期刊
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
卷 119, 期 2, 页码 153-167出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2013JF002915
关键词
tidewater glaciers; Alaska; glacier change
资金
- NSF [EAR-0943742]
- NASA [NNX11AF41G, NNX11A023G]
- Directorate For Geosciences
- Division Of Earth Sciences [0943599] Funding Source: National Science Foundation
- NASA [NNX11AF41G, 146247] Funding Source: Federal RePORTER
A significant portion of the world's glacier ice drains through tidewater outlets, though much remains unknown about the response to recent climate change of tidewater glaciers. We present a 64 year record of length change for 50 Alaska tidewater glaciers. We use U.S. Geological Survey topographic maps to provide a base length for glaciers before 1970. Using all available cloud-free Landsat images, we manually digitize calving front outlines for each glacier between 1972 and 2012, resulting in a total of more than 10,000 outlines. Tidewater glacier lengths vary seasonally; focusing on the 36 glaciers terminating in tidewater throughout the study period, we find a mean ( standard deviation) seasonal variation of 60 85m a(-1). We use these oscillations to determine the significance of interannual changes in glacier length. All 36 glaciers underwent at least one period (1 year) of significant advance or retreat; 28 glaciers underwent at least one period of both significant advance and retreat. Over the entire period 1948-2012, 24 of these glaciers retreated a total ( uncertainty) of 107.950.29 km, 11 advanced a total of 7.71 +/- 0.20, and one (Chenega Glacier) did not change significantly. Retreats and advances are highly variable in time; several glaciers underwent rapid, short-term retreats of a few years duration. These retreats occurred after large changes in summer sea surface temperature anomalies; further study is needed to determine what triggered these retreats. No coherent regional behavior signal is apparent in the length record, although two subregions show a coherence similar to recent observations in Greenland.
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