NOAA/AOML XBT Network - Meridional Heat Transport

The Meridional Overturning Circulation (MOC) is a global circulation cell wherein surface waters in the high latitudes are cooled, thereby becoming denser; this dense water sinks and flows towards the equatorial regions. In tropical and subtropical regions around the world these waters eventually mix with other waters, becoming less dense, and they return to the sea surface to ultimately flow towards the higher latitudes and complete the cell.

The Atlantic MOC is formed by the northward surface flow of warm waters and by the southward deep flow of cold waters, resulting in a net heat transport to the north called Meridional Heat Transport (MHT).

AOML currently provides quarterly reports for the North and South Atlantic MHT using data from the AX07 and AX18 repeat XBT transects, respectively.

North Atlantic Meridional Heat Transport


South Atlantic Meridional Heat Transport


For further information, please consult the following webpages:



Garzoli, S.,M.O. Baringer, S. Dong, R. Perez, and Q. Yao, 2012: South Atlantic meridional fluxes. Deep-Sea Res., Part I, 71:21-32, doi:10.1016/j.dsr.2012.09.003. [PDF]

Dong, S., M. Baringer, G. Goni, and S. Garzoli, 2011: Importance of the assimilation of Argo Float Measurements on the Meridional Overturning Circulation in the South Atlantic. Geophys. Res. Lett., 38, L18603, doi:10.1029/2011GL048982. [PDF]

Baringer, M.O., and S.L. Garzoli, 2007: Meridional heat transport determined with expendable bathythermographs, Part I: Error estimates from model and hydrographic data. Deep-Sea Res., Part I, 54(8):1390-1401. [PDF]

Dong, S., S.L. Hautala, and K.A. Kelly, 2007: Interannual variations in upper-ocean heat content and heat transport convergence in the western North Atlantic. J. Phys. Oceanogr., 37(11):2682-2697. [PDF]