Please enable JavaScript.
Coggle requires JavaScript to display documents.
Removal Ice from Ice Shelves 2 (Ice shelf circulation patterns…
Removal Ice from Ice Shelves 2
Ice shelf
circulation
patterns
Circulation in mixed layer
ocean flow directly beneath ice shelf
Flow along
base ice shelf
i.e. from g.l. seaward as ice shelf shallows
Flow deflected
to one side
due to Coriolis force
∴ Water exits along ice shelf margin
& sometimes melting occurs here too
Little et al 2009 Simulated:
temp ocean beneath shelf
melt rate pattern
circulation / ocean flow in mixed layer
Mixed
Layer
Top 10-20 m water immediately beneath ice shelf
= responding to melt & mixing etc
Why melting along ice shelf margin
?
Melting along ice shelf margin
despite low temps & surface f.p.
How?
Fast flow can heighten melt rates
Not only temp dictating melt rates...
Why melting may not be sustained
As melt proceeds:
Thin, cold freshwater layer grows below ice-ocean interface
∴ Shields ice from heat/salt effects & inhibits melt
Unless cold water = mixed away
To sustain
high melt rates:
Holland & Jenkins 1999
Warm (salty) water is not enough
Turbulence = required to:
Mix cold freshwater away from ice-ocean interface
Entrain warm water into mixed layer
(to maintain heat supply)
(otherwise it shields ice from melt)
Fast flow @ ice-ocean interface
= required to drive turbulence
Effect of shelf melting on ice sheets
Different ocean temps beneath shelf yield different:
Melt rates
Grounding line retreat extent
Sea level contribution
Unexpected findings:
Grounding line retreat varies
Expected findings: Melt rates = higher when temps higher
Disproportionate
g.l. retreat
0 - 0.6°C = Small retreat g.l.
1.2 - 1.8 °C = Larger g.l. retreat (15-20 km.)
Goldberg
et al 2012 Study
Does it mattter WHERE melting occurs ?
Coupled ice-ocean model - glued so interact
Varied ocean temps - interior layers 0 - 1.8°C
Observed how grounded ice loss changes
Sea level contribution
Reflects grounded ice volume loss
Small rise loss grounded ice
for cold - medium warm experiments (0, 0.6, 1.2 °C)
Massive increase loss grounded ice
for v. warm scenerio (1.2 - 1.8°C)
What's distinct about 1.8°C scenerio?
✓ Melting location
= important
x No signif difference overall ice shelf loss/melt
Melting strongest in top W margin
Coriolis causes pile up mixed layer flow at W margin
Focussed eat & fast flow melted through margin
∴ Buttressing lost from W margin ice shelf