Classifying sub-ice shelf morphology around West Antarctica, using Operation IceBridge aerogravity
Abstract
Over the last decade Operation IceBridge has flown extensive aerogravity surveys over both Antarctica and Greenland in order to map the seafloor bathymetry beneath otherwise inaccessible regions of floating ice. Using the SGL AIRGrav system, gravity anomalies have been mapped to ~1 mGal accuracy around the entire grounding line of West Antarctica. Ocean-ice interactions near the grounding line are a major factor in the stability of the ice sheets. Accurate knowledge of the seafloor bathymetry is therefore an important boundary condition in ice sheet models.
We have performed inversions of gravity anomaly data from major ice shelves around West Antarctica, using OIB ice thickness and surface elevations as constraints on ice shelf geometry. Complex ocean circulation routes have been discerned within the sub-ice-shelf cavities as well as evidence of geological conditions in front of the present day grounding line, including outcropping crystalline basement highs and sedimentary basins that record past glacial activity. In general, sub-ice shelf cavities are dominated either by geological structure, or glaciological geomorphology. This distinction is significant for ice sheet history. Where glaciological structures dominate the landscape, troughs cut from the continental shelf edge to the grounding line can transport warm water across the continental shelf, leading to increased vulnerability to changing ocean states. Where geological structure dominates, landscape trends need not align with glaciological flow paths, and more obstructions to ice and water flow exist. We present a synthesis of new bathymetry revealed from Operation IceBridge surveys, and classify ice shelves according to the dominant characteristics of their geomorphology. These classifications can be used for understanding past ice sheet behavior, locating sediment records of former climate states and predicting the future stability of the Antarctic ice sheet.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.C43B..06T
- Keywords:
-
- 3360 Remote sensing;
- ATMOSPHERIC PROCESSES;
- 0726 Ice sheets;
- CRYOSPHERE;
- 0750 Sea ice;
- CRYOSPHERE;
- 4556 Sea level: variations and mean;
- OCEANOGRAPHY: PHYSICAL