Elin Darelius
Researcher in Physical Oceanography
Geophysical Institute, University of Bergen
Bjerknes Centre for Climate Research
Norway

Research

polar oceanography
dense overflows
plume dynamics

In the present climate, all deep oceans are filled with cold water originating at high latitudes. Cooling and salinification through freezing and brine rejection in polar regions produce cold, dense water masses that sinks and eventually flow equatorward at depth. Meanwhile, light and warm surface water flows poleward, cloosing the (much simplified) loop that is commonly referred to as the thermohaline circulation (THC). The THC transports heat poleward, and has a central role in climate. Dense water "spilling over" from one ocean basin to another, will flow out along the continental slope as a dense plume. These overflow sites are regions of major water mass transformation, since lighter, ambient water is entrained into the plume, and important links in the THC. Despite their importance, much of the internal physics and dynamics of these flows are unknown. An understanding of overflows, plumes, and the related processes is an necessity if one seeks to understand and predict our changing climate.

Filchner Overflow, Antarctica; The Filchner Overflow was detected in 1977, when hydrographic sections from the continental slope in the southwestern Weddell Sea revealed a plume of dense, supercooled water emerging from the Filchner depression. The plume consists of Ice Shelf Water (ISW) originating from the Filchner-Ronne Ice Shelf cavity, where it has been cooled from contact with glacial ice at great depth. On the continental slope, the ISW mixes with the ambient water to form Weddell Sea Bottom Water and evenually Antarctic Bottom Water (AABW). AABW occupies a major part of the deep ocean. In my PhD, I analysed data from current meter moorings in the outflow region. We focussed on small-scale variability, and revealed oscillations in the velocity and temperature records with periods of 1.5, 3 and 6 days, that existent theories are unable to explain. We also synthesised all available CTD-data.

Topographic Steering; Due to the earth'r rotation (the Coriolis force), dense plumes will tend to flow along the slope in geostrophic balance. Canyons - and as shown in my PhD-thesis - also ridges cross-cutting the slope, may break this balance and steer plume water down the slope. In my PhD I applied an analytical model to describe the dynamics of these flows, and I further explored flow in canyons/along ridges in laboratory experiments, which I performed at the Geophysical Fluid Dynamics Laboratory, University of Washington and at the rotating Coriolis platform in Grenoble, France.

I am currently involved in the IPY project "Bipolar Thermohaline Atlantic Circulation" (BIAC). I am working at the Geophysical Institute, UiB and attached to the Bjerknes Centre for Climate Research. I am a former UNIS-student.

Publications
Curriculum Vitae (CV)

Address

Elin Darelius
Office: Østfløyen 301 
Geophysical Institute 
Allégaten 70, 5007 Bergen, Norway 

Phone: +47 55 58 87 95 
Fax:     +47 55 58 98 83 
Email: elin@gfi.uib.no
Web: www.uib.no/People/gbsed/
Updated 3 December 2007