Near bottom currents and their relation to the transport in the Kuroshio Extension

Abstract

Near bottom current structure in the area of the Kuroshio Extension is examined using Lowered ADCP data obtained along 146°25′E and 152°30′E. The flow of the Kuroshio Extension reaches the ocean floor with a shift of the current to the right with depth. The near bottom currents have speeds of over 10 cm/s. Westward deep counter currents are observed to the north and south of the near bottom Kuroshio Extension. The eastward Kuroshio Extension transport is 163 Sv across 146°25′E and 113 Sv across 152°30′E, larger than previous studies because the contribution of the barotropic flow is twice that of the geostrophic flow. The downstream variation of the transport suggests the Kuroshio Extension strength increases after separating from the coast of Japan and decreases before 152°30′E. However, temporal variability could also contribute to the different transport estimates.