Winter mixed-layer development in the central Irminger Sea : the effect of strong, intermittent wind events
MetadataShow full item record
LocationSouthwest Irminger Sea
The impact of the Greenland tip jet on the wintertime mixed-layer of the southwest Irminger Sea is investigated using in-situ moored profiler data and a variety of atmospheric data sets. The mixed-layer was observed to reach 400 m in the spring of 2003, and 300 m in the spring of 2004. Both of these winters were mild and characterized by a low North Atlantic Oscillation (NAO) index. All of the storms that were advected through the region were tracked, and the tip jet events that occurred throughout the two winters were identified. Composite images of the tip jets elucidated the conditions during which tip jets were likely to take place, which led to an objective method of determining tip jet occurrences by taking into account the large-scale pressure gradients. Output from a trajectory model indicates that the air parcels entering a tip jet accelerate and descend as they are deflected around southern Greenland. A heat flux timeseries for the mooring site was constructed that includes the enhancing influence of the tip jet events. This was used to drive a one-dimensional mixed-layer model, which was able to reproduce the observed mixed-layer deepening in both winters. All of the highest heat flux events took place during tip jets, and removal of the tip jets from the heat flux timeseries demonstrated their importance in driving convection east of Greenland. The deeper mixed-layer of the first winter was in large part due to a higher number of robust tip jet events, which in turn was caused by a greater number of storms passing northeast of southern Greenland. This interannual change in storm tracks was attributable to a difference in upper level steering currents. Application of the mixed-layer model to the winter of 1994-l995, during a period characterized by a high NAO index, resulted in convection reaching 1600 m. This predict ion is consistent with concurrent hydrographic data, supporting the notion that deep convection can occur in the Irminger Sea during strong winters.
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2006
Suggested CitationThesis: Våge, Kjetil, "Winter mixed-layer development in the central Irminger Sea : the effect of strong, intermittent wind events", 2006-09, DOI:10.1575/1912/1775, https://hdl.handle.net/1912/1775
Showing items related by title, author, creator and subject.
Moulton, Melissa (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2016-06)Holes and channels were excavated in the surf zone on an ocean beach near Duck, NC, and observations of the subsequent evolution of waves, currents, and the modified seafloor were used to investigate nearshore dynamics. ...
Sosa, Oscar A. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2016-06)Microorganisms play a central role mediating biogeochemical cycles in the ocean. Marine dissolved organic matter (DOM) – a reservoir of organic solutes and colloids derived from plankton is a major source of carbon, ...
Vilasur Swaminathan, Rohith (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2016-06)In this thesis, we have studied the existence of vortex steady states in a sinusoidal background shear flow in a 1.75 layer quasi-geostrophic model. Trying to find vortex structures by integrating the Hamiltonian system ...