The Flow of Dense Water Plumes in the Western Weddell Sea Simulated with the Finite Element Ocean Model (FEOM) - Towards an Interdisciplinary Approach in Earth System Science - page 116

(WDW) or by the interaction of shelf waters with WDW (e.g. Nicholls et al. 2009 ).
As the current flows north along the isobaths, dense waters observed on the con-

tinental shelf in front of the Larsen Ice Shelf (LIS)

fl

flow down the slope mixing with
the ambient waters and increasing the volume of WSDW (e.g. Absy et al. 2008 ).
As the current reaches the tip of the AP it turns east along the South Scotia Ridge
and forms the northern branch of the gyre. Through a passage in the Powell Basin,
the Philip Passage, or one of the deep gaps in the South Scotia Ridge, Orkney
Passage, Bruce Passage, and Discovery Passage, the WSDW escapes from the
Weddell Sea to form AABW (e.g. Naveira Garabato et al. 2002 ).
As mentioned before, part of the shelf water is deviated to the west and enters the
Brans

fl

eld Strait. There, the relatively cold and salty Weddell Sea waters mix with
water masses from the Antarctic Circumpolar Current and from the Bellingshausen
Sea,

filling almost the entire Strait. One assumes that the Brans eld Deep Water is a

mixture of Weddell shelf waters with WDW modi ed by in situ winter conditions

(Garc a et al. 2002 ).

In the present work we investigate how changes in the characteristics of the
dense shelf waters observed off LIS may impact the neighboring basins. To reach
this goal we used numerical simulations performed with the Finite Element Ocean
Model (FEOM).

í

2 Model Setup and Experiments

FEOM is a 3D finite-element primitive equation ocean circulation model based on

an unstructured horizontal mesh. The version used in this study is fully described by
Wang et al. ( 2008a ). For our experiments a triangular grid that goes from 25 to 80

S
and encircles the Antarctic Continent was created. The surface mesh resolution
varies from 1/15

°

° (approx. 3.3 km) in the area of investigation, i.e. the western

Weddell Sea, to 2 ) vertical levels

with increased resolution close to the bottom and in the surface mixed layer were
used (Wang et al. 2008b ). The bathymetry was derived from the 2-Minute Gridded
Global Relief Data (ETOPO2 2001 ).
To the south the continent limits the domain, and for the northern open boundary
a restoring of temperature and salinity to climatological values from the World
Ocean Atlas 1994 (WOA01) (Levitus and Boyer 1994 ) was used along 15

° in the remaining areas. 21 terrain-following (

σ

° of

latitude. The model was initialized with mean temperature and salinity fields

extracted from WOA01 and forced with the wind stress from the National Centers
for Environmental Predictions (NCEP) reanalysis (see e.g. Trenberth et al. 1990 ),
and sea surface temperature and salinity were relaxed to the WOA01 values. After
4.5 years of integration the model was stable and we initialized the out

fl ow

experiments.