Masters Thesis Defense by Kaija Jumppanen Andersen – Niels Bohr Institutet - Københavns Universitet

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Masters Thesis Defense by Kaija Jumppanen Andersen

Abstract: Several studies have shown a connection between the currents in the North Atlantic and the state of the North Atlantic Oscillation (NAO), which is determined from the atmospheric pressure anomalies in the area. Most of these studies use in-situ measurements, models, or short time scales when determining the connection between the atmosphere and currents. This results in relatively large uncertainties in the correlation between the two systems.

In this study satellite measurements of the sea surface topography are used to determine anomalies in the geostrophic surface currents. These anomalies are then compared with anomalies in the atmospheric surface pressure. Satellite data are used, as continued measurements of the sea surface are available in the period from January 1992 to August 2012. This comparison shows that during a positive NAO, the southward East Greenland Current weakens, while the southward East Iceland Current and the northward Norwegian Current strengthens. The Irminger Current and North Atlantic Current do not seem to be affected in strength, but possibly a little in location.

Establishment of a connection between the state of the atmosphere and the currents allows a simple model of the currents to be developed. This model can estimate the current from the anomalies in the atmospheric pressure. The model performs well in the winter months, where the current can be estimated with a correlation coefficient of up to 0.7 between the data and the model for the best model determined with independent data.