North Brazil Current Rings Experiment : mooring S1 data report, November 1998 - June 2000

Abstract

Nineteen months of temperature and salinity data were recovered from North Brazil Current (NBC) Rings Experiment Mooring S1. The mooring, located east of Barbados at 13º 00’N, 57º 53’W between November 1998 and June 2000, consisted of a vertical array of five temperature/conductivity recorders, five temperature recorders, one 150 kHz acoustic Doppler current profiler (ADCP), and one 260 Hz RAFOS sound source. This instrumentation was distributed over a depth interval (500-1100m) coincident with the low-salinity core of Antarctic Intermediate Water. Due to low concentration of scattering particles at 1000 m, the ADCP failed to return useful velocity data. Heading, pitch, and roll data were successfully recorded, however, and provide coarse measurement of current intensity. Four anomalously low temperature, low salinity, and (inferred) high-velocity events appear toward the end of the record. The temperature and salinity fluctuations observed during these events are most likely due to a combination of vertical instrument excursions due to current-induced mooring tilt and advection of anomalous NBC ring-core water past the mooring site. Anomalous conditions persist for a period of 2-3 weeks and appear, based on simultaneous surface drifter trajectories and satellite ocean color observations, to be associated with the passage of NBC Rings near Barbados.