Deeply penetrating banded zonal flows in the solar convection zone

Helioseismic observations have detected small temporal variations of the ro tation rate below the solar surface that correspond to the so-called "torsi onal oscillations" known from Doppler measurements of the surface. These ap pear as bands of slower- and faster-than-average rotation moving equatorwar d. Here we establish, using complementary helioseismic observations over 4 yr from the GONG network and from the MDI instrument on board SOHO, that th e banded flows are not merely a near-surface phenomenon: rather, they exten d downward at least 60 Mm (some 8% of the total solar radius) and thus are evident over a significant fraction of the nearly 200 Mm depth of the solar convection zone.