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Importance of the mesoscale in the decadal changes observed in the northern Canary upwelling system

Publication . Relvas, Paulo; Luis, Joaquim; Santos, A. Miguel P.

Analysis of sea surface temperature (SST) time series since 1960 from existing data bases shows a generalized warming trend in the northern Canary upwelling system. The field of the satellite-derived SST trends off Western Iberia was built at the pixel scale (4 x 4 km) for the period 1985-2008, revealing significant spatial differences in the warming rates. Weaker warming trends fit to the known upwelling pattern off the southern part of the Western Iberia, pointing out the intensification of this feature since 1985, particularly during the peak summer months. A more regular behavior is found further north suggesting significant decadal changes in the mesoscale patterns of the northern Canary upwelling system. Citation: Relvas, P., J. Luis, and A. M. P. Santos (2009), Importance of the mesoscale in the decadal changes observed in the northern Canary upwelling system, Geophys. Res. Lett., 36, L22601, doi:10.1029/2009GL040504.

2018-06Journal article

Open Access

A spatiotemporal reconstruction of sea-surface temperatures in the North Atlantic during Dansgaard-Oeschger events 5-8

Publication . Jensen, Mari F.; Nummelin, Aleksi; Nielsen, Soren B.; Sadatzki, Henrik; Sessford, Evangeline; Risebrobakken, Bjorg; Andersson, Carin; Voelker, Antje; Roberts, William H. G.; Pedro, Joel; Born, Andreas

Here, we establish a spatiotemporal evolution of the sea-surface temperatures in the North Atlantic over Dansgaard-Oeschger (DO) events 5-8 (approximately 3040 kyr) using the proxy surrogate reconstruction method. Proxy data suggest a large variability in North Atlantic sea-surface temperatures during the DO events of the last glacial period. However, proxy data availability is limited and cannot provide a full spatial picture of the oceanic changes. Therefore, we combine fully coupled, general circulation model simulations with planktic foraminifera based seasurface temperature reconstructions to obtain a broader spatial picture of the ocean state during DO events 5-8. The resulting spatial sea-surface temperature patterns agree over a number of different general circulation models and simulations. We find that sea-surface temperature variability over the DO events is characterized by colder conditions in the subpolar North Atlantic during stadials than during inter-stadials, and the variability is linked to changes in the Atlantic Meridional Overturning circulation and in the sea-ice cover. Forced simulations are needed to capture the strength of the temperature variability and to reconstruct the variability in other climatic records not directly linked to the seasurface temperature reconstructions. This is the first time the proxy surrogate reconstruction method has been applied to oceanic variability during MIS3. Our results remain robust, even when age uncertainties of proxy data, the number of available temperature reconstructions, and different climate models are considered. However, we also highlight shortcomings of the methodology that should be addressed in future implementations.

2009-11Journal article

Open Access