Integrated Trends in Annual Accumulation Across West Antarctica from Operation IceBridge Snow Radar
Abstract
Accumulation rates in West Antarctica (largely synonymous with ice sheet surface mass balance) have important implications for ice sheet dynamics, sea level rise, and Southern Hemisphere polar climatology. The remote location and harsh environments of polar regions, however, make collection of in-situ accumulation measurements challenging, with insufficient coverage to adequately capture the high spatiotemporal variability present over the West Antarctic Ice Sheet (WAIS). Previous studies have demonstrated the efficacy of super-high frequency ice penetrating radar to image near-surface annual firn layers in dry-firn polar regions, highlighting the potential for additional and geographically-distributed estimates of annual accumulation. NASA's Operation IceBridge has collected such radar imaging extensively in West Antarctica, but to date no studies have presented an integrated picture of annual surface mass balance across the WAIS using these IceBridge data. Here we present estimates of annual accumulation over the dry firn zones of West Antarctica derived from Operation IceBridge Snow Radar echograms. We use a probabilistic automated layer extraction method combined with firn depth-density estimates from a Gaussian process regression model (informed by in-situ density measurements) to generate annual accumulation estimates to a depth of 25 m. Mean uncertainties in annual accumulation using this method are ~25% of the long-term local mean accumulation rate. We apply these methods to Operation IceBridge Snow radar data in West Antarctica collected 2009-2016, spanning 100,000+ km of radar transects and generating ~5,000,000 individual accumulation time series. We present spatiotemporal patterns and trends in annual accumulation locally and regionally over recent decades for the WAIS, and evaluate the climate mechanisms driving the observed changes. These results permit improved understanding of the dominant climatic controls on Antarctic precipitation, and will allow for improved validation of polar climate models and better estimates of the current and future offset of sea level rise from changes in Antarctic precipitation patterns.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.C31C1561K
- Keywords:
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- 3360 Remote sensing;
- ATMOSPHERIC PROCESSES;
- 0726 Ice sheets;
- CRYOSPHERE;
- 0750 Sea ice;
- CRYOSPHERE;
- 4556 Sea level: variations and mean;
- OCEANOGRAPHY: PHYSICAL