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| Titel |
Analysis of trends in coastal upwelling variability during the late 20th century |
| VerfasserIn |
N. Narayan, A. Paul, S. Mulitza, M. Schulz |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250024586
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| Zusammenfassung |
| This study presents linear trends of coastal upwelling intensity in the later part of the 20th
century (1960-2001) employing various indices of upwelling, derived from meridional wind
stress, sea surface temperature and surface chlorophyll concentration. The analysis was
conducted in the four major coastal upwelling regions in the world which are off
North-West Africa, off Lüderitz, off California and off Peru. We also did a correlation
analysis of the upwelling indices with basin-scale oscillations like the North Atlantic
Oscillation (NAO), the Atlantic Multi-decadal Oscillation (AMO) and the Pacific
Decadal Oscillation (PDO). The correlation at different lags was estimated using
cross-correlation. As a result the trends in meridional wind stress showed a steady
increase of intensity from 1960-2001, which was also reflected in the SST index
calculated for the same time period. The steady cooling observed in the instrumental
records of SST off California substantiated this observation further. The correlation
analysis also showed that the basin-scale oscillations like AMO and PDO cannot be
directly linked to the observed increase of upwelling intensity off NW Africa and
California respectively. The relationship of NAO with coastal upwelling off NW Africa
seems to be ambiguous due to a negative correlation between the NAOI and the
meridional wind stress and a lack of correlation with the SST index. Our results give
additional support to the hypothesis that the coastal upwelling intensity increases
globally because of raising greenhouse gas concentrations in the atmosphere and a
subsequent increase of the land-sea pressure gradient and meridional wind stress. |
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