Temporal Variability of Currents in the Ross Sea (Antarctica)
107
puted respectively as 1.45 x 106 m3 northward and 0.75 x 106 m3 southward; resulting net transport is 0.11 x 106 m3 directed 337°N.
Moving northward to the shelf break, the signature of the core of Ice Shelf
Water disappears at about 77.5 °S, where it supposedly deviates west; this is why
such a cold water is never detected by the sensors of mooring H. Currents and
température and salinity data from mooring H indicate waters leaving the Ross
Shelf to the open océan after having circulated in the western side. Prevailing
directions of currents are north-northeast and southeast with respectively 45 and
38% of daily mean data. Southeastern currents, with lower intensity, are mainly
observed in April and May, while in December and January they are higher and
northward. Daily mean velocities are rather high: more than 25% higher than 10
cm/s, with peaks of more than 35 cm/s. The flow is strongly barotropic: from
empirical orthogonal function (EOF) analysis the first mode reaches 93.8%, while
the second is only 4.4%. Meandering, oscillations and complété anticlockwise
rotations occurring in July and January 1996 can be observed simultaneously at
ail depths (Fig. 3a). Resulting annual mean velocity at ail depths is directed
around 65°N with an intensity of 3-4 cm/s (Table 2).
Table 2. Mean current intensity with standard déviations and maximum; mean velocity
components with standard déviations and resulting module and direction. Velocities are
in centimeters per second; direction in °N. The whole period of measurements was considered for each mooring (A-H)
A
B
C
F
Depth (m)
220 780
220 555
230 425
244
391
579
Mean speed
6.4 6.9
5.0 5.3
9.6
9.2
9.7 10.0
9.9
o
3.3 3.1
3.1 2.4
4.1
3.5
5.5
5.7
6.3
Max speed
22.2 18.7
15.6 15.5
20.7 21.8
26.8 27.1 31.7
Vx
0.6 1.5
0.4 2.8
-2.3 -5.9
-3.5 -2.2
2.0
ox
6.0 5.3
4.1 3.2
4.9. 4.2
8.0
8.5
7.4
Vy
-0.5 -0.7
-0.6 0.1
6.0
5.8
2.5
2.0
4.6
oy
3.6 5.2
4.4 4.1
4.2
3.1
6.6
7.2
7.7
Module
0.7 1.3
0.6 2.3
8.0
8.4
4.3
3.0
5.0
Direction
129 127
147 89
343 316
306
312 337
D
H
Depth (m)
55
140
402 748
885
283 450
503 597
Mean speed
14.1
9.3
7.1
6.7
8.0
7.9 7.7
6.7 6.5
o
9.0
5.4
4.4 4.9
5.7
4.9 4.7
4.4 3.9
Max speed
48.2 27.5 24.7 24.0
26.3
28.2 26.6 26.5 22.9
Vx
-0.8 -1.1
0.6 2.6
4.9
3.2 3.8
2.7 2.7
ox
9.6
7.2
5.7 5.4
5.8
5.2 5.0
4.1
3.9
Vy
7.7
3.0
2.1
0.9
0.4
1.7 1.5
1.5 0.9
oy
11.3
7.3
5.7 5.8
6.2
6.8 6.3
6.2 5.9
Module
7.8
3.2
2.1 42.8
4.9
3.6 4.1
3.1
2.9
Direction
354
340
15
71
86
62
69
61
72
107
puted respectively as 1.45 x 106 m3 northward and 0.75 x 106 m3 southward; resulting net transport is 0.11 x 106 m3 directed 337°N.
Moving northward to the shelf break, the signature of the core of Ice Shelf
Water disappears at about 77.5 °S, where it supposedly deviates west; this is why
such a cold water is never detected by the sensors of mooring H. Currents and
température and salinity data from mooring H indicate waters leaving the Ross
Shelf to the open océan after having circulated in the western side. Prevailing
directions of currents are north-northeast and southeast with respectively 45 and
38% of daily mean data. Southeastern currents, with lower intensity, are mainly
observed in April and May, while in December and January they are higher and
northward. Daily mean velocities are rather high: more than 25% higher than 10
cm/s, with peaks of more than 35 cm/s. The flow is strongly barotropic: from
empirical orthogonal function (EOF) analysis the first mode reaches 93.8%, while
the second is only 4.4%. Meandering, oscillations and complété anticlockwise
rotations occurring in July and January 1996 can be observed simultaneously at
ail depths (Fig. 3a). Resulting annual mean velocity at ail depths is directed
around 65°N with an intensity of 3-4 cm/s (Table 2).
Table 2. Mean current intensity with standard déviations and maximum; mean velocity
components with standard déviations and resulting module and direction. Velocities are
in centimeters per second; direction in °N. The whole period of measurements was considered for each mooring (A-H)
A
B
C
F
Depth (m)
220 780
220 555
230 425
244
391
579
Mean speed
6.4 6.9
5.0 5.3
9.6
9.2
9.7 10.0
9.9
o
3.3 3.1
3.1 2.4
4.1
3.5
5.5
5.7
6.3
Max speed
22.2 18.7
15.6 15.5
20.7 21.8
26.8 27.1 31.7
Vx
0.6 1.5
0.4 2.8
-2.3 -5.9
-3.5 -2.2
2.0
ox
6.0 5.3
4.1 3.2
4.9. 4.2
8.0
8.5
7.4
Vy
-0.5 -0.7
-0.6 0.1
6.0
5.8
2.5
2.0
4.6
oy
3.6 5.2
4.4 4.1
4.2
3.1
6.6
7.2
7.7
Module
0.7 1.3
0.6 2.3
8.0
8.4
4.3
3.0
5.0
Direction
129 127
147 89
343 316
306
312 337
D
H
Depth (m)
55
140
402 748
885
283 450
503 597
Mean speed
14.1
9.3
7.1
6.7
8.0
7.9 7.7
6.7 6.5
o
9.0
5.4
4.4 4.9
5.7
4.9 4.7
4.4 3.9
Max speed
48.2 27.5 24.7 24.0
26.3
28.2 26.6 26.5 22.9
Vx
-0.8 -1.1
0.6 2.6
4.9
3.2 3.8
2.7 2.7
ox
9.6
7.2
5.7 5.4
5.8
5.2 5.0
4.1
3.9
Vy
7.7
3.0
2.1
0.9
0.4
1.7 1.5
1.5 0.9
oy
11.3
7.3
5.7 5.8
6.2
6.8 6.3
6.2 5.9
Module
7.8
3.2
2.1 42.8
4.9
3.6 4.1
3.1
2.9
Direction
354
340
15
71
86
62
69
61
72