Possibility of using isotopic composition of ground-level vapour for monitoring arrival and withdrawl of southwest monsoon

Abstract

Stable isotopes of oxygen and hydrogen have long been used to trace the hydrological processes1 on the principle that the lighter isotopes of water (e.g. H2O) preferentially evaporate over its heavier isotopes (e.g. HDO or H2 18O), and the heavier isotopes preferentially condense2. In this line, several studies3–5 were carried out all over the world to characterize the local meteoric lines for generalizing the amalgamation of various hydrological processes taking place over multiple temporal and spatial scales. These studies may be able to provide us the precise analysis of a synoptic event due to the dependence on many physical and atmospheric processes 6. Isotopic composition of moisture depends upon many processes like transportation, condensation, precipitation and re-evaporation of moisture. The composition of the vapourplus- condensed water additionally depends on microphysical processes that determine the fraction of condensed water that is converted to precipitation.