SIMILARITIES OF THE DEACON CELL IN THE SOUTHERN-OCEAN AND FERREL CELLS IN THE ATMOSPHERE

The meridional circulation hi the ocean and the atmosphere, when avera ged over longitude and time at constant height, shows a number of cell s. Most of these appear as direct circulations, with ascent in respons e to forcing which reduces the density. There are several indirect cir culations, particularly the Deacon cell in the Southern Ocean and the Ferrel cells in the mid-latitude atmosphere, which appear to act again st the mean density-gradient in regions of no apparent mean density-fo rcing. When the zonal-mean circulation is calculated in density coordi nates, both the Deacon cell and the Ferrel cells disappear. A transfor mation of the zonal-mean circulation as a function of height is used t o give the residual mean circulation, which is remarkably similar to t he zonal-mean circulation in density coordinates in both the Southern Ocean and the atmosphere. This shows that the existence of the Deacon and Ferrel cells is the result of correlations of zonal variations of density and meridional flow, and not of zonal-mean density-forcing. Zo nal variations associated with the time-mean eddies in the Southern Oc ean are the main contributors to the Deacon cell, while correlations i n transient weather systems are the major factor leading to Ferrel cel ls.