Basin‐wide distributions of chlorofluorocarbons CFC‐11 and CFC‐12 in the North Pacific: 1985–1989

Abstract

All of the dissolved chlorofluorocarbon measurements made between 1985 and 1989 along several long zonal and meridional hydrographic sections in the North Pacific are presented in this manuscript. Chlorofluorocarbon (CFC) concentrations are displayed as functions of depth and density along the sections. Over much of the region studied, dissolved CFCs are observed to have penetrated to densities greater than those that outcrop at the surface in the North Pacific (σθ > 26.8). Maxima in CFC concentration are associated with remnant winter mixed layers and with mode waters. When the observed CFC concentrations from these sections are normalized to a common date and mapped onto five density surfaces in the North Pacific, it becomes apparent that the Sea of Okhotsk is an important location for the ventilation of the intermediate waters of the North Pacific. The CFC observations are used together with hydrographic data to study the pathways and timescales of circulation and ventilation processes in the upper and intermediate waters of the North Pacific. Using models of the increases of these compounds as a function of time, CFC “apparent ages” are calculated on these isopycnal surfaces. The CFC apparent ages are used together with observed apparent oxygen utilization to estimate oxygen utilization rates along these sections.