Collaborative Research: P2C2--Subdecadal Pleistocene Indian Monsoon Variability: A Dual Archive Perspective

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The research team seeks to use the Pleistocene record of Indian Monsoon variation to examine how subdecadal rainfall dynamics change under disparate mean-states and global boundary conditions to refine the current understanding of the Indian Monsoon system’s response to climate forcing. Although Pleistocene archives have provided several essential insights into Indian Monsoon dynamics, inferences into subdecadal monsoon variability have been absent due to insufficient sample resolution. Previous reconstructions indicate strong mean-state monsoon responses to variations in insolation and greenhouse gas forcing, but the manner in which subdecadal variability is modulated across these periods is unclear. The current research effort focuses on periods with vastly different greenhouse gas, insolation, and ice-volume conditions to outline the sensitivity of monsoon seasonality and its short-term variability to global climate change. The researchers will apply imaging and mass spectrometric techniques to extract subdecadal hydroclimate signals from previously collected archives from terrestrial and oceanic realms of the Indian subcontinent. Specifically, the team will use previously collected cave stalagmites from peninsular India and sediments from Site U1446 in the Bay of Bengal, for which coarser-scale records of paleomonsoon variability have already been generated.The goal of the research is to help confirm or refute the following hypothesis: (1) seasonality and interannual monsoon variability exhibit a fast (instantaneous) response to gradual insolation forcing; (2) summer and winter monsoon dynamics vary out-of-phase with each other across disparate Pleistocene climate states; and (3) seasonal rainfall in the core monsoon zone and peninsular India is modulated similarly by external forcing.The potential Broader Impacts include integrating state-of-the-art geochemical techniques alongside paleoclimate dynamics to advance knowledge on how climate forcing modulates short-term Indian Monsoon variability and its extremes. The project will support a postdoctoral scholar and will significantly expand her research portfolio. The project will also support undergraduate researchers from underrepresented backgrounds at the University of Arizona and will involve southern Arizona high school students through the SARSEF program. This work will strengthen previously established collaborations between US and Indian scientists, which has enabled successful collection of samples in a societal responsible and mutually beneficial manner.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.