New cruise proposal with RV Sonne for a GEOTRACES section in the South Indian Ocean (GIO6) (submitted 30th September 2014 ) Martin Frank, Eric Achterberg, Andrea Koschinsky, GEOMAR, Jacobs University Bremen, CAU Kiel, MPI Bremen, MPI Mainz, AWI Bremerhaven

Tentative extended plan for the Indian Ocean including cross over stations

Proposed detailed cruise track and stations

WOCE IO3 – oxygen distribution

Schematic surface water circulation of the Mozambique Channel – Inflow of NADW at depth Lutjeharms, 2006

Phytoplankton bloom of uncertain origin east of Madagascar

Main Goals: Zonal sections of TEI distribution (all key TEIs plus a range of others and speciation work) across the South Indian Ocean together with extensive investigations of the N-cycle (N2 fixation) and driving forces of vast phytoplankton blooms east of Madagascar (micronutrients). TEI relationships to major surface and subsurface ocean circulation in the South Indian Ocean, one of the least studied regions of the world‘s ocean (ins and outs of the Indian Ocean including particularly the margins. Sections to investigate the influence of dissolved and particulate inputs by the Zambezi River. Influence of dust inputs from the South African (Australian) deserts Hydrothermal inputs at the Central Indian Ridge