High Resolution Southwest Monsoon Reconstruction for the Past ~2,800 Years: Wind Versus Precipitation

Abstract

The wind-induced, upwelling-related productivity records from the western Arabian Sea have been used to reconstruct past variations in the Southwest (SW) monsoon wind strength. In contrast, the eastern Arabian Sea stores precipitation signal as it receives abundant freshwater, either as overhead precipitation or as surface runoff from the adjacent Western Ghats during the SW monsoon. A sediment core, SK 145-9 (12.6°N, 74.3°E; water depth 400 m, analyzed AMS dated length 50 cm-spanning past ~2,800 years) from the eastern Arabian Sea, was analyzed with high-resolution (sub-centennial) for δ18O and δ13C variations in three different species of planktic foraminifera (Globigerinoides ruber, Globigerinoides sacculifer and Globorotalia menardii) that documents past precipitation changes. Periods of aridity were observed at ~2,000, 1,500, 1,100, 850 and 500 cal yr BP (calibrated ages) in the eastern Arabian Sea, which were matched with data from western Arabian Sea depicting wind intensity. The wind strength exhibits good correlation with the precipitation intensity; reduced precipitation is accompanied by weakened winds, thus providing the paleoclimatic evidence for the control exhibited by SW monsoon precipitation over the wind strength via latent heat release.KeywordsBefore PresentWind StrengthPlanktic ForaminiferaAccelerator Mass SpectrometerGlobigerinoides RuberThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.