Precipitation stable isotope variability and subcloud evaporation processes in a semi‐arid region

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dc.contributor.authorCrawford, Jen_AU
dc.contributor.authorHollins, SEen_AU
dc.contributor.authorMeredith, KTen_AU
dc.contributor.authorHughes, CEen_AU
dc.date.accessioned2021-03-04T05:10:57Zen_AU
dc.date.available2021-03-04T05:10:57Zen_AU
dc.date.issued2016-04-14en_AU
dc.date.statistics2021-03-04en_AU
dc.description.abstractThe stable isotopic (2H/1H and 18O/16O) composition of precipitation has been used for a variety of hydrological and paleoclimate studies, a starting point for which is the behaviour of stable isotopes in modern precipitation. To this end, daily precipitation samples were collected over a 7‐year period (2008–2014) at a semi‐arid site located at the Macquarie Marshes, New South Wales (Australia). The samples were analysed for stable isotope composition, and factors affecting the isotopic variability were investigated. The best correlation between δ18O of precipitation was with local surface relative humidity. The reduced major axis precipitation weighted local meteoric water line was δ2H = 7.20 δ18O + 9.1. The lower slope and intercept (when compared with the Global Meteoric Water Line) are typical for a warm dry climate, where subcloud evaporation of raindrops is experienced. A previously published model to estimate the degree of subcloud evaporation and the subsequent isotopic modification of raindrops was enhanced to include the vertical temperature and humidity profile. The modelled results for raindrops of 1.0 mm radius showed that on average, the measured D‐excess (=δ2H − 8 δ18O) was 19.8‰ lower than that at the base of the cloud, and 18% of the moisture was evaporated before ground level (smaller effects were modelled for larger raindrops). After estimating the isotopic signature at the base of the cloud, a number of data points still plotted below the global meteoric water line, suggesting that some of the moisture was sourced from previously evaporated water. Back trajectory analysis estimated that 38% of the moisture was sourced over land. Precipitation samples for which a larger proportion of the moisture was sourced over land were 18O and 2H‐enriched in comparison to samples for which the majority of the moisture was sourced over the ocean. The most common weather systems resulting in precipitation were inland trough systems; however, only East Coast Lows contributed to a significant difference in the isotopic values. Copyright © 2016 Australian Nuclear Science and Technology Organisation. Hydrological Processes. © 2016 John Wiley & Sons, Ltd.en_AU
dc.identifier.citationCrawford, J., Hollins, S. E., Meredith, K. T., & Hughes, C. E. (2017). Precipitation stable isotope variability and subcloud evaporation processes in a semi-arid region. Hydrological Processes, 31(1), 20-34. doi:10.1002/hyp.10885en_AU
dc.identifier.issn2150-3435en_AU
dc.identifier.issue1en_AU
dc.identifier.journaltitleHydrological Processesen_AU
dc.identifier.pagination20-34en_AU
dc.identifier.urihttps://doi.org/10.1002/hyp.10885en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/10482en_AU
dc.identifier.volume31en_AU
dc.language.isoenen_AU
dc.publisherJohn Wiley & Sons, Incen_AU
dc.subjectStable isotopesen_AU
dc.subjectPrecipitationen_AU
dc.subjectNew South Walesen_AU
dc.subjectAustraliaen_AU
dc.subjectArid landsen_AU
dc.subjectHumidityen_AU
dc.subjectEvaporationen_AU
dc.subjectGround wateren_AU
dc.subjectMoistureen_AU
dc.titlePrecipitation stable isotope variability and subcloud evaporation processes in a semi‐arid regionen_AU
dc.typeJournal Articleen_AU
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