The influence of the SW monsoon on the deep-sea organic carbon cycle in the Holocene

Results from long-term sediment trap experiments carried out since 1986 in the western, central, and eastern Arabian Sea are combined with satellite-derived wind fields and paleoceanographic information to link the intensity of the SW monsoon to organic carbon fluxes and its preservation in sediments. The SW monsoon is characterized by the low-level jet (Findlater Jet) that crosses the Arabian Sea almost parallel to the Arabian coast. The intensity of the Findlater Jet mainly controls the velocities of upwelling that occurs to the northeast of the jet. Since up welling. in turn, mainly governs the organic carbon fluxes in the western Arabian Sea, variation in the strength of the Findlater Jet is the dominant factor determining the organic carbon fluxes on seasonal time scales. Changes in the subsurface nutrient concentrations due to variations in the surface ocean current systems seem to be another factor influencing the organic carbon fluxes, mostly on interannual time scales. The translation of sedimentary organic carbon burial rates into organic carbon fluxes according to Jahnke (1996). Global Biogeochemical Cycles 10, 71-88) allows us to extend our reflections also to a millennium time scale. This indicates that changes in the SW monsoon intensity as observed during the last decade could almost account for the range of organic carbon fluxes deciphered from the Holocene record. (C) 2000 Elsevier Science Ltd. All rights reserved.