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| Titel |
Sub-decadal Norwegian Coastal Current variability expressed in XRF Ca/Fe content in the SE Norwegian Sea |
| VerfasserIn |
Heidi Kjennbakken, Haflidi Haflidason, Hans Petter Sejrup, Scott J. Lehman |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250046268
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| Zusammenfassung |
| The lack of accurately dated marine records has made it difficult to generate a regional
reconstruction of high-frequency paleoclimatic variability. This study presents a well-dated
high-resolution record, which can be used as a step towards that regional reconstruction. The
objectives of this study are to develop a better understanding of the X-ray Fluorescence
(XRF) Ca/Fe record and to use this knowledge to reconstruct paleoceanographic variability
in the SE Norwegian Sea. The XRF core scanning analyses were preformed on a
multi-core (P1-003MC-tubeB) from the upper continental slope (850 m depth) in the SE
Norwegian Sea. A precise chronology was established utilizing 210Pb, tephra and a 14C
wiggle-match method and the record spanned from 1450 AD to 1994 AD with
annual to subdecadal resolution (Sejrup et al., in press). The XRF Ca/Fe results
most likely reflect coccolithophorid abundance, which is particularly high in the
Norwegian Coastal Current (NCC) waters. We suggest that higher Ca/Fe ratios
may reflect NCC water extending over the core site in the spring/summer season,
during the coccolithophorid bloom. The westward extension of the NCC is related
to atmospheric forcing, where weak northerly winds cause the NCC to shoal and
extend further west, increasing the coccolithophorid abundance over the core site.
When the northerly winds are anomalously strong, enhanced vertical mixing erodes
the vertical stratification of the NCC, which mixes into the underlying Atlantic
waters, causing lower coccolithophorid abundance. A pronounced decrease in the
Ca/Fe ratio is recorded during the Dalton solar minimum. From our hypothesis, this
suggests less NCC water over the core site, possibly due to stronger spring/summer
winds. A correlation of the Ca/Fe ratio to the sea surface temperature and the North
Atlantic Oscillation were detected; the understanding of these dynamics is work in
progress.
Reference:
Sejrup, H. P., S. J. Lehman, H. Haflidason, D. Noone, R. Muscheler, I. M. Berstad, and J.
T. Andrews (in press), Response of Norwegian Sea temperature to solar forcing
since 1000 A.D., Journal of Geophysical Research, doi:10.1029/2010JC006264 |
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