Conclusions
We studied bottom water flows between the Argentine and Brazil basins on the
basis of a three-dimensional regional model with high spatial resolution in the
bottom layers and our field CTD and LADCP measurements in this region. From
this point of view, we considered two main passages for AABW in this region: the
deep and narrow Vema Channel and the relatively shallow and wide Santos Plateau.
The main results of this work are as follows.
1. A steady northward bottom water flow is observed in the southern part of the
Vema Channel north of 33° S. According to our measurements, the velocities
were 10–15 cm/s at the beginning of the channel (32° 17′ S) and 25–30 cm/s in
its middle part (31° 12′ S). The increase in the bottom temperature along the
channel was of the order of 0.01°/100 km. The core of cold waters is displaced
to the east at any section across the channel; the difference between the bottom
temperatures near the eastern and western walls of the channel was 0.02 °C.
2. Numerical modeling revealed two branches of the current in the middle part of
the channel. The major jet was located in the deepest part of the channel; the
additional jet was found at depths of 4300–4400 on the southeastern slope. The
lengths of the jets were 200 km and the maximum distance between them was
50 km. After the outflow from the Vema Channel, the bottom current turns to
the north and propagates along the western boundary of the Brazil Basin.
3. A strong unsteady current was found in the southwestern part of the Santos
Plateau. The bottom velocities here vary from 30 cm/s to the south up to 20 cm/s
to the north. According to our CTD-measurements, the corresponding difference
in the bottom temperatures was 0.31 °C. At 32°–32° 30′ S, the current turns to
the east and propagates along the northern slope of the Argentine Basin.
Acknowledgments The work has been supported by the Russian Foundation for Basic Research
grants 15-05-07539, 15-01-03942, 17-08-00085 (field studies); Russian Science Foundation
project 16-17-10149 (data analysis).
References
1. Anisimov, M. V., & Diansky, N. A. (2008). Physical mechanism of the westward drift of the
frontal current rings in the ocean. Oceanology, 48(3), 321–327.
2. Antonov, J. I., Seidov, D., Boyer, T. P., et al. (2010). World Ocean Atlas 2009 Vol. 2:
Salinity. In S. Levitus (Ed.), NOAA Atlas NESDIS 69 (p. 184). Washington, D.C.: U.S.
Government Printing Office.
3. Danabasoglu, G., Yeager, S. G., Bailey, D., et al. (2014). North Atlantic simulations in
coordinated ocean-ice reference experiments phase II (CORE-II) Part I: Mean states. Ocean
Modelling, 73, 76–107.
4. Diansky, N. A., Bagno, A. V., & Zalesny, V. B. (2002). Sigma model of global ocean
circulation and its sensitivity to variations in wind stress. Izvestiya Atmospheric and Oceanic
Physics, 38(4), 537–556.
484
D. I. Frey et al.
We studied bottom water flows between the Argentine and Brazil basins on the
basis of a three-dimensional regional model with high spatial resolution in the
bottom layers and our field CTD and LADCP measurements in this region. From
this point of view, we considered two main passages for AABW in this region: the
deep and narrow Vema Channel and the relatively shallow and wide Santos Plateau.
The main results of this work are as follows.
1. A steady northward bottom water flow is observed in the southern part of the
Vema Channel north of 33° S. According to our measurements, the velocities
were 10–15 cm/s at the beginning of the channel (32° 17′ S) and 25–30 cm/s in
its middle part (31° 12′ S). The increase in the bottom temperature along the
channel was of the order of 0.01°/100 km. The core of cold waters is displaced
to the east at any section across the channel; the difference between the bottom
temperatures near the eastern and western walls of the channel was 0.02 °C.
2. Numerical modeling revealed two branches of the current in the middle part of
the channel. The major jet was located in the deepest part of the channel; the
additional jet was found at depths of 4300–4400 on the southeastern slope. The
lengths of the jets were 200 km and the maximum distance between them was
50 km. After the outflow from the Vema Channel, the bottom current turns to
the north and propagates along the western boundary of the Brazil Basin.
3. A strong unsteady current was found in the southwestern part of the Santos
Plateau. The bottom velocities here vary from 30 cm/s to the south up to 20 cm/s
to the north. According to our CTD-measurements, the corresponding difference
in the bottom temperatures was 0.31 °C. At 32°–32° 30′ S, the current turns to
the east and propagates along the northern slope of the Argentine Basin.
Acknowledgments The work has been supported by the Russian Foundation for Basic Research
grants 15-05-07539, 15-01-03942, 17-08-00085 (field studies); Russian Science Foundation
project 16-17-10149 (data analysis).
References
1. Anisimov, M. V., & Diansky, N. A. (2008). Physical mechanism of the westward drift of the
frontal current rings in the ocean. Oceanology, 48(3), 321–327.
2. Antonov, J. I., Seidov, D., Boyer, T. P., et al. (2010). World Ocean Atlas 2009 Vol. 2:
Salinity. In S. Levitus (Ed.), NOAA Atlas NESDIS 69 (p. 184). Washington, D.C.: U.S.
Government Printing Office.
3. Danabasoglu, G., Yeager, S. G., Bailey, D., et al. (2014). North Atlantic simulations in
coordinated ocean-ice reference experiments phase II (CORE-II) Part I: Mean states. Ocean
Modelling, 73, 76–107.
4. Diansky, N. A., Bagno, A. V., & Zalesny, V. B. (2002). Sigma model of global ocean
circulation and its sensitivity to variations in wind stress. Izvestiya Atmospheric and Oceanic
Physics, 38(4), 537–556.
484
D. I. Frey et al.