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Late breaking news from field studies of the Ross Ice Shelf
Douglas R. MacAyeal , Olga Sergienko, Kelly Brunt ,
Marianne Okal, Jonathan Tom, Ronald Ross,
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Objective of study
Iceberg calving
Rift propagation
Unplanned opportunities: GPS12 months of Garmin 3 days of Geodetic
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Background
Rift propagation (Joughin and MacAyeal, 2005)
Tidal motion of WAIS Ice Streams (Bindschadler et al, 2003)
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Estimated velocity for C19
Joughin and MacAyeal (2005)
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Ice flow speed
Joughin and MacAyeal (2005)
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Tidal motion of Whillians Ice Stream
Bindschadler et al (2003)
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Tidal movement of Brunt Ice Shelf
Doake et al (2002)
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Results from Nascent
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Nascent location
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Geodetic GPS
Tidal motion, horizontal displacement
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Tidal motion, vertical displacement
Geodetic GPS
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Ice flow speed
Geodetic GPS
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12 hour filtered lat-lon position, Garmin GPS
11/07 11/14 11/21
-78.1368
-78.1367
-78.1366
-78.1365
-78.1364
-78.1363
Latit
ude,
o S
Date
11/07 11/14 11/21175.5047
175.5048
175.5049
175.505
175.5051
175.5052
175.5053
175.5054
Long
iture
, o W
Date
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Thomas and MacAyeal (1982)
Ross Ice Shelf velocity
Nascent
V ~ 1095 m/yr10% higher?
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Questions:Tidal influence on ice shelf velocity
– Origin for ice stream stick/slip behavior?Speed up relative to 30 years ago (by
10%)?– Due to Joughin effect?– Due to acceleration of Ice Shelf?
Driver of rift propagation– If not background stress, then tide?
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Rift does not open 90m/yr as required by Joughin effect
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Tidal rift opening?