Upper and intermediate circulation in the western equatorial Pacific Ocean in October 1999 and April 2000

The upper and intermediate circulation (0–1200 m) in the western equatorial Pacific Ocean is examined thanks to Lowered Acoustic Doppler Current Profiler (LADCP) measurements carried out during two cruises in October 1999 and April 2000. Several new features of the equatorial circulation are discussed. It is shown that the secondary South Subsurface CounterCurrent (sSSCC) laying at 6°S–400 m depth, had a deep extension at 165°E with a maximum core velocity around 5°S–1000 m. Furthermore the Equatorial Intermediate Current (EIC) and the Lower EIC (LEIC) displayed a strong temporal variability between 165°E and 180°, as these two westward currents were replaced by eastward flow along the equator on the second cruise. Finally during the April 2000 cruise the zonal velocity profile carried out at the equator east of the Gilbert Island (around 175°E) broke into small vertical scales, possibly reflecting topographic effect and/or destabilization mechanism that leads to the formation of long zonal jet‐like structures.