The Effect of Monsoon Circulation on the Stable Isotopic Composition of Rainfall. Issue 10 (29th May 2018)

• Record Type: Journal Article
• Authors: Midhun, M.; Lekshmy, P. R.; Ramesh, R.; Yoshimura, Kei; Sandeep, K. K.; Kumar, Samresh; Sinha, Rajiv; Singh, Ashutosh; Srivastava, Shalivahan
• Is Part Of: Journal of geophysical research. Volume 123:Issue 10(2018)
• Page Start: 5205
• Page End: 5221
• Publication Date: 2018-05-29
• Subjects: stable isotope -- Indian monsoon -- monsoon circulation; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2017JD027427
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Understanding the factors that control the variability of oxygen isotopic ratios (δ 18 O) of Indian Summer Monsoon (ISM) rainfall (δ 18 Op ) is of vital importance for the interpretation of δ 18 Op derived from climate proxies (e.g., speleothem and tree ring cellulose) of this region. Here we demonstrate the importance of moisture transport pathways on spatiotemporal variations of ISM δ 18 Op using a new set of daily observations from central and northern India and previously reported data aided by simulations from an isotope‐enabled General Circulation Model. 18 O‐depleted rain events are characterized by a higher number of air parcel back trajectories through the Bay of Bengal branch of moisture transport, while those through the Arabian Sea branch are associated with 18 O enriched rain events. This effect is observed on intraseasonal to interannual timescales in the long‐term observations at New Delhi as well. Thus, the shift in moisture transport regimes must be considered when interpreting δ 18 Op from climate proxies of the ISM region. Key Points: We present a new data set of rain δ 18 O and δD of Indian Summer Monsoon Rain δ 18 O over central and northern India is influenced by varying moisture transport pathways Isotope‐enabled GCM captures intraseasonal variations in rain δ 18 O