Influence of Vapor Source and Seasonality in Stable Isotope Compositions of Precipitation in Falakata, North Bengal

Tirkey, Mona Lisha (2014) Influence of Vapor Source and Seasonality in Stable Isotope Compositions of Precipitation in Falakata, North Bengal. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Mona Lisha Tirkey) Mona_Lisha_Tirkey.pdf - Submitted Version Restricted to Repository staff only Download (2MB)

Abstract

Stable isotopic composition (δD and δ¹⁸O) of two years of daily rainfall samples were collected from Falakata, Northern part of West Bengal and were analyzed. The δ¹⁸O value ranges from 6.3‰ to -16.5‰ and δD value ranges from 43.9‰ to -111.8‰. The Local Meteoric Water Line (LMWL) has comparable slope with lower intercept (δD = 7.47 δ¹⁸O + 3.50) to Global Meteoric Water Line (GMWL). Monsoonal rainfall during the later part of monsoon season exhibits lowest δ¹⁸O and δD values. There is a trend to lighter isotope values over the course of extent of monsoon. To determine the vapor source from which rainfall at Falakata derived, backward trajectories for time periods of 24-216 hours have been calculated by Hybrid Single-Particle Lagrangian Integrated Trajectories (HYSPLIT-4). Back-trajectory computations (Hysplit-4) have revealed that in monsoon period rainfall at study site is fed by Bay of Bengal (BOB) with significant contribution from Arabian Sea. During post- and pre-monsoon time along with BOB, the inland sources also supply considerable amount of moisture.

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