Possible zonal asymmetry of the Indian summer monsoon rainfall after ~5 ka BP as revealed by palaeo-salinity in the eastern Arabian Sea

Banakar, VK and Baidya, S and Shankar, D and Nanjundiah, RS and Jain, V (2022) Possible zonal asymmetry of the Indian summer monsoon rainfall after ~5 ka BP as revealed by palaeo-salinity in the eastern Arabian Sea. In: Journal of Earth System Science, 131 (3).

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Abstract

Abstract: Data from a high-resolution sediment core off Goa in the eastern Arabian Sea (EAS) show that the Holocene surface-salinity variation off Goa contains four alternating high- and low-salinity events. These events are in contrast with the Bay-of-Bengal (BoB) surface-salinity variation after 5 ka BP, suggesting an asymmetry in the rainfall associated with the Indian summer monsoon over the eastern and western parts of the Indian subcontinent and its surrounding seas. This zonal asymmetry in rainfall is also seen in modern rainfall data. The historical rainfall over the Indian subcontinent indicates that the Northwest India and West Peninsular India and their rainfall subdivisions, which feed freshwater to the EAS, are mutually strongly correlated, but they are not correlated with Northeast India and North Central India and their subdivisions, which feed freshwater to the BoB. This mid-Holocene zonal asymmetry in rainfall over the eastern and western parts of the subcontinent appears to have sustained through to modern times. The Holocene salinity events off Goa are closely comparable to the evolution of Harappan Civilization in the Indus Valley, suggesting that the Holocene salinity variation in the EAS is connected to, and is a reliable indicator of, rainfall over the Harappan Civilization Region. Research Highlights: 1.High-resolution core data off Goa show four alternating high- and low-salinity events during the Holocene.2.These events are coherent with the Bay of Bengal (BoB) surface-salinity variation till ~5 ka BP, but diverge thereafter.3.This zonal contrast between the eastern and western parts of the Indian subcontinent is also seen in modern rainfall data.4.This zonal asymmetry in rainfall may be associated with the northward propagation of rain bands and northwestward movement of low-pressure systems.5.The analysis favours a flood-forced decline of the Harappan Civilisation.

Item Type:	Journal Article
Publication:	Journal of Earth System Science
Publisher:	Springer
Additional Information:	The copyright for this article belongs to the Springer.
Keywords:	Eastern Arabian Sea; Harappan Civilization; historical rainfall analysis; Holocene; Indian summer monsoon; Indus Valley; surface salinity
Department/Centre:	Division of Mechanical Sciences > Divecha Centre for Climate Change Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited:	04 Aug 2022 09:14
Last Modified:	04 Aug 2022 09:14
URI:	https://eprints.iisc.ac.in/id/eprint/75287

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