Physical Oceanography, Vol.
GEOSTROPHIC CIRCULATION OF WATERS IN THE SOUTH ATLANTIC OCEAN
AND ITS SEASONAL VARIABILITY
Yu. V. Artamonov, N. P. Bulgakov, and P. D. Lomakin
Based on an analysis of the monthly average diagrams of dynamic topography, we reveal some
specific features of the geostrophic circulation of waters in the South Atlantic Ocean. We
present an improved picture of the structure and annual variability of the climatic large-scale cir-
culations. They are compared with similar climatic cells of the large-scale circulation of waters
in the north part of the ocean. Quantitative estimates of the characteristics of seasonal oscilla-
tions of the field of dynamic heights are obtained.
In the last decades, constantly increasing practical needs (connected with the development of new regions
of fishery outside the exclusive economic zones and the solution of various climatic, ecological, and navigation
problems) have significantly intensified investigations of the South-Atlantic region. In addition to the well-
known classical works [1–3], numerous new works dealing with the structure and dynamics of waters in this re-
gion of the Atlantic were published [4–8]. Despite the fact that some parts of the South Atlantic are relatively
well described in the oceanographic literature, the system of currents of the south subtropical anticyclonic circu-
lation has not been adequately studied. This makes our understanding of the relationships between its compo-
nents and interaction with the other large-scale circulation systems fairly incomplete. The large-scale oceano-
graphic investigations carried out in recent years in the water area of the South Atlantic according to the
international climatic programs have significantly increased the database of observations, which en-
ables one to study various problems connected with the large-scale dynamics of waters in this region and its sea-
In the present work, by using the contemporary database of oceanographic investigations, we try to im-
prove our understanding of the structure of large-scale circulation of waters in the South Atlantic and study its
annual variability. It is known that the correlation between the circulations and structures of waters to the north
and south of the equator is quite close. Therefore, we performed computations for the water area of the Atlantic
Ocean from the middle latitudes of the Northern Hemisphere to the coast of Antarctica.
As initial data, we use the database of monthly average values of temperature and salinity at the nodes of a
one-degree grid . For each calendar month of a year, the maps of the dynamic topography of the sea surface
are plotted from a reference surface of
m. For the sake of convenience, in these maps, we mark typical
isodynamic lines most clearly reflecting the specific features of dynamic topography and trace their annual vari-
ability. In Fig.
1, these isodynamic lines are displayed as heavy lines and the internal regions of large-scale
circulations are shaded.
Analysis of the maps of dynamic topography shows that there are three large-scale climatic circulations
well visible in the South Atlantic for the whole year, namely, the south subtropical anticyclonic and south tropi-
cal cyclonic circulations located in the central and tropical regions of the South Atlantic and the Weddell Sea cy-
clonic circulation located in the far-south part of the investigated region.
A powerful system of geostrophic currents directed eastward is located, roughly speaking, between 40 and
60°S. The northern part of this system is represented by the South Atlantic Current. The branches of the Ant-
arctic Circumpolar Current are located to the south.
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol. Translated from Morskoi Gidrofizicheskii Zhurnal,
43–50, May–June, 2002. Original article submitted June 26, 2000; revision submitted March 30, 2001.
156 0928-5105/02/1203–0156 $27.00 © 2002 Plenum Publishing Corporation