An Investigation into the dynamics of the ocean current system off southern Greenland

The ocean current system off Southern Greenland is a key component of the Earth’s<br/>climate system due to its role in the regulation of the global thermohaline<br/>circulation. A combination of historic and new observational data, supported by<br/>modelling simulations, has revealed great complexity in both the surface and deep<br/>currents of the area. A comprehensive review of the available hydrographic data for<br/>the South-East Greenland shelf has shown that the observed spatial variability in the<br/>transport of the on-shelf East Greenland Coastal Current is inconsistent with the<br/>theory that it is primarily driven by local fjord runoff. A high resolution regional<br/>modelling study supports these observations and suggests that the East Greenland<br/>Coastal Current is primarily the result of a bifurcation of the East Greenland Current<br/>in the vicinity of Denmark Strait. Model simulations also suggest that the pathways<br/>followed by the low salinity output of the region’s fjord complexes are influenced<br/>by the strength and position of the main East Greenland Current. New data collected<br/>in the vicinity of Cape Farewell, on the southern tip of Greenland, has also revealed<br/>more complex behaviour in the Deep Western Boundary Current. The significant<br/>spatial variability in Deep Western Boundary Current transport observed in the<br/>region of Cape Farewell suggests that the confluence of Denmark Strait Overflow<br/>Water and Iceland Scotland Overflow Water occurs over a wider geographic area<br/>than is commonly suggested. A review of historic data indicates that these spatial<br/>patterns vary over timescales of months and upwards. It is hypothesised that strands<br/>of overflow water follow different depth controlled pathways dependent on their<br/>relative water density in comparison with the surrounding water masses. This has<br/>significance for the way deep current strength proxies in the region are interpreted in<br/>relation to climatic variations. Time series data for a single location may well<br/>overestimate the variability in the Deep Western Boundary Current further south due<br/>to path switching of the flow. In the future more complete observational datasets<br/>combined with more advanced oceanographic and coupled climate models will<br/>provide a better understanding of the interaction between the regional current<br/>system, the global current system and the climate system. This will enable more<br/>reliable prediction of the impact of global warming and, in particular, the potential<br/>influence of accelerated Greenland ice cap melting on the global ocean circulation.

Name dc:type.qualificationname

Ph.D.

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Southampton

Year dc:date.issued

2008

Author dc:creator

• Wilkinson, D.