| View Larger Image | Diatom oxygen isotopes in pro-glacial lake sediments from northern Sweden: a 5000 year record of atmospheric circulation [An article from: Quaternary Science Reviews] | Digitalby G. Rosqvist (Author), C. Jonsson (Author), R. Yam (Author), W. Karlen (Author), Shemes (Author)
| List Price: | $5.95 | | | Available: | Available for download now |
| | Binding: | Digital | | Publisher: | Elsevier | | Publication Date: | April 01, 2004 |
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Product Description
This digital document is a journal article from Quaternary Science Reviews, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.Description: We use a pro-glacial oxygen isotope record of diatom silica (@d^1^8O"d"i"a"t"o"m) and a sedimentary proxy for glacier fluctuations to determine centennial-millennial scale climate change during the last 5000 years in northern Sweden. We show that the lake water isotopic composition predominantly reflects the isotopic composition of the precipitation. Superimposed on a general depletion trend of 3.5%% over the past 5000 years we found that the isotopic composition of precipitation became depleted (>1%% excursions) during four occasions centered at 4400, 3000, 2000, and after 1200calyr BP. Climate simultaneously sustained a positive glacier mass balance, that caused the catchment glacier to advance. A persistent change in the atmospheric circulation pattern could potentially have caused the registered changes in @d^1^8O"d"i"a"t"o"m because different air masses hold characteristic @d^1^8O signatures of their precipitation. The glacier mass balance primarily responds to the influence of summer temperature on ablation. We suggest that the most likely cause for the recorded changes in both these proxies is a steadily increasing but fluctuating dominance of colder and @d^1^8O depleted air masses from the north/northeast during the past 5000 years. The @d^1^8O"d"i"a"t"o"m depletion and glacier events all occur at times of relative ice-rafted-debris maxima in the North Atlantic, consistent with cold conditions and changes in surface wind directions. Our results confirm that changes towards a predominance of north/northeasterly winds occurred at these time intervals. |
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