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Ocean Science An interactive open-access journal of the European Geosciences Union
© Author(s) 2006. This work is licensed under
the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.
25 Jul 2006
Review status
This discussion paper is a preprint. It has been under review for the journal Ocean Science (OS). A final paper in OS is not foreseen.
Distribution and transport processes of marine particulate matter off Cape Blanc (NW-Africa): results from vertical camera profiles
N. Nowald1, G. Karakas2, V. Ratmeyer1, G. Fischer1, R. Schlitzer2, R. A. Davenport1, and G. Wefer1 1University of Bremen, Department of Geosciences, Klagenfurterstrasse, 28359 Bremen
2Alfred Wegener Institute Foundation for Polar and Marine Research, Bürgermeister-Smidt-Straße 20, 27568 Bremerhaven
Abstract. In this study, we present vertical particle profiles acquired with the deep-sea camera system ParCa. The profiles were obtained during three campaigns in the spring seasons of 2001–2003 off NW-Africa (Cape Blanc). The camera profiles showed interannual and spatial variabilities regarding the particle concentrations in the ocean surface which were related to changes in the Chl-a biomass concentration. Although particle concentrations varied, all profiles showed rather similar distribution patterns. They were characterised by a subsurface particle maximum layer, around 200 m at stations close to the coast and around 400 m at stations further offshore. We argue, that at least a portion of the material seen in the subsurface maximum originates from the coast, and was laterally advected towards the open ocean by filament activity. Apart from this offshore transport, increased concentrations of particulate matter above the seafloor suggest a downslope transport of particulate matter near the seafloor. Both hypothesis were tested with model computations, described in a companion paper. A special sedimentation event was observed during a field campaign in 2001. The particle abundance patterns and the size distributions most likely reflect a sinking event, where particulate matter is transferred on very short time scales from the surface to the seafloor. We assume, that the fast sinking particle cloud preferably scavenges the more abundant small particles, resulting in larger particles sizes above and within the sinking cloud.

Citation: Nowald, N., Karakas, G., Ratmeyer, V., Fischer, G., Schlitzer, R., Davenport, R. A., and Wefer, G.: Distribution and transport processes of marine particulate matter off Cape Blanc (NW-Africa): results from vertical camera profiles, Ocean Sci. Discuss.,, 2006.
N. Nowald et al.
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
RC S389: 'Poorly representative data', Anonymous Referee #2, 06 Sep 2006 Printer-friendly Version 
AC S592: 'Interactive comment to referee #2', Nicolas Nowald, 17 Oct 2006 Printer-friendly Version 
N. Nowald et al.
N. Nowald et al.


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