Physical Oceanography, Vol. 17, No. 1, 2007
MERIDIONAL HEAT TRANSPORT IN THE NORTH ATLANTIC AND THE TRENDS
OF ITS VARIATIONS IN THE SECOND HALF OF THE 20TH CENTURY
A. B. Polonskii and S. B. Krasheninnikova
Dedicated to the 75th birthday of N. A. Timofeev,
Honored Scientist of the Ukraine,
Doctor of Geographical Sciences
The meridional heat transport in the ocean is computed according to the data of zonal sections of
the World Ocean Circulation Experiment made in the North Atlantic in 1992–1998. We perform
the generalized analysis of the estimates of meridional heat transport obtained by different au-
thors by direct methods on the basis of the data of sections made between
second half of the last century.
The meridional heat transport averaged over the entire period of
observations attains its maximum
in the Subtropical Atlantic.
heat transport is characterized by fairly intense seasonal variability.
Its maximum (about
is observed in the Subtropical Atlantic at the end of summer and its minimum (about 0.8
attained at the end of winter.
A significant trend toward the intensification of meridional heat
transport is revealed near
in 1959–1993 (from
This is an indication of
the intensification of meridional oceanic circulation in the North Atlantic.
The heat transport by oceanic currents is one of the main mechanisms of the influence of the ocean on the
formation of the global climatic system. The meridional heat transport (MHT) is especially important at the
tropical and subtropical latitudes since the thermal contrasts between the high and low latitudes in the ocean–at-
mosphere system decrease just as a result of MHT and the principal part of the total transport at these latitudes
belongs to the oceanic MHT. The Atlantic Ocean plays an especial role in the formation of the global MHT. It
is characterized by the presence of a quasistationary heat transport to the north [1–8] caused by a global thermo-
haline circulation cell formed as a result of convection of deep cold waters at the sites of their formation in the
North Atlantic and the compensating transport of relatively warm waters of the thermocline to the north [9, 10].
The variations of the intensity of meridional circulation in the Atlantic Ocean control, to a significant extent, the
low-frequency variations of the ocean–atmosphere system. Hence, the problem of correct simulation of the glo-
bal climate and its variations requires the exact knowledge of the mean values of MHT in the ocean and the
trends of their variations in the observed process of global warming. Unfortunately, the available data on the
MHT in the ocean are fairly contradictory. They are based on the following two basic procedures of evaluation
of the MHT:
— direct oceanographic measurements ;
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
45–58, January–February, 2007. Original article submitted September 5,
2005; revision submitted October 7, 2005.
0928-5105/07/1701–0041 © 2007 Springer Science+Business Media, Inc. 41