Local versus remote influences on decadal oxygen variability at Ocean Station Papa

Precious Mongwe, Nation Center for Atmospheric Research, Climate and Global Dynamics (CGD), Boulder, CO, United States, Matthew C Long, [C]Worthy, LLC, Boulder, United States and Takamitsu Ito, Georgia Institute of Technology, Atlanta, United States
Abstract:
The variance spectrum of thermocline dissolved oxygen has significant power on decadal to multi-decadal timescales, linked to ventilation and circulation dynamics. However, the mechanisms that drive specific variations in O2 remain poorly understood. This study uses a suite of hindcast and idealized numerical experiments in concert with in situ observations to examine mechanisms regulating decadal changes in O2 in the North Pacific. Preliminary results indicate that over 60% of O2 variance on the 26.5 isopycnal surface at Ocean Station Papa is explained by decadal oxygen changes in the western North Pacific outcrop region with a 4-6 year lag. Oxygen anomalies are generated in the outcrop region and transported to the east in the large-scale gyre flow. The forcing mechanisms producing variation in oxygen in the western are related to atmospheric modes of variability; interannual variation in surface momentum and buoyancy forcing drive variation in mixed layer depths and O2 subduction rates. Variation in interior oxygen consumption plays a negligible role in the decadal variability of O2 on the 26.5 isopycnal. This study demonstrates the dominant role of remote drivers related to the decadal variability O2 at Ocean Station Papa.