A Numerical Study on Isotopic Variation of Meltwater from Isotopically Heterogeneous Snowpack or Ice

Abstract:

Isotopic evolution of snowmelt from a seasonal snowpack is an important component for both hydrological and climate studies. Numerous studies have examined the isotopic exchange between snow and its meltwater during the melting of isotopically homogeneous snowpack or ice. In this work, we aim to examine the changes in the isotopic composition of meltwater from an isotopically differed two-layered snowpack or ice by a one-dimensional model developed by Feng et al. (2002). The model was simulated by changing the parameters including the effectiveness of exchange (ψ), the ice-to-liquid ratio of the exchange system (f), and the percolation velocity (u*). Moreover, experimental data were compared to obtain the best fit value of the isotopic exchange rate constant. The steep and gradual alteration was observed in the isotopic composition of the meltwater depending on the difference of the initial isotopic composition of top and bottom layers. The pattern and range of the isotopic variations of the meltwater were shown to be more sensitive to the ice-to-liquid ratio of the exchange system (f) and the effectiveness of exchange (ψ). The results of this study could be useful for the better quantification of isotopic alteration of meltwater under the hydrological and climate studies.