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A precipitation isotopic response in 2014-2015 to moisture transport changes in the central Himalayas
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  • Josefine Axelsson,
  • Jing Gao,
  • Sabine Eckhardt,
  • Massimo Cassiani,
  • Deliang Chen,
  • Qiong Zhang
Josefine Axelsson
Department of Physical Geography and Bolin Centre for Climate Research, Stockholm University

Corresponding Author:josefine.axelsson@natgeo.su.se

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Jing Gao
Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, CAS
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Sabine Eckhardt
NILU Norwegian Institute for Air Research
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Massimo Cassiani
Norwegian Institute for Air Research (NILU)
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Deliang Chen
University of Gothenburg
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Qiong Zhang
Department of Physical Geography and Bolin Centre for Climate Research, Stockholm University
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The effect of moisture transport on precipitation stable isotopes (δ18O and d-excess) in the central Himalayas is still unclear, although crucial to understand the climatic archives recorded in, e.g., ice cores. Here we present measurements of stable isotopes in precipitation at two stations (Yadong and Pali) in the central Himalayas during 2014-2015. Combined with simulations from the dispersion model FLEXPART, we investigate possible effects on precipitation stable isotopes related to changes in moisture sources and convections in the region. Here we show that precipitation stable isotopes and convective activities are different between 2014 and the El Niño year 2015 in Yadong Valley. Our results show that enriched 18O and high d-excess in precipitation during the 2015 monsoon season compared to 2014 is accompanied by a change in δ18O lapse rate as an outcome of changes in upstream convection which alters δ18O through kinetic fractionation. During 2015, isotopic variations are linked to larger contributions of moisture from the Arabian Sea and the Indian continent, as well as lesser from the Bay of Bengal (BoB). Outgoing longwave radiation and moisture flux divergence analysis further confirms that contribution from continental evaporation dominates the moisture supply in the central Himalayas with a lesser contribution from convection over the BoB during the 2015 monsoon season, compared with 2014. These findings provide insights into climatic interpretations of paleo-isotopic archives regarding responses to changes in moisture transport to the central Himalayas.
29 Jan 2023Submitted to ESS Open Archive
01 Feb 2023Published in ESS Open Archive