Subduction/obduction rate in the North Pacific diagnosed by an eddy-resolving model

Ventilation in the North Pacific is examined using data from the eddy-resolving 1/12° global HYbrid Coordinate Ocean Model (HYCOM) and QuikSCAT wind stress data. For the period January 2004 to December 2006 and area 20°–40°N, the total annual subduction rate is estimated at 79 Sv, and the obduction rate 41 Sv. Resolving the small-scale and high-frequency components of the eddy field can increase the subduction rate by 42 Sv, and obduction by 31 Sv. Lateral induction is the dominant contributor to enhancement of subduction/obduction, and temporal change of mixed layer depth has a secondary role. Further analysis indicates that the high-frequency components of the eddy field, especially those with timescale shorter than 10 days, are the most critical factor enhancing subduction/obduction.