Contribution of Mesoscale Eddies to the Subduction and Transport of North Pacific Eastern Subtropical Mode Water

This study investigates the contribution of mesoscale eddies to the subduction and transport of North Pacific Eastern Subtropical Mode Water (ESTMW) using the high-frequency output of an eddy-resolved ocean model spanning the period 1994–2010. Results show that the subduction induced by mesoscale eddies accounts for about 31% of the total subduction of ESTMW formation. The volume of ESTMW trapped by anticyclonic eddies is slightly larger than that trapped by cyclonic eddies. The ESTMW trapped by all eddies in May reaches up to about 2.8 × 1013 m3, which is approximately 16% of the total ESTMW volume. The eddy-trapped ESTMW moves primarily westward, with its meridional integration at 18°–30°N reaching about 0.17 Sv, which is approximately 18% of the total zonal ESTMW transport in this direction, at 140°W. This study highlights the important role of eddies in carrying ESTMW westward over the northeastern Pacific Ocean.