Physical Oceanography, Vol.
6, March, 2011 (Ukrainian Original No.
6, November–December, 2010)
ANALYSIS OF OBSERVATIONS AND METHODS FOR CALCULATING
HYDROPHYSICAL FIELDS IN THE OCEAN
SPACE-AND-TIME VARIABILITY OF THE MERIDIONAL HEAT TRANSPORT
IN THE NORTH ATLANTIC
A. B. Polonsky
and S. B. Krasheninnikova
We analyze the space-and-time variability of the meridional heat transport in the North Atlantic. The
contribution of various mechanisms to the integral meridional heat transport (MHT) is estimated. The
key role played by the drift transport of the Tropical Atlantic in the formation of the meridional oceanic
heat transport is confirmed. On the basis of the general analysis of estimations obtained by various
authors according to the data accumulated for 1870–2008 and the results of numerical analyses based on
the data of NCEP/NCAR reanalysis, we show that the long-term average meridional drift heat (mass)
transport attains its maximum values equal to (1.6 ± 0.1) PW [(17.4 ± 1.5) Sv] in the vicinity of 12.5°N
in the Tropical Atlantic. The contribution of the heat transport caused by the horizontal Sverdrup circu-
lation to the integral meridional heat transport is maximum in the vicinity of 30º N. On the average, it is
equal to ~
40%. In the Subtropical Atlantic, the meridional heat transport varies with a period of ~
yr. The minimum value of the integral meridional heat transport was attained in the mid-1960s and
its maximum value was at attained at the beginning of the 1990s. The location of the center of Azores
pressure maximum makes it possible to conclude that the intensification of the total meridional heat
transport in the Subtropical Atlantic on these time scales is accompanied by the displacement of the cen-
ter of the North Subtropical anticyclonic gyre in the southwest direction.
It is known that the ocean plays a significant role in the process of formation and in the variations of global
climate. As one of the main mechanisms of action of the ocean on the climatic system, we can mention the me-
ridional heat transport. Indeed, the meridional heat transport leads to the redistribution of heat in the ocean and
smoothening of the thermal contrasts between high and low latitudes. It is also responsible for the major part of
the total heat transport in the ocean–atmosphere system at the tropical and subtropical latitudes. Moreover, the
meridional heat transport is one of the main mechanisms governing the climatic variations on the decadal and
centennial scales. The results of investigations of the processes of advective and diffusive heat transport in the
North Atlantic are presented in numerous works (see, e.g., [1–3] and references therein).
Unfortunately, the reliable detection of low-frequency variations of the oceanological characteristics (in-
cluding the meridional heat transport) with typical periods varying from ten years till several decades is a diffi-
cult problem even now due to the limited amount of the available data of observations and high levels of noise
Marine Hydrophysical Institute, Ukrainian National Academy of Sciences, Sevastopol, Ukraine; e-mail: email@example.com.
Marine Hydrophysical Institute, Ukrainian National Academy of Sciences, Sevastopol, Ukraine; e-mail: firstname.lastname@example.org.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
24–41, November–December, 2010. Original article submitted August 19,
2009; revision submitted November 2, 2009.
0928–5105/11/2006–0419 © 2011 Springer Science+Business Media, Inc. 419