Physical Oceanography, Vol. 16, No. 6, 2006
HORIZONTAL STRUCTURE OF THE TEMPERATURE FIELD OF THE UPPER
LAYER IN THE NORTHWEST PART OF THE TROPICAL ATLANTIC
V. A. Blinkov
By using the data of observations over the spatial variability of the temperature field in the north-
west part of the Tropical Atlantic carried out in a test range
in size with a hori-
x ≈ 2
and a vertical resolution
z ≈ 0.5
we recorded quasiperiodic fluc-
tuations of temperature with semidiurnal period in the subsurface layer. The internal baroclinic
waves with the same period generated, most likely, on the northeast shelf of South America and
propagating to the northeast are detected in the seasonal thermocline. The vertical fine structure
of the temperature field has different intensities in the test range. The maximum levels of disper-
sions of temperature fluctuations are recorded on the boundary of the North Equatorial Counter-
current and the North Equatorial Current.
The formation of three-dimensional temperature inhomogeneities of different sizes in the upper layer of the
ocean is an important factor affecting the processes of interaction between the atmosphere and the ocean, the
process of propagation of the particulate substance and pollutants, and the concentration of phyto- and zooplank-
To study the processes of formation of the three-dimensional structures of fields in the upper layer of the
ocean and obtain reliable statistical estimates of the horizontal variability of the temperature field, it is necessary
to have the data of in-situ observations carried out with high spatial resolution in sufficiently large test ranges.
In the present work, we describe some results of observations of the horizontal inhomogeneities of the tempera-
ture field performed in the upper
layer of the northwest part of the Tropical Atlantic with a higher spatial
resolution than the resolution usually realized in the course of standard CTD-surveys with the help of hydrologi-
The structure of thermohaline fields in the investigated region is formed as a result of the interaction of
different water masses in the system of main currents of the Atlantic Ocean including the North Equatorial Cur-
rent (NEC), the South Equatorial Current (SEC), the North Brazilian Current, and the North Equatorial Counter-
current (NECC) . The interaction of water masses is accompanied by the formation of a pronounced spatial
variability of the temperature and salinity fields and the generation of intense fine vertical structure caused by
double diffusion  and intrusion processes . The diurnal variations of temperature with amplitudes of
are typical of the surface layer in this region.
The extreme values are observed at
local solar time . The results of the analysis of the data of autonomous buoy stations (ABS) show that the se-
midiurnal oscillations connected with the main lunar component of tidal waves (with a period of
pronounced in the analyzed region. The maximum energy density of these motions is attained in the upper
mixed layer (UML) and in the layer of the jump of density . The investigations of internal waves carried out
according to a special procedure  by using ABS demonstrate that, in the syzygial phase of the tide, one may
observe the formation of solitary waves with amplitudes of up to
following each other with tidal semi-
diurnal intervals. In the quadrature, the height of internal tide was equal to
and the solitary waves were
not detected .
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
44–52, November–December, 2006. Original article submitted April 6,
2005; revision submitted June 13, 2005
350 0928-5105/06/1606–0350 © 2006 Springer Science+Business Media, Inc.