PMEL Publications Abstract
FY 1999
Thermocline ventilation and oxygen utilization rates in the subtropical North Pacific based on CFC distributions during WOCE
Sonnerup, R.E., P.D. Quay, and J.L. Bullister
Deep-Sea Res. I, 46(5), 777–805, doi: 10.1016/S0967-0637(98)00092-2 (1999)
Thermocline ventilation rates for the subtropical North Pacific are determined using a 1-dimensional (meridional) along-isopycnal advective-diffusive model tuned to chlorofluorocarbon (CFC) concentrations measured along 152°W in 1991 during WOCE P16. Mean southward advection rates in the subtropics range from 1.03 to 0.56 cm s−1 between σθ = 25.5 and 26.6. Model-derived ventilation times for the subtropical gyre increase from about 10 to 27 years for that isopycnal range. Oxygen utilization rates (OURs) determined using the advective-diffusive model decrease with depth from 6.6 to 3.2 µmol kg−1 yr−1 between σθ = 25.5 and 26.6. Extrapolation of the OUR versus depth trend to the base of the euphotic zone with the 1/Z power function of Martin et al. (1987) and integration from 500 to 100 m depth implies a carbon export rate from the overlying euphotic zone of 2.2 ± 0.5 moles C m−2 yr−2 at 30°N, 152°W. Analysis of the WOCE radiocarbon and salinity distributions indicates that zonal and crossisopycnal transport terms would have to be considered in modeling these tracers in the subtropical North Pacific.