Mendenhall Glacier Science - University of Alaska Southeast

Mendenhall Glacier Science
by Michael Hekkers, July 6, 2010
• Terminus changes & ice velocity
• Mass balance ELA,
accumulation/ablation zones
• Bathymetry
• Herbert & Eagle Glaciers
• Other research and future work
Global warming in Juneau?
• average mean temp (high plus low) 19442007 +0.04°F/yr (+2.5°F)
• winter (Oct –Mar) + 0.059°F/yr (+3.7°F)
• precipitation +0.2”/yr (0.5cm/yr) R2 0.39
Terminus
Changes
• 1760-2009 4.66 km (2.9
miles)
• 2008-2009 59 m/yr (194 ft)
• 2005-2009 52 m/yr
• 2000-2005 58 m/yr*
• 1997-2000 66 m/yr*
Highlights*:
• 366 m/yr summer 2004
• 12 m/yr spring 02- spring
04
• Calving represents 2.6%4% total ice loss
• Extreme Ice Survey
cameras
• UAS meteorological
station and terminus
Camera
SEAMONSTER- sensor web
example: katabatic winds
4-26-2010 12:02PM
http://seamonster.jun.alaska.edu/webcam/MendTerm/00_LATEST_IMAGE.jpg
6-13-10 4AM
6-30-10 10:42AM
Terminus locations
measured at over
10 locations
• Projected
locations based
on 18-25
meters/year
retreat on rock
outcrop
Ice velocity
and depth
• Upper north branch 116
m/yr
• Lower N & S branch 105
m/yr (550 m depth)
• Flux Gate 145-160 m/yr
(600 m depth)
• North Star 96 m/yr (500m
+ depth)
• Terminus 51-93 m/yr
Annual Mass Balance- water
• Geodetic
– Laser Altimetry-small plane
– Photogrammetryoverlapping photos
– Satellite- gravity,
microwave
• Stratigraphic
– Ablation zone
• Steam drill in ablation
wires May
• Measure ablation wires
September
– Accumulation zone
• September, dig pits to 1 yr
old snow, or marked layer,
measure density
• Look for last fall’s magnets
or sawdust layer
• Place more magnets or
visual clues (sawdust,
dye)
Mass
BalanceGeodetic
Courtesy of Chris Larsen, University of Alaska Fairbanks, Geophysical Institute
Mass balance sites
• Equivalent to
32,000 Olympic
swimming pools
lost per year
• Equivalent to
52,000 Olympic
swimming pools
lost per year
Taku Glacier flight lines
• Equivalent to
104,000 Olympic
swimming pools
gained per year
• Equivalent to
64,000 Olympic
swimming pools
lost per year
Mass
BalanceStratigraphic
Near right side waterfall
Bench site ~130 m elev.
Accumulation stakesLower North Branch,
April 2009
ELA – only climatically derived glacier feature
Photo Logan Berner, Hades Highway, Taku Glacier
9/2005
1998-2009 Accumulation (blue)
Ablation (red)
Dr. Cathy Connor’s Mendenhall Lake depth measurement team
Mendenhall Lake Depth
FAQ-How tall is the
terminus?
5-70’ depending on
when and where it’s
measured.
Projects
• Modeling winter
accumulation
– Weather station on divide
– Accumulation stakes
– Compare to current
precipitation and
temperature at airport,
Eaglecrest
• Future accumulation zone
weather station &
lidar/radar station
Projects- future depth sounding
Peter Flynn
Eagle Glacier July 2009
Peter Flynn
Other UAS
Research
• Lemon Creek Glacier
catastrophic lake
draining (Jökulhlaup)
-affects glacier
velocity
-stream hydrology
Gulf of Alaska Glaciers Ancient Nutrient Source
Hood et al, 2009, doi:10.1038/nature08580
The End
Unnamed spire, top of S. Branch of Mendenhall, accumulation site out of view in low
Thanks
• Faculty- Cathy Connor, Matt Heavner,
Eran Hood, Roman Motyka
• Students: Nick Korzen, Ivy Smith, David
Sauer, Nat Kugler, Josh Galbraith, Logan
Berner
• Ron Marvin, Wayne Ward, Laurie Craig
Mendenhall Glacier Facts
http://www.uas.alaska.edu/arts_sciences/n
aturalsciences/envs/links.html