Variations of the Somali upwelling since 18.5 ka BP and its relationship with southwest monsoon rainfall
<p>Somali upwelling history has been reconstructed for the last 18.5 ka BP based on biogenic silica fluxes estimated from a sediment core retrieved from the western Arabian Sea. Surface winds along the east African coast during the southwest monsoon (SWM) cause the Som...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-09-01
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| Series: | Climate of the Past |
| Online Access: | https://www.clim-past.net/14/1331/2018/cp-14-1331-2018.pdf |
| Summary: | <p>Somali upwelling history has been reconstructed for the last 18.5 ka BP based on
biogenic silica fluxes estimated from a sediment core retrieved from the
western Arabian Sea. Surface winds along the east African coast during the
southwest monsoon (SWM) cause the Somali upwelling; thus, the intensity of this
upwelling has been related to the variability of the SWM. Biogenic
silica flux variation suggests periodic weakening and strengthening of the
Somali upwelling. Weakened upwelling during the 18.5–15 ka BP period and strengthened
upwelling during the Bølling–Allerød (15–12.9 ka BP) suggest the onset of
the SWM. The Younger Dryas (12.9–11.7 ka BP) is marked
by reduced upwelling strength, with an intensification of the Somali upwelling
observed at the beginning of the Holocene and a further decline at 8 ka BP.
The increase in the upwelling strength recorded since 8 ka BP suggests SWM
strengthening during the latter part of the Holocene. A comparison of
upwelling variations with the SWM precipitation record
demonstrates a reversal in the relationship between the strength of the Somali
upwelling and SWM rainfall at the beginning of the Holocene.
This observed shift has been attributed to the variation in the SWM
strength due to the latitudinal shift of the intertropical
convergence zone (ITCZ) associated with changes in moisture sources.</p> |
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| ISSN: | 1814-9324 1814-9332 |