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Craig-Gordon model validation using stable isotope ratios in water vapor over the Southern Ocean

Shabir Dar, C and Ghosh, P and Swaraj, A and Kumar, A (2020) Craig-Gordon model validation using stable isotope ratios in water vapor over the Southern Ocean. In: Atmospheric Chemistry and Physics, 20 (19). pp. 11435-11449.

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Official URL: https://doi.org/10.5194/acp-20-11435-2020


The stable oxygen and hydrogen isotopic composition of water vapor over a water body is governed by the isotopic composition of surface water and ambient vapor, exchange and mixing processes at the water air interface, and the local meteorological conditions. These parameters form inputs to the Craig Gordon models, used for predicting the isotopic composition of vapor produced from the surface water due to the evaporation process. In this study we present water vapor, surface water isotope ratios and meteorological parameters across latitudinal transects in the Southern Ocean (27.38 69.34 and 21.98 66.8 S) during two austral summers. The performance of Traditional Craig Gordon (TCG) (Craig and Gordon, 1965) and the Unified Craig Gordon (UCG) (Gonfiantini et al., 2018) models is evaluated to predict the isotopic composition of evaporated water vapor flux in the diverse oceanic settings. The models are run for the molecular diffusivity ratios suggested by Merlivat (1978), Cappa et al. (2003) and Pfahl and Wernli (2009), referred to as MJ, CD and PW, respectively, and different turbulent indices (x), i.e., fractional contribution of molecular vs.Turbulent diffusion. It is found that the UCGMJ xD0:8, UCGCD xD0:6, TCGMJ xD0:6 and TCGCD xD0:7 models predicted the isotopic composition that best matches with the observations. The relative contribution from locally generated and advected moisture is calculated at the water vapor sampling points, along the latitudinal transects, assigning the representative end-member isotopic compositions, and by solving the two-component mixing model. The results suggest a varying contribution of the advected westerly component, with an increasing trend up to 65 S. Beyond 65 S, the proportion of Antarctic moisture was found to be prominent and increasing linearly towards the coast. © 2020 Copernicus GmbH. All rights reserved.

Item Type: Journal Article
Publication: Atmospheric Chemistry and Physics
Publisher: Copernicus GmbH
Additional Information: The copyright for this article belongs to the Authors.
Keywords: https://acp.copernicus.org/articles/20/11435/2020/diffusivity; hydrogen isotope; isotopic composition; isotopic ratio; oxygen isotope; stable isotope; surface water; water vapor, Southern Ocean
Department/Centre: Division of Mechanical Sciences > Centre for Earth Sciences
Division of Mechanical Sciences > Divecha Centre for Climate Change
Date Deposited: 11 Jan 2023 06:18
Last Modified: 11 Jan 2023 06:18
URI: https://eprints.iisc.ac.in/id/eprint/79042

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