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History Antarctic Glaciology (Oversnow Traverses Late 50s/early 60s…
History Antarctic Glaciology
Airborne radar surveying
~ Ten year programme 69-79
First continental scale survey
Provided info on surface & bed elevation
Key discovery:
Much of WAIS sits on bed
below
sealevel
First elevation maps
From assembled radar seismic & gravity msmts e.g. Weertman 1974
∴ WAIS = biggest threat to global sealevel
'weak underbelly of antarctica'
forcing in AIS - will see WAIS decline/go away most quickly
Indicated WAIS = unstable
Marine
ice sheet
= area of ice with bed lying
below
sealevel
~ sensitive situation
Glaciological Expeditions
Antarctic field season = Nov-Jan/Feb
First glaciological expeditions ~1957-1958
History recap
1960s
Oversnow traverses
= Reconnaisance / exploration
1970s
Airborne reconn
First elev maps
∴ Ice volume --> WAIS Instability hypothesis
1980s/90s
Major field campaigns
Focus: WAIS instability hypothesis
1990s
Little evidence for WAIS instability
No measurements from Amundsen & Bellingshausen Seas though
Polar year (IGY)
recognition of polar expeditions
concerted global effort to make obvs of:
terrestrial magnetism
cosmic radiation
weather
Coincided w heightened sunspot activity
Focussed @ poles where atmos = thinner
Scientific Bases
Marginal locations
= where building can be erected on rock & are more accurate
Exceptions
Amundsen Scott base
@ S.Pole
Vostok - Russian base
V flat area - by chance atop lake
Marked move away from expeditions
allowed further study from continent, not ship
Antarctic Treaty
1961
= Proposal Antarctic continent should be
preserved for peace & scientific investigation
Suspended all land claims
i.e. no country owns it
44 countries signed treaty (80% global pop)
British Bases
Rothera
Halley
Oversnow Traverses
Late 50s/early 60s
First dedicated scientific traverses
Across Antarctica by caterpillar vehicles
Over 2 months of daylight in Austral summer
No remote sensing /aerial photos
To look ahead for crevases/ safe to proceed
∴ people up front using radar to look ahead
First msmts of:
Ice surface elevation
Ice depth (seismic, gravity)
Surface snow properties:
density, crystal size from snowpits
Downside
Sparse spatial coverage
Could not monitor ∆
Need for more
remote
means of taking msmts
National Focus
European
Filchner Ronne Ice shelf - Weddell Sea Sector
Beside Ellsworth Mountains ∴ install equipment on rock nr ice
USA
Ross ice shelf + Siple Coast ice streams
Ross Sea Sector
Directed Field Campaigns 1980s
Focus efforts on coordinated scientific experiments
Weddell Sea Sector
European
Began field msmt @ Rutford Ice Stream
Rutford ice stream drains into Filchner Ronne Ice Shelf
Spot msmts:
ice shelf thinning
weddell seas oceanography
Siple Coast
USA
Ice streams
Most ice Q
self-organised into fast flowing channels of ice
Separated by slower areas of ice flow
Test bed for ideas of basal motion (basal sliding, soft sed def)
Discovery:
Ice streams exhibit
cycles of rapid/slow motion
- 'surges'