Annual accumulation at two sites in northwest Greenland during recent centuries
| Autor: | Roger C. Bales, Martin Anklin, Konrad Steffen, Ellen Mosley-Thompson |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Atmospheric Science
Soil Science Aquatic Science Oceanography Water equivalent Ice core Geochemistry and Petrology Earth and Planetary Sciences (miscellaneous) Earth-Surface Processes Water Science and Technology geography geography.geographical_feature_category Ecology biology Firn Paleontology Forestry Glacier biology.organism_classification Geophysics Space and Planetary Science Period (geology) Spatial variability Groenlandia Geology |
| Zdroj: | Journal of Geophysical Research: Atmospheres. 103:28775-28783 |
| ISSN: | 0148-0227 |
| DOI: | 10.1029/98jd02718 |
| Popis: | During summer 1995, 150-m firn and ice cores were drilled to determine annual accumulation rates at two Greenland sites, 73.84°N, 49.49°W (NASA-U site) and 78.53°N, 56.83°W (Humboldt glacier site). Annual layers were identified in the cores using multiple parameters: δ 18 O and concentrations of dust, H 2 O 2 , NH 4 + , Ca 2+ , and NO 3 - . Using all parameters together to define annual layers resulted in a 350-year record for the NASA-U core with no dating uncertainty. For the lower-accumulation Humboldt core, the dating uncertainty is about 5 years over the 852-year period of record, with no uncertainty over the past 200 years. Annual accumulation over the periods of record at the two sites averaged about 0.34 and 0.14 m water equivalent, respectively. A set of 20-m firn cores drilled near the main 150-m cores showed that interannual variability of accumulation exceeded spatial variability at NASA-U. The Humboldt cores showed equal spatial and interannual variability. The accumulation rates at both sites showed a low-frequency variation of about 100 years, and both sites showed 200-year cumulative fluctuations of about 2 m from mean accumulation rates. Compared to central Greenland and to NASA-U, the Humboldt core showed higher annual accumulation rates around 1760-1810, possibly indicating a changed circulation pattern for the more northern part of Greenland in that period. |
| Databáze: | OpenAIRE |
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