The structure of a Stommel type of frictional western boundary layer i
n a thermally driven two-layer model is examined. Instead of specifyin
g the interfacial upwelling a priori, it is calculated as part of the
solution subject to the dynamic and thermodynamic constraints. it is s
hown that upwelling prevails in the western boundary. Scaling analysis
indicates that upwelling within the western boundary layer is two ord
ers of magnitude stronger than that in the ocean interior. Furthermore
, the total amount of upwelling within the western boundary layer cons
titutes a substantial parr of the basin-integrated upwelling. Thus, ou
r results suggest that it is important to study the dynamic role of we
stern boundary upwelling in ocean circulation models.