64
A. Simone et al.
The SLV maps show high variability values at the boundary of the three main
fronts. The highest values of more 25 cm are found between 10-60°E and near
50°W at a latitude of 40-50°S. A high variability area extends to at least 60-65°S.
The 2-yearly SLV maps show very similar patterns (Figs. 4 and 5). These maps are
also in good agreement with previous analysis of Geosat satellite altimeter. This
indicates that interannual variability does not affect the ACC eddy field. This
could be due either to a lack of variability of the forcing (mainly the wind stress)
or to a not negligible rôle of the topographie steering of the current.
Then we adopted a technique [10] for resolving both magnitude and direction
of residual surface geostrophic velocities at T/P altimeter crossover points on the
basis of the 2-year time sériés with a temporal resolution of 10 days and horizontal resolution of about 200 km (spacing between tracks). 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 to
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.
References
1. Tapley B.D, Ries JC, Davis GW, Eanes RJ, Schutz BE, Shum CK, Watkins MM, Marshall JA, Nerem
RS, Putney BH, Klosko SM, Luthcke SB, Pavlis D, Williamson RG, Zelensky NP (1994) Précision
orbit détermination for TOPEX/POSEIDON. J Geophys Res 99(C12):24383-24404
2. Nowlin WD Jr, Klinck JM(1986) The physics of the Antarctic Circumpolar Current. Rev Geophys
24:469-491
3. Nowlin WD Jr, Clifford M (1982) The Kinematic and thermohaline zonation of the Antarctic
Circumpolar Current at Drake Passage. J Mar Res 405:481-507
4. Munk WH, Palmen E (1951) Note on the dynamics of the Antarctic Circumpolar Current. Tellus
3:53-55
5. Hughes CW, Killworth PD (1995) Effects of bottom topography in the large-scale circulation of
the Southern Océan. JPO 25:2485-2497
6. Wells NC, de Cuevas BA (1995) Depth-integrated vorticity budget of the Southern Océan from a
general circulation model. JPO 25:2569-2582
7. McWilliams JC, Holand WR, Chow JS (1978) A description of numerical Antarctic Circumpolar
Current, Dyn. Atmos Océans 2:213-291
8. Stevens DP, Ivchenko VD (1996) The zonal momentum balance in a realistic eddy resolving general circulation model of the Southern Océan. Quart J Roy Meteor Soc, submitted
9. Ivchenko VO, Kelvin JR, Davin PS (1996) The dynamics of the ACC. JPO 26:753-774
10. Morrow R, Coleman R, Church J, Chelton D (1994) Surface eddy momentum flux and velocity
variance in the Southern océan from Geosat altimetry. J Phys Oceanogr 24:2050-2071
11. Chelton DB, Schlax MG, Witter DL, Richman JC (1990) Geosat altimeter observation of the surface circulation of the Southern Océan. J Geophys Res 95(C10):877-904
12. Morrow R, Church J, Coleman R, Chelton D, White N (1992) Eddy momentum flux and its contribution to the Southern Océan momentum balance. Nature 357:482-484
13. Johnson TJ, Stewart RH, Shum CK, Tapley BD (1992) Distribution of Reynolds stress carried by
mesoscale variability in the Antartic Circumpolar Current, Geophys Res Lett 19:1201-1204
14. Gille ST (1994) Mean surface height of the Antarctic Circumpolar Current. J Geophys Res 99
(C9):255-273
15. Park Y, Gamberoni L (1995) Large-scale circulation and its variability in the south Indian Océan
from TOPEX/POSEIDON altimetry. J Geophys Res 100(C12):911-929
A. Simone et al.
The SLV maps show high variability values at the boundary of the three main
fronts. The highest values of more 25 cm are found between 10-60°E and near
50°W at a latitude of 40-50°S. A high variability area extends to at least 60-65°S.
The 2-yearly SLV maps show very similar patterns (Figs. 4 and 5). These maps are
also in good agreement with previous analysis of Geosat satellite altimeter. This
indicates that interannual variability does not affect the ACC eddy field. This
could be due either to a lack of variability of the forcing (mainly the wind stress)
or to a not negligible rôle of the topographie steering of the current.
Then we adopted a technique [10] for resolving both magnitude and direction
of residual surface geostrophic velocities at T/P altimeter crossover points on the
basis of the 2-year time sériés with a temporal resolution of 10 days and horizontal resolution of about 200 km (spacing between tracks). 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 to
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.
References
1. Tapley B.D, Ries JC, Davis GW, Eanes RJ, Schutz BE, Shum CK, Watkins MM, Marshall JA, Nerem
RS, Putney BH, Klosko SM, Luthcke SB, Pavlis D, Williamson RG, Zelensky NP (1994) Précision
orbit détermination for TOPEX/POSEIDON. J Geophys Res 99(C12):24383-24404
2. Nowlin WD Jr, Klinck JM(1986) The physics of the Antarctic Circumpolar Current. Rev Geophys
24:469-491
3. Nowlin WD Jr, Clifford M (1982) The Kinematic and thermohaline zonation of the Antarctic
Circumpolar Current at Drake Passage. J Mar Res 405:481-507
4. Munk WH, Palmen E (1951) Note on the dynamics of the Antarctic Circumpolar Current. Tellus
3:53-55
5. Hughes CW, Killworth PD (1995) Effects of bottom topography in the large-scale circulation of
the Southern Océan. JPO 25:2485-2497
6. Wells NC, de Cuevas BA (1995) Depth-integrated vorticity budget of the Southern Océan from a
general circulation model. JPO 25:2569-2582
7. McWilliams JC, Holand WR, Chow JS (1978) A description of numerical Antarctic Circumpolar
Current, Dyn. Atmos Océans 2:213-291
8. Stevens DP, Ivchenko VD (1996) The zonal momentum balance in a realistic eddy resolving general circulation model of the Southern Océan. Quart J Roy Meteor Soc, submitted
9. Ivchenko VO, Kelvin JR, Davin PS (1996) The dynamics of the ACC. JPO 26:753-774
10. Morrow R, Coleman R, Church J, Chelton D (1994) Surface eddy momentum flux and velocity
variance in the Southern océan from Geosat altimetry. J Phys Oceanogr 24:2050-2071
11. Chelton DB, Schlax MG, Witter DL, Richman JC (1990) Geosat altimeter observation of the surface circulation of the Southern Océan. J Geophys Res 95(C10):877-904
12. Morrow R, Church J, Coleman R, Chelton D, White N (1992) Eddy momentum flux and its contribution to the Southern Océan momentum balance. Nature 357:482-484
13. Johnson TJ, Stewart RH, Shum CK, Tapley BD (1992) Distribution of Reynolds stress carried by
mesoscale variability in the Antartic Circumpolar Current, Geophys Res Lett 19:1201-1204
14. Gille ST (1994) Mean surface height of the Antarctic Circumpolar Current. J Geophys Res 99
(C9):255-273
15. Park Y, Gamberoni L (1995) Large-scale circulation and its variability in the south Indian Océan
from TOPEX/POSEIDON altimetry. J Geophys Res 100(C12):911-929