126
A. Bergamasco et al.
In Table 2, zonal (U-component) and méridional (V-component) modelled
transports, integrated along longitude, are given for different latitude values.
Values are computed by adding the net transports (i.e. mean velocities multiplied
by depth) for every grid point, covering about 900 km. Positive U-component values are east-directed transports, while positive V-component values are northdirected ones. Integrated values show a net transport outflowing the RIS along its
edge with a prévalent westward direction. The value of the y-transport component is increasing going equatorward because of the Ross gyre current injection.
The température distribution at 78 °S (Fig. 5a, where blanked areas near the
surface are ice-covered ones), along the RIS edge, shows a dipole warm-cold of
interacting water masses. The cold core reaches -2.1 °C, and is related to isohaline
of 34.65 PSU, while the relatively warm core has a température around -1.5 °C and
salinity of 34.45 PSU. The velocity section presented in Fig. 5b confirms an entering velocity under the shelf for the warm core, and an outgoing one for the cold
one. Particularly, V velocity section présents two cores of water entering the RIS,
while the outgoing one stands in their middle; U velocities are generally westward
directed.
The cold core water is saltier than the warm one; in order to produce such a
water, warm core water entering below the RIS must interact with HSSW which
can be produced during events of strong évaporation associated with cold wind.
Such events could be related to polynya areas that appeared more frequently in
the west area of the Ross Sea during winter. This kind of water can be stored below
the RIS along its western part, constrained by deeper topography.
The T-S field along the west-east transect (again 161-190 °E) at parallel 77 °S
(Fig. 6) confirms the water masses movements: the cold core is quite clear; if compared with Fig. 5a, a portion of it has been able to move to the north, while a part
of it will be later constrained by the sea mount visible at its west, probably mixing
vertically. The signature of the intermediate minimum is lost, while the warm
core, entering the Ross Sea, is still évident, with higher maximum values. Figure 6
reveals another characteristic aspect of the Ross Sea, that is a salinity decreasing
almost linearly going from west to east, and increasingly from surface to bottom.
We can now take into considération some vertical sections of the area below
the RIS edge latitude, which could be, even if preliminary, of relevant interest in
order to gain some useful information about the process simulations under the
RIS itself. For instance, checking the température plot of Fig. 5a against Fig. 7
(representing T-S field along a west-east transect, 161-190 °E, at parallel 78.5 °S),
we can observe that the cold core originated doser to the RIS base (Fig. 7) and
after that sinked to deeper depths (Fig. 5a).
Velocity plots (not presented here) demonstrate a dominant east-directed
(positive values) U velocity in the western and eastern part of the cross. V-component values are mainly directed into the RIS in the western région; still, water
masses with opposite velocities are présent along the section. This activity is also
confirmed by the U-V field along a west-east transect, again 161-190°E, at parallel 79 °S, even if in a reduced way. Under the RIS, a slow cyclonic circulation establishes, probably moving the saltier water doser to the RIS bottom base, where
warm-cold interaction processes take place. The major activity areas may extend
tor about 40-60 km along the RIS. Considering Fig. 8, the warm core signal
A. Bergamasco et al.
In Table 2, zonal (U-component) and méridional (V-component) modelled
transports, integrated along longitude, are given for different latitude values.
Values are computed by adding the net transports (i.e. mean velocities multiplied
by depth) for every grid point, covering about 900 km. Positive U-component values are east-directed transports, while positive V-component values are northdirected ones. Integrated values show a net transport outflowing the RIS along its
edge with a prévalent westward direction. The value of the y-transport component is increasing going equatorward because of the Ross gyre current injection.
The température distribution at 78 °S (Fig. 5a, where blanked areas near the
surface are ice-covered ones), along the RIS edge, shows a dipole warm-cold of
interacting water masses. The cold core reaches -2.1 °C, and is related to isohaline
of 34.65 PSU, while the relatively warm core has a température around -1.5 °C and
salinity of 34.45 PSU. The velocity section presented in Fig. 5b confirms an entering velocity under the shelf for the warm core, and an outgoing one for the cold
one. Particularly, V velocity section présents two cores of water entering the RIS,
while the outgoing one stands in their middle; U velocities are generally westward
directed.
The cold core water is saltier than the warm one; in order to produce such a
water, warm core water entering below the RIS must interact with HSSW which
can be produced during events of strong évaporation associated with cold wind.
Such events could be related to polynya areas that appeared more frequently in
the west area of the Ross Sea during winter. This kind of water can be stored below
the RIS along its western part, constrained by deeper topography.
The T-S field along the west-east transect (again 161-190 °E) at parallel 77 °S
(Fig. 6) confirms the water masses movements: the cold core is quite clear; if compared with Fig. 5a, a portion of it has been able to move to the north, while a part
of it will be later constrained by the sea mount visible at its west, probably mixing
vertically. The signature of the intermediate minimum is lost, while the warm
core, entering the Ross Sea, is still évident, with higher maximum values. Figure 6
reveals another characteristic aspect of the Ross Sea, that is a salinity decreasing
almost linearly going from west to east, and increasingly from surface to bottom.
We can now take into considération some vertical sections of the area below
the RIS edge latitude, which could be, even if preliminary, of relevant interest in
order to gain some useful information about the process simulations under the
RIS itself. For instance, checking the température plot of Fig. 5a against Fig. 7
(representing T-S field along a west-east transect, 161-190 °E, at parallel 78.5 °S),
we can observe that the cold core originated doser to the RIS base (Fig. 7) and
after that sinked to deeper depths (Fig. 5a).
Velocity plots (not presented here) demonstrate a dominant east-directed
(positive values) U velocity in the western and eastern part of the cross. V-component values are mainly directed into the RIS in the western région; still, water
masses with opposite velocities are présent along the section. This activity is also
confirmed by the U-V field along a west-east transect, again 161-190°E, at parallel 79 °S, even if in a reduced way. Under the RIS, a slow cyclonic circulation establishes, probably moving the saltier water doser to the RIS bottom base, where
warm-cold interaction processes take place. The major activity areas may extend
tor about 40-60 km along the RIS. Considering Fig. 8, the warm core signal