An intermediate-complexity atmospheric model coupled with a simple land-sur
face model and a mixed-layer ocean model is used to investigate the process
es involved in an idealized monsoon occurring on a single rectangular conti
nent. Idealized divergences of ocean heat transports are specified as an an
nual average 'Q-flux'. In this simple coupled configuration, the mechanisms
that affect land-ocean contrast and, in turn, the seasonal movement of the
continental convergence zones are examined. These include soil-moisture fe
edbacks; cooling of tropical oceans by ocean transport; ventilation, define
d as the import into continental regions of low moist static-energy air fro
m ocean regions where heat storage opposes summer warming; and the 'interac
tive Rodwell-Hoskins mechanism', in which Rossby-wave-induced subsidence to
the west of monsoon heating interacts with the convection zone. The fixed
ocean transports have a substantial impact on the continental convection. I
f Q-flux is set to zero, subtropical subsidence and ventilation tend to sub
stantially limit the poleward movement of summer monsoon rainfall. When lan
d hydrology feedbacks are active. the drying of subtropical continents disf
avours continental convection even in the tropics. When ocean transports ar
e included, tropical oceans are slightly disfavoured as regions for produci
ng convection which, by contrast, favours continental convection. The monso
on circulation then produces moisture transport from the ocean regions that
allows substantial progression of convection into the subtropics over the
eastern portion of the continent. The western portion of the continent tend
s to have a dry region of characteristic shape. This east-west asymmetry is
partly due to the interactive Rodwell-Hoskins mechanism. The ventilation i
s of at least equal importance in producing cast-west asymmetry and is the
single most important process in limiting the poleward extent of the contin
ental convection zone.