slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
100 km PowerPoint Presentation
Download Presentation
100 km

Loading in 2 Seconds...

play fullscreen
1 / 12

100 km - PowerPoint PPT Presentation


  • 93 Views
  • Uploaded on

Disturbed Terrain in the Mouth of Kamb Ice Stream. G. Catania, H. Conway, C. Raymond and T. Scambos * Earth and Space Sciences, University of Washington, Seattle WA, 98195 * National Snow & Ice Data Center, University of Colorado, Boulder CO, 80309. Siple Dome. Many thanks to:

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about '100 km' - silas


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Disturbed Terrain in the Mouth of Kamb Ice Stream

G. Catania, H. Conway, C. Raymond and T. Scambos*

Earth and Space Sciences, University of Washington, Seattle WA, 98195

*National Snow & Ice Data Center, University of Colorado, Boulder CO, 80309

Siple

Dome

Many thanks to:

NSF support (OPP #9909518)

Raytheon Polar Services

A. Gades, M. Conway &

E. Waddington

Kamb Ice Stream

Stream

Ice

Whillans

100 km

Image from T. Scambos

slide2

Kamb Ice Stream: Disturbed terrains

Siple Dome

Duckfoot

KIS

Kamb Ice Stream

Engelhardt

Ridge

Stream

Goosefoot

Ice

WIS

100 km

Whillans

Image from T. Scambos

slide3

Disturbed Terrains: Duckfoot

Siple Dome

Duckfoot Syncline?

Duckfoot Syncline

KIS margin

(1849)

Siple Dome

Duckfoot Syncline?

KIS margin (1624)

MODIS

Duckfoot Syncline

Images: T. Scambos (NSIDC)

KIS margin (1624)

AVHRR

slide4

Duckfoot: Internal layers

Duckfoot Syncline

KIS margin (1624)

glitch

~2 MHz

Horizontal Distance (km)

slide5

Kamb Ice Stream: Disturbed terrains

Siple Dome

Duckfoot

Kamb Ice Stream

Engelhardt

Ridge

Stream

Goosefoot

Ice

100 km

Whillans

Image from T. Scambos

slide6

N

Disturbed Terrains: Goosefoot

Kamb Ice Stream

KIS margin (1859)

Goose

Syncline

Goose

Syncline

WIS margin (1859)

MODIS

Image from T. Scambos

slide7

Goosefoot: Internal Layers

Goose

Syncline

KIS margin (1859)

Goose Internal Boundary

~5 MHz

Horizontal Distance (km)

slide8

Syncline Feature

Disturbed Terrain

Syncline Features and Disturbed Terrains

Siple Dome

Kamb Ice Stream

Engelhardt

Ridge

Stream

Ice

100 km

Whillans

slide9

Syncline Feature

Syncline Features: Mechanisms

0.1 ma-1

↑Accumulation

  • Why does it melt in such a discrete zone?
  • Why does it melt at all?
  • Possible old grounding line?
    • high melt rates are associated with grounding lines (Rignot & Jacobs, 2002)
    • how far downstream is melt maintained?
    • what about other features?

↑Basal melt

0.1 ma-1

slide10

Disturbed Terrain

Ridge

BC

Deep Diffractors: Mechanisms

  • What are the diffractors?
  • Freeze-on ice?
    • up to 25 m thick on KIS (Engelhardt)
  • Relict basal crevasses?
    • form at boundary between grounded and floating ice (Jezek and Bentley, 1983).
    • kept open and enlargened by tidal flexure.

Could the lower end of KIS float?

slide11

Ice thickness in 1624 A.D.

Goosefoot: 25-32 m above floatation

Duckfoot: 47-61 m above floatation

Floatation??

BEDMAP

Disturbed Areas of KIS:

- Goosefoot: 60-103 m above floatation

- Duckfoot: 82-132 m above floatation

Possible changes since 1624 A.D.:

- accumulation ~ 17 m

- ridge expansion ~ 36 m (Nereson, 2000)

- isostatic rebound ~ 1? m (James, 1998)

- post-stagnation freeze-on ~1-2 m (Kamb, 2001)

- firn layer ~ 15.5 m (Bamber & Bentley, 1997)

- longitudinal compression ??

- sea level rise ~ 0.5 m

Conway

Ridge

Engelhardt Ridge

Siple

Dome

from Lythe et al. 2001

slide12

Summary:

  • Disturbed Terrains:
    • No fast flow features, no near-surface diffractors
    • Outside of ice stream boundaries
    • Deep diffractors (~1/2 H)
    • Distorted, continuous internal layers
  • Syncline Features:
    • Strongly downwarped isochrones
    • Amplitude increases with depth, basal melting
  • Floatation Criteria for Disturbed Terrain:
    • Requires an additional loss of ~30-60 m ice
    • Similar to WIS ice plain 400 years ago.