METEOR M181

The Transatlantic Equatorial Cruise 2 (TRATLEQ2) is an interdisciplinary cruise focusing on upwelling in the tropical Atlantic. Main topics are the physical forcing of upwelling, its importance for biological production and plankton communities, associated chemical cycles, as well as the current system setting the background conditions for the downward carbon export. TRATLEQ2 is already the second cruise during which an integral approach of physical, chemical, biogeochemical and biological measurements will be apllied, extending over the whole equatorial section from the eastern to the western boundary.
Beside the equatorial Atlantic, another study area is the coastal upwelling off Angola,
where the same techniques will be applied to better understand the functioning of this
tropical upwelling system. A particular focus is on the export flux of carbon to mesopelagic and bathypelagic depths associated with particle flux and diel vertical zooplankton migration.

The main scientific questions that will be addressed during M181 are:
• What sets the strength and the variability of upwelling at the equator and at the eastern boundary of the South Atlantic?
• What are the relations and feedbacks linking equatorial and eastern boundary upwelling with biological productivity, downward carbon export and air-sea exchange of heat and trace gases?

During M181, we will study the variability of oceanic circulation with a focus on the poleward Angola Current and mixing processes on the shelf and at the continental slope off Angola.
Other main focuses of M181 are particulate matter fluxes, zooplankton/nekton dynamics, and zooplankton/nekton particle interactions.