Sources of Eddy Kinetic Energy in the Labrador Sea
- 1 December 2002
- journal article
- Published by American Meteorological Society in Journal of Physical Oceanography
- Vol. 32 (12), 3346-3363
- https://doi.org/10.1175/1520-0485(2002)032<3346:soekei>2.0.co;2
Abstract
Experiments with a suite of North Atlantic general circulation models are used to examine the sources of eddy kinetic energy (EKE) in the Labrador Sea. A high-resolution model version (112°) quantitatively reproduces the observed signature. A particular feature of the EKE in the Labrador Sea is its pronounced seasonal cycle, with a maximum intensity in early winter, as already found in earlier studies based on altimeter data. In contrast to a previously advanced hypothesis, the seasonally varying eddy field is not related to a forcing by high-frequency wind variations but can be explained by a seasonally modulated instability of the West Greenland Current (WGC). The main source of EKE in the Labrador Sea is an energy transfer due to Reynolds interaction work (barotropic instability) in a confined region near Cape Desolation where the WGC adjusts to a change in the topographic slope: Geostrophic contours tend to converge upstream of Cape Desolation, such that the topographically guided WGC narrows as well and becomes barotropically unstable. The eddies spawned from the WGC instability area, dominating the EKE in the interior Labrador Sea, are predominantly anticyclonic with warm and saline cores in the upper kilometer of the water column, while the few cyclones originating as well from the instability area show a more depth-independent structure. Companion experiments with a ⅓° model exhibit the strength of the WGC, influenced by either changes in the wind stress or heat flux forcing, as a leading factor determining seasonal to interannual changes of EKE in the Labrador Sea.Keywords
This publication has 37 references indexed in Scilit:
- Labrador Sea Boundary Currents and the Fate of the Irminger Sea WaterJournal of Physical Oceanography, 2002
- Sea surface height changes in the North Atlantic Ocean related to the North Atlantic OscillationGeophysical Research Letters, 2001
- Mechanism of Interannual to Decadal Variability of the North Atlantic CirculationJournal of Climate, 2001
- Thermal forcing for a global ocean circulation model using a three-year climatology of ECMWF analysesJournal of Marine Systems, 1995
- TOPEX/POSEIDON: The 2‐cm solutionJournal of Geophysical Research: Oceans, 1994
- Effects of Increased Horizontal Resolution in a Simulation of the North Atlantic OceanJournal of Physical Oceanography, 1994
- Eddy Dynamics in a Primitive Equation Model: Sensitivity to Horizontal Resolution and FrictionJournal of Physical Oceanography, 1992
- Sensitivity of the GFDL Ocean General Circulation Model to a Parameterization of Vertical DiffusionJournal of Physical Oceanography, 1990
- The Formation of Labrador Sea Water. Part I: Large-Scale ProcessesJournal of Physical Oceanography, 1983
- A seasonal signal in ocean currents to abyssal depthsNature, 1982