Moisture rainout fraction over the Indian Ocean during austral summer based on O-18/O-16 ratios of surface seawater, rainwater at latitude range of 10 degrees N-60 degrees S

Prasanna, K and Ghosh, Prosenjit and Bhattacharya, SK and Rahul, P and Yoshimura, Kei and Anilkumar, N (2018) Moisture rainout fraction over the Indian Ocean during austral summer based on O-18/O-16 ratios of surface seawater, rainwater at latitude range of 10 degrees N-60 degrees S. In: JOURNAL OF EARTH SYSTEM SCIENCE, 127 (4).

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Abstract

Oxygen isotope ratios () of surface seawater and rainwater samples from the Indian Ocean region () during austral summer collected onboard ORV Sagar Nidhi during 2011-2013 have been measured along with salinity, sea surface temperature and relative humidity. The rainwater is isotopically lighter (by compared to the equilibrium condensation of the vapour arising from the seawater at the ambient condition. The isotopic composition of the vapour at high altitude responsible for the rain formation at the sampling location is estimated from a global atmospheric water isotope model (IsoGSM2). The apparent deficit of 5 can be explained by invoking a high degree of rainout (on average, about 70% of the overhead atmospheric moisture) during transport of the source vapour to the sampling location undergoing a Rayleigh fractionation. The required rainout fraction is higher (80%) in the latitude belt compared to the equatorial belt (60%). The pattern of variation in the rainout fraction with latitude is consistent with the well-known evaporation/precipitation processes in the Indian Ocean.

Item Type:	Journal Article
Publication:	JOURNAL OF EARTH SYSTEM SCIENCE
Publisher:	INDIAN ACAD SCIENCES, C V RAMAN AVENUE, SADASHIVANAGAR, P B #8005, BANGALORE 560 080, INDIA
Additional Information:	Copy right of this article belong to INDIAN ACAD SCIENCES, C V RAMAN AVENUE, SADASHIVANAGAR, P B #8005, BANGALORE 560 080, INDIA
Department/Centre:	Division of Mechanical Sciences > Centre for Earth Sciences Division of Mechanical Sciences > Divecha Centre for Climate Change
Date Deposited:	19 Jun 2018 14:46
Last Modified:	25 Feb 2019 11:24
URI:	http://eprints.iisc.ac.in/id/eprint/60036

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