C. Shi et Sy. Chao, BIFURCATION OF EASTWARD JETS INDUCED BY MIDOCEAN RIDGES AND DIVERGINGISOBATHS, Tellus. Series A, Dynamic meteorology and oceanography, 47(5), 1995, pp. 1032-1046
A three-dimensional primitive-equation model is employed to investigat
e how a mid-ocean ridge affects an eastward incoming jet overlying iso
baths that diverge eastward. The diverging isobaths contain a major no
rtheastward continental slope and a minor deeper southeastward bottom
slope, both with shallow waters to the north. The southwest-northeast
trending mid-ocean ridge is placed at about 1700 km east of the northe
astward continental slope. In the barotropic regime, the diverging iso
baths force an initially eastward jet to widen and follow f/h contours
after a hydraulic jump. The mid-ocean ridge radiates barotropic Rossb
y waves, further enhancing the lateral widening of the jet. The northe
rn portion of the jet expands northward and forms a western boundary c
urrent along the northeastward continental slope. The bifurcated curre
nt system consists of the northeastward flow and the remnant of the or
iginal eastward current. When the ridge is removed, the jet diverges b
ut does not bifurcate. In the baroclinic regime, continuous meander an
d eddy activities reinforce the meridional spreading of the jet and ca
use greater portion of the jet to diverge northward. Consequently, a s
tronger western boundary current is formed along the northeastward con
tinental slope. As in the barotropic regime, the mid-ocean ridge exert
s its influence upstream by radiating barotropic Rossby waves westward
, further enhancing the jet splitting. Among possible applications, th
e model is particularly relevant to the bifurcation of the Gulf Stream
as it passes by the southern tail of the Grand Banks.