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-d erived wind fields and paleoceanographic information to link the intensity of the SW monsoon to organic carbon fluxes and its preservation in sediment s. The SW monsoon is characterized by the low-level jet (Findlater Jet) tha t crosses the Arabian Sea almost parallel to the Arabian coast. The intensi ty of the Findlater Jet mainly controls the velocities of upwelling that oc curs 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 str ength of the Findlater Jet is the dominant factor determining the organic c arbon fluxes on seasonal time scales. Changes in the subsurface nutrient co ncentrations due to variations in the surface ocean current systems seem to be another factor influencing the organic carbon fluxes, mostly on interan nual time scales. The translation of sedimentary organic carbon burial rate s into organic carbon fluxes according to Jahnke (1996). Global Biogeochemi cal Cycles 10, 71-88) allows us to extend our reflections also to a millenn ium time scale. This indicates that changes in the SW monsoon intensity as observed during the last decade could almost account for the range of organ ic carbon fluxes deciphered from the Holocene record. (C) 2000 Elsevier Sci ence Ltd. All rights reserved.