A 2,200 years periodicity in the Asian Monsoon System

Abstract

We have carried out a high‐resolution study of fluctuations in upwelling intensity along the Oman Margin, western Arabian Sea, through the last 19,130 years based on several marine microfossil indices of upwelling. 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 periodicity. Our data further demonstrate greater amplitude in the variability of the SW monsoon during the Holocene than during the last glacial 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 periodicity in atmospheric 14C might be induced by oceanic circulation changes.