Indian monsoon variability and cyclicity studies from the Indian Ocean marine sediment cores.

Abstract

The Indian monsoon is a complex land-ocean-atmosphere coupled climate system which is critical and important to the lives of billions of population in the Indian subcontinent. In this present study, records of the signatures of Indian monsoon viz. sea surface temperatures (SST) and oxygen isotopes (� 18OSW) were collected, compiled and compared to dive into understanding of the variability of the Indian monsoon. A total of 21 datasets of SSTs and (� 18OSW) from the Indian marine sediment cores were used that have been previously published and publicly available. It was observed that the SSTs were much lower during the pre-Holocene period than the Holocene, while rapid increase in warming could be seen during the deglaciation across the Indian Ocean region. Similarly, the �18OSW records also show that the Indian monsoon were mostly weaker during the pre-Holocene, while intensifying during the deglaciation transition to stronger yet inconsistent monsoon till the late Holocene. Climate records from nearby surrounding regions are also in agreement with these records from the Indian Ocean suggesting implications and close relationship with the global system. REDFIT spectral analyses were also performed on these records and most of the yielded periodicities are observed to be closely associated with the solar insolation/cycles, thermohaline circulation system, suggesting a deep teleconnection with the North Atlantic climate system.