Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/cp-2017-77
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
07 Jul 2017
Review status
This discussion paper is under review for the journal Climate of the Past (CP).
Strengthening of the Somali upwelling during the Holocene and its impact on southwest monsoon rainfall
D. Balaji1,2, Ravi Bhushan2, and L. S. Chamyal1 1Department of Geology, The Maharaja Sayajirao University of Baroda, India
2Geoscience Division, Physical Research Laboratory, Ahmedabad, India
Abstract. The history of the Somali upwelling during the last 18.5 ka has been reconstructed using biogenic silica fluxes estimated from a sediment core retrieved from the western Arabian Sea. The reconstructed record demonstrates periodic weakening and strengthening of the Somali upwelling during the past 18.5 ka. Variations in biogenic silica fluxes suggest weak upwelling during the last glacial period (18.5–15 ka BP). Strengthened upwelling during the Bølling–Allerød period (15–13 ka BP) points to post-glacial onset of the southwest monsoon. The Younger Dryas (13–11 ka BP) is again marked by reduced upwelling strength. Intensification of the Somali upwelling at the beginning of the Holocene and a decline at 8 ka BP are observed. Increases in upwelling strength recorded since 8 ka BP suggest strengthening of the southwest monsoon during the latter part of the Holocene. Linking these upwelling variations with southwest monsoon precipitation, a major shift in the relationship between the strength of the Somali upwelling and southwest monsoon rainfall from positive to negative has occurred during the pre-Holocene to the Holocene. The observed shift is attributed to the variation in the southwest monsoon strength due to the latitudinal shift of the Intertropical Convergence Zone (ITCZ) associated with changes in moisture sources.

Citation: Balaji, D., Bhushan, R., and Chamyal, L. S.: Strengthening of the Somali upwelling during the Holocene and its impact on southwest monsoon rainfall, Clim. Past Discuss., https://doi.org/10.5194/cp-2017-77, in review, 2017.
D. Balaji et al.
D. Balaji et al.
D. Balaji et al.

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