Spectral analysis of the δ O record shows significant peaks at solar periodicities of 208 yr and 86 yr suggesting variation is influenced by solar forcing.
This record shows not only 23-kyr precessional cycles punctuated by prominent millennial-scale weak monsoon events synchronous with Heinrich events in the North Atlantic, but also clear glacial–interglacial variations that are consistent with marine records but different from the cave records in East China.
The ISM is characterized by two regions of precipitation maxima: a narrow coastal region along the Western Ghats, denoted by ISM, where storms emanate from the Bay of Bengal and whose rainfall variability is well correlated with that of “All India” rainfall (1).
Multiple proxies obtained from Arabian Sea sediments have revealed the variability of summer monsoon winds on timescales of 10 precipitation on multiple timescales.
Thus, Holocene centennial- and multi-decadal-scale monsoon variability is significant, although not as large as glacial millennial-scale variability.
The monsoon shows a strong connection with northern South American hydrological changes related by changes in ITCZ position.