We have carried out a high-resolution study of fluctuations in upwelli
ng intensity along the Oman Margin, western Arabian Sea, through the l
ast 19,130 years based on several marine microfossil indices of upwell
ing. We document a periodicity of 2,200 years in the upwelling indices
, which would be governed by the South-west (SW) monsoon with such a p
eriodicity. Our data further demonstrate greater amplitude in the vari
ability of the SW monsoon during the Holocene than during the last gla
cial period. Our reported 2,200 years periodicity has two implications
(1) oceanic circulation changes partly influence monsoon strength at
sub-Milankovitch cycles (2) previously documented 2,300 years periodic
ity in atmospheric C-14 might be induced by oceanic circulation change
s.