L'Atalante CASSIOPEE (GPc05)

Cruise plan

Cruise Info. 
Ship name (ship code)L'Atalante (35A3)
Cruise identifierCASSIOPEE (GPc05)
Cruise period2015-07-19 — 2015-08-23
Port of departureNoumea, New Caledonia
Port of returnNoumea, New Caledonia
ObjectivesThe study is aimed at solving the enigma posed by recently discovered mid-depth (>1000 m) jets in the equatorial Pacific regarding their origin, spatial extent, geochemical composition and role in fuelling productivity in the East Pacific. Integrated into other projects of the PIs in the South, West, and equatorial Pacific, the study will further address the temporal variability of the zonal current system and its geochemical properties. The study is designed as a concerted effort between geochemists and physical oceanographers and will directly combine high-resolution profiles of Nd isotopes and REE concentrations with detailed observations of ocean dynamics in the western tropical Pacific from the same stations and water depths.

The main research questions are:
1. are trace elements also supplied to the mid-depth currents (as has been shown for surface and subsurface currents)?
2. are all island margins in the West Pacific equally important trace element sources?
3. do the eastward flowing mid-depth zonal jets originate as discrete jets? If so, they may transport trace elements across the Pacific. If they are instead fed by recirculation from other currents, they would take in a less important role in the eastward transport of trace elements and micronutrients.
Chief scientistFrederic Marin (Institute for Development for Research (IRD), Noumea)
Ocean/sea areas 
GeneralNorth Pacific Ocean
SpecificTropical West Pacific
Data held at BODC 
Discrete samples 
25  CTD frame plus rosette sampler