Altimeter Data Analysis of the Antarctic
Circumpolar Current
A. Simone1, S. Zoffoli1, D. Iudicone1, R. Santoleri1 and S. Marullo2
^NR, Istituto di Fisica dell’Atmosfera, 00144 Rome, Italy
2ENEA, Casaccia S. Maria di Galeria, 00060 Rome, Italy
Abstract
The First two years of TOPEX/POSEIDON altimeter measurements of the
Southern Océan, between 30° S and 65° S were analyzed in order two study the
mesoscale characteristics of the basin. Objective maps of sea level anomalies were
computed for each cycle, showing synoptic view of the mesoscale activity of the
study area. These maps underlined a population of mesoscale eddies, with a typical diameter of 100 -f 200 Km in the sector 10° -f 50° E and 30° -e- 60° W, possibly
shed from the meanders of the Antarctic Circumpolar Current. The rings seem to
move southward confined to a rather narrow corridor (about 400Km). Sea level
variability maps were computed to characterize the mesoscale activity in the
study area. The highest values of more 25 cm are found between 10° -f 60° E and
near 50° W at a latitude of 40° -f 50° S. A high variability area extends to at least
60° -f 65° S. The TOPEX/POSEIDON cross-over data were used to résolve both
magnitude and direction of residual geostrophic velocities. The time sériés are
then used to détermine surface eddy statistics in the Southern Océan, hence the
spatial distribution in the surface Reynolds stresses (u’2, v’2, u’v’). According with
the information available so far, we found that the complex spatial distribution of
surface eddy momentum flux is strongly influenced by bottom topography and
the position of the mean current.
1 Introduction
Earth-observing satellite is providing a significant quantity of high quality synoptic data for the investigation of the océanographie phenomena on spatial and
temporal scales unattainable with in situ measurements. Satellite altimeter provides a direct measurement of the sea surface slope associated with the
geostrophic current variability since the component of the absolute slope, due to
geoid and mean geostrophic current contribution, is subtracted. Altimeter data
hâve already proved to be able to résolve sea surface variability in régions corresponding to the major western boundary currents (the Gulf Stream, Kuroshio,
Malvinas and Agulhas) and the Antarctic Circumpolar Current.
The launch of TOPEX/POSEIDON (T/P in the following) satellite ushered in a
new era in satellite oceanography by greatly improving the accuracy of the altimeter measurements for each source of errors. The orbits for T/P are estimated to
Circumpolar Current
A. Simone1, S. Zoffoli1, D. Iudicone1, R. Santoleri1 and S. Marullo2
^NR, Istituto di Fisica dell’Atmosfera, 00144 Rome, Italy
2ENEA, Casaccia S. Maria di Galeria, 00060 Rome, Italy
Abstract
The First two years of TOPEX/POSEIDON altimeter measurements of the
Southern Océan, between 30° S and 65° S were analyzed in order two study the
mesoscale characteristics of the basin. Objective maps of sea level anomalies were
computed for each cycle, showing synoptic view of the mesoscale activity of the
study area. These maps underlined a population of mesoscale eddies, with a typical diameter of 100 -f 200 Km in the sector 10° -f 50° E and 30° -e- 60° W, possibly
shed from the meanders of the Antarctic Circumpolar Current. The rings seem to
move southward confined to a rather narrow corridor (about 400Km). Sea level
variability maps were computed to characterize the mesoscale activity in the
study area. The highest values of more 25 cm are found between 10° -f 60° E and
near 50° W at a latitude of 40° -f 50° S. A high variability area extends to at least
60° -f 65° S. The TOPEX/POSEIDON cross-over data were used to résolve both
magnitude and direction of residual geostrophic velocities. The time sériés are
then used to détermine surface eddy statistics in the Southern Océan, hence the
spatial distribution in the surface Reynolds stresses (u’2, v’2, u’v’). According with
the information available so far, we found that the complex spatial distribution of
surface eddy momentum flux is strongly influenced by bottom topography and
the position of the mean current.
1 Introduction
Earth-observing satellite is providing a significant quantity of high quality synoptic data for the investigation of the océanographie phenomena on spatial and
temporal scales unattainable with in situ measurements. Satellite altimeter provides a direct measurement of the sea surface slope associated with the
geostrophic current variability since the component of the absolute slope, due to
geoid and mean geostrophic current contribution, is subtracted. Altimeter data
hâve already proved to be able to résolve sea surface variability in régions corresponding to the major western boundary currents (the Gulf Stream, Kuroshio,
Malvinas and Agulhas) and the Antarctic Circumpolar Current.
The launch of TOPEX/POSEIDON (T/P in the following) satellite ushered in a
new era in satellite oceanography by greatly improving the accuracy of the altimeter measurements for each source of errors. The orbits for T/P are estimated to