60
A. Simone et al.
ing and descending) were calculated at each cross-over point. Then, they were
interpolated linearly to common time (every 5 days) and used to dérivé the zonal
(u') and méridional (u') components of the geostrophic velocity fluctuations:
u ------ -——
2costp
V = ---- 2--- ±2sin(p
where Vd are the components of the geostrophic velocity perpendicular to the ascending and descending track, respectively.
The covariances of the velocity fluctuations, and are then
computed from the 2-year time sériés of u’ and v’ velocity components. The
results are displayed in Fig. 6. It is important to underline that Johnson et al. [13]
estimated that the decorrelation times from u' and v' are 31 and 14 days, respectively. This gives high reliability to results from analysis of T/P crossover, being
the maximum delay between the two passes at the crossover less than 10 days.
The patterns of , and (see Fig. 6) show a fair geographical
cohérence with scales of hundreds of kilométrés. In several areas, mostly at the
lower latitudes,
exceeds as already noticed [10]. This means that
the mesoscale eddies are strongly anisotropic. The interaction of the mean current with the bottom topography produces a complex pattern of. Relatively
high values of are alearly visible in the area of the Pacific-Antarctic Ridge
and near the Kerguelen Plateau.
The magnitude and the direction of the eddy variability are represented in
Fig. 7 by the variance ellipses. The direction of the axis of principal variability,
measured counterclockwise from east, is:
tand =
on -
where j is the variance along the major axis and is given by
a.. = — (++ J (-)2+4 2
2
while the variance along the minor axis is
u22 = (<«V>2+2) - un.
In the background of Fig. 7 the bottom topography with the main ridges and
shallow plateaus is shown using a gray scale.
An anisotropy flow is represented by elongated ellipses, with the principal
direction of the velocity variance aligned with the direction of the major axis;
ellipses with a major axis oriented toward the northeast quadrant hâve a positive
, while ellipses with a major axis oriented toward the southeast quadrant
hâve a négative.
In Fig. 7 distinct anisotropic variability is most évident in the high eddy
régions of the Agulhas Retroflection and Southwest of the Atlantic région.
A. Simone et al.
ing and descending) were calculated at each cross-over point. Then, they were
interpolated linearly to common time (every 5 days) and used to dérivé the zonal
(u') and méridional (u') components of the geostrophic velocity fluctuations:
u ------ -——
2costp
V = ---- 2--- ±2sin(p
where Vd are the components of the geostrophic velocity perpendicular to the ascending and descending track, respectively.
The covariances of the velocity fluctuations
computed from the 2-year time sériés of u’ and v’ velocity components. The
results are displayed in Fig. 6. It is important to underline that Johnson et al. [13]
estimated that the decorrelation times from u' and v' are 31 and 14 days, respectively. This gives high reliability to results from analysis of T/P crossover, being
the maximum delay between the two passes at the crossover less than 10 days.
The patterns of
cohérence with scales of hundreds of kilométrés. In several areas, mostly at the
lower latitudes,
exceeds
the mesoscale eddies are strongly anisotropic. The interaction of the mean current with the bottom topography produces a complex pattern of
high values of
and near the Kerguelen Plateau.
The magnitude and the direction of the eddy variability are represented in
Fig. 7 by the variance ellipses. The direction of the axis of principal variability,
measured counterclockwise from east, is:
tand =
on -
where j is the variance along the major axis and is given by
a.. = — (
2
while the variance along the minor axis is
u22 = (<«V>2+
In the background of Fig. 7 the bottom topography with the main ridges and
shallow plateaus is shown using a gray scale.
An anisotropy flow is represented by elongated ellipses, with the principal
direction of the velocity variance aligned with the direction of the major axis;
ellipses with a major axis oriented toward the northeast quadrant hâve a positive
hâve a négative
In Fig. 7 distinct anisotropic variability is most évident in the high eddy
régions of the Agulhas Retroflection and Southwest of the Atlantic région.