway Ridge
Engelhardt Ridge
Elevation range 2003-06 (m)
0 9m
+ indicates surface uplift (filling)
- indicates surface deflation (draining)
~ indicates oscillating (i.e. doing both)
Satellite image differencing
Uplift
Subsidence
Whillans Ice Stream (B)
Mercer Ice Stream (A)
MOA (NSIDC)AAAS/NASA press briefing – San Francisco – 15 February 2007
Hydraulic potential map
Conway Ridge
Engelhardt Ridge
Conway Ridge
Engelhardt Ridge
Whillans Ice Stream (B)
Mercer Ice Stream (A)
Whillans Ice Stream (B)
Mercer Ice Stream (A)
Elevation range 2003-06 (m)
0 9m
MOA (NSIDC)AAAS/NASA press briefing – San Francisco – 15 February 2007
Hydraulic potential map
Engelhardt Ridge
Conway Ridge
SGL Engelhardt
SGL Conway
SGL Whillans
SGL Mercer
IMPORTANT: This is *not* topography
AAAS/NASA press briefing – San Francisco – 15 February 2007
MODIS difference image: December 2005 minus December 2002
Subglacial Lake Engelhardt
AAAS/NASA press briefing – San Francisco – 15 February 2007
Bob Bindschadler
NASA Goddard Space Flight Center, Greenbelt, MD
AAAS/NASA press briefing – San Francisco – 15 February 2007
Drawdown vs time at 3 crossovers
Subglacial Lake Engelhardt
Total volume loss ~ 2.0 km3
to ocean cavity under Ross Ice Shelf through subglacial channel
AAAS/NASA press briefing – San Francisco – 15 February 2007
Conway Ridge
Engelhardt Ridge
Whillans Ice Stream (B)
Mercer Ice Stream (A)
How much water in the system?
Isolated Subglacial Lake
Engelhardt lost ~2.0 km3 over the
observation period (33 months)
Elevation range 2003-06 (m)
0 9m
-2.0 km3
SgLE
SgLC
SgLM+1.2 km3
+0.12 km3
+0.27 km3SgLW
Remainder of the system had a
net gain ~1.6 km3 over the
same period (~0.6 km3a-1)
Net water gain is likely both
reflecting and influencing the
motion of these major Antarctic
ice sheet outlet streams
AAAS/NASA press briefing – San Francisco – 15 February 2007