= 27.35 kg m3, will be compared with the results from
the Sverdrup model. For this purpose the model transport is projected onto
the geostrophic transport and both transports are integrated from north
to south. The transports in Fig. 9 are in qualitative
agreement. North of 40oS there is an acceptable quantitative
agreement of the simulated with the observed transport, considering that
the hydrographic and the wind data were obtained in different years. Especially
the simulated transport of about 30 Sv in the westward branch of
the subtropical gyre and the location of the gyre center agree well with
the oceanic observations. There are, however, two obvious discrepancies
between the simulation and the observation. First, the width and location
of the westward transport band in the model differs from the oceanic observation.
Secondly, the simulated transport in the eastward current is significantly
weaker than the observed transport, the difference is about 20 Sv.
Comparison of the simulated transport with the observed transport while excluding the AAIW layer yields the following: The observed eastward transport between 40oS and 52oS is reduced from 59 Sv to 30 Sv (Fig. 9 and Tab 4a) and the westward transport between 21oS and 33oS is reduced from 29 Sv to 17 Sv (Fig. 9 and Tab 5a). These two transports (30 Sv to the east and 17 Sv to the west) are smaller than those predicted by the Sverdrup model. We think this is unlikely, mainly due to the out- and inflow at the eastern boundary. Therefore we conclude that the AAIW layer is likely to be part of the subtropical gyre, and that a better understanding of the AAIW circulation can be reached by applying a model of the ventilated thermocline to the subtropical region in the South Atlantic.
