The shape of change: A new method to identify sources of dynamic thickness change
Abstract
The past few decades have brought an abundance of observations covering much of our changing ice shelves. However, it remains a challenge to interpret these observations without reliable frameworks. For example, the Ross Ice Shelf's (RIS) thickness has been observed to change at varying rates in different locations. Imprinting on that signal is thickness change from past flow changes of ice shelf tributaries, a type of internally driven variability. Another part of thickness change signal represents responses to external forcings, such as changes to surface accumulation and basal melting. Further complicating this process, is the satellite record is discontinuous in space and time, we therefore require a method to distinguish these sources under that constraint. We present a new method, called response surface analysis, that correctly attributes observations to past variations to ice shelf tributary flow. We apply empirical orthogonal function analysis to model data to generate response surfaces, which are fundamental spatial patterns for ice shelf response to tributary flux changes. Using response surfaces, we are able to determine the extent to which past flow variations are imprinting the present-day thickness change signal measure by ICESat satellite altimetry. Our response surface approach correctly identifies the magnitude and timing know past flow variations such as the Kamb Ice Stream shutdown, Whillans Ice Stream slowdown and Byrd Glacier acceleration. Other methods have separated thickness change observations into mass-balance changes and dynamic changes. Our method is distinguished from those methods in that we separate by source, acknowledging that both mass-balance driven and dynamic changes produce dynamic responses that evolve over time. Our new method makes specific predictions how dynamic signals will evolve over time, suiting discontinuous time series of observations.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.C51B0984C
- Keywords:
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- 0728 Ice shelves;
- CRYOSPHERE;
- 0746 Lakes;
- CRYOSPHERE;
- 0762 Mass balance 0764 Energy balance;
- CRYOSPHERE;
- 0774 Dynamics;
- CRYOSPHERE