Physical Oceanography, Vol. 15, No. 2, 2005
LARGE-SCALE STRUCTURE OF THERMAL FRONTS IN THE EAST PART
OF THE TROPICAL ATLANTIC AND THEIR SEASONAL VARIABILITY
Yu. V. Artamonov and E. A. Skripaleva
UDC 551.46 (269.4)
On the basis of the climatic array of hydrological annual and monthly average data on tempera-
ture and the data of satellite observations of the surface temperature of the ocean, we refine the
annual average structure of the temperature fronts and study their seasonal variability in the east
part of the Tropical Atlantic in the meridional sections made along
10°E. It is shown that the maximum intensity and seasonal variations are typical of the North
Subequatorial and South Tropical Fronts varying with predominant annual period. We revealed
a delay of 2–3 months in the attainment of the maximum intensity of the South Tropical and
South Subequatorial Fronts in the west–east direction. Various mechanisms specifying the sea-
sonal variability of the surface and subsurface North and South Subequatorial Fronts are dis-
cussed. There exists good agreement between the specific features of the seasonal variability of
characteristics of the fronts established according to the hydrological and satellite data.
The last intense investigations of the Tropical Atlantic were carried out in the 1980s and early 1990s. Sig-
nificant advances were attained in the analyses of the thermohaline structure, circulation of water, meridional
heat transfer, and interannual variations of the hydrophysical characteristics in the north part of the region [1–4].
However, these results were almost not discussed from the viewpoint of formation of climatic fronts and, thus,
the basic concepts existing in this field remained practically unchanged since the 1970s and early 1980s [5–7].
An important contribution to the investigation of climatic fronts was made by the works performed on the basis
of the array of hydrological data . The application of this array made it possible to reveal the most intense
areas of large-scale fronts and determine the extreme mean seasonal values of gradients in the temperature, sali-
nity, and density fields [9–12].
A new more comprehensive version of the climatic array appeared in 1994. Parallel with the annual and
seasonal average data, this array also contained the monthly average data . On the basis of this version of the
data array, the annual average structure of large-scale fronts in the central part of the Atlantic Ocean is made
more precise and their relationship with the location of elements of large-scale circulation of waters is estimated
in . It is shown that the North Tropical Front (NTF) is located in the north part of the tropical region in the
zone of of action of the North Equatorial Current. The North Subequatorial Front (NSEF) corresponding to the
North Equatorial Countercurrent (NECC) is located somewhat to the south of the NTF. In the east part of the in-
vestigated region, we observe the formation of the North Branch of the NECC and the corresponding front is
called the North Branch of the NSEF (NB NSEF). Between the NSEF and the Lomonosov Current (LC), we ob-
serve the North Branch of the South Equatorial Current (SEC) and the Front of the North Branch of the SEC
(FNB SEC). To the south of the LC, we detect the Central Branch of the SEC and the South Tropical Front
(STF). The east subthermoclinic current is located under the Central Branch of the SEC. This current corres-
ponds to the South Subequatorial Front (SSEF). To the south of these structures, we observe the South Equator-
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
46–59, March–April, 2005. Original article submitted November 10,
0928-5105/05/1502–0105 © 2005 Plenum Publishing Corporation 105