Moisture origin as a driver of temporal variabilities of the water vapour isotopic composition in the Lena River Delta, Siberia


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jlbonne [ at ] crans.org

Abstract

In the context of the Arctic amplification of climate change affecting the regional atmospheric hydrological cycle, it is crucial to characterize the present-day moisture sources of the Arctic. The isotopic composition is an important tool to enhance our understanding of the drivers of the hydrological cycle due to the different molecular characteristics of water stable isotopes during phase change. This study introduces 2 years of continuous in situ water vapour and precipitation isotopic observations conducted since July 2015 in the eastern Siberian Lena delta at the research station on Samoylov Island. The vapour isotopic signals are dominated by variations at seasonal and synoptic timescales. Diurnal variations of the vapour isotopic signals are masked by synoptic variations, indicating low variations of the amplitude of local sources at the diurnal scale in winter, summer and autumn. Low-amplitude diurnal variations in spring may indicate exchange of moisture between the atmosphere and the snow-covered surface. Moisture source diagnostics based on semi-Lagrangian backward trajectories reveal that different air mass origins have contrasting contributions to the moisture budget of the Lena delta region. At the seasonal scale, the distance from the net moisture sources to the arrival site strongly varies. During the coldest months, no contribution from local secondary evaporation is observed. Variations of the vapour isotopic composition during the cold season on the synoptic timescale are strongly related to moisture source regions and variations in atmospheric transport: warm and isotopically enriched moist air is linked to fast transport from the Atlantic sector, while dry and cold air with isotopically depleted moisture is generally associated with air masses moving slowly over northern Eurasia.



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ISI/Scopus peer-reviewed
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Published
Eprint ID
52948
DOI 10.5194/acp-20-10493-2020

Cite as
Bonne, J. L. , Meyer, H. , Behrens, M. , Boike, J. , Kipfstuhl, S. , Rabe, B. , Schmidt, T. , Schönicke, L. , Steen-Larsen, H. C. and Werner, M. , Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, 27515 Bremerhaven, Germany, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, 14401 Potsdam, Germany, Geography Department, Humboldt-Universität zu Berlin, 10099 Berlin, Germany, Geophysical Institute, University of Bergen, 5020 Bergen, Norway, Bjerknes Centre for Climate Research, 5020 Bergen, Norway (2020): Moisture origin as a driver of temporal variabilities of the water vapour isotopic composition in the Lena River Delta, Siberia , Atmospheric Chemistry and Physics, 20 (17), pp. 10493-10511 . doi: 10.5194/acp-20-10493-2020


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