Contrasting Seasonal Isotopic Signatures of Near-Surface Atmospheric Water Vapor in the Central Arctic During the MOSAiC Campaign

Autor(en)

C. F. Brunello, H. Meyer, M. Mellat, M. Casado, S. Bucci, M. Dütsch, M. Werner

Abstrakt

The Arctic is experiencing unprecedented moistening which is expected to have far-reaching impact on global climate and weather patterns. However, it remains unclear whether this newly sourced moisture originates locally from ice-free ocean regions or is advected from lower latitudes. In this study, we use water vapor isotope measurements in combination with trajectory-based diagnostics and an isotope-enabled atmosphere general circulation model, to assess seasonal shifts in moisture sources and transport pathways in the Arctic. Continuous measurements of near-surface vapor, δ¹⁸O, and δD were performed onboard RV Polarstern during the Multidisciplinary drifting Observatory for the Study of Arctic Climate expedition from October 2019 to September 2020. Combining this isotope data set with meteorological observations reveals that the spatiotemporal evolution of δ¹⁸O mimics changes in local temperature and humidity at synoptic to seasonal time scales, while corresponding d-excess changes suggest a seasonal shift in the origin of moisture. Simulation results from the particle dispersion model FLEXPART support these findings, indicating that summer moisture originates from nearby open ocean, while winter moisture comes from more remote sources with longer residence time over sea-ice. Results from a nudged ECHAM6-wiso simulation also indicate that evaporative processes from the ocean surface reproduce summer isotope values, but are insufficient to explain measured winter isotope values. Our study provides the first isotopic characterization of Central Arctic moisture over the course of an entire year, helping to differentiate the influence of local processes versus large-scale vapor transport on Arctic moistening. Future process-based investigations should focus on assessing the non-equilibrium isotopic fractionation during airmass transformation over sea-ice.

Organisation(en)

Institut für Meteorologie und Geophysik

Externe Organisation(en)

Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Université de Versailles-Saint-Quentin-en-Yvelines

Journal

Journal of Geophysical Research: Atmospheres

Band

128

ISSN

2169-897X

DOI

https://doi.org/10.1029/2022JD038400

Publikationsdatum

12-2023

Peer-reviewed

Ja

ÖFOS 2012

105204 Klimatologie

Schlagwörter

ASJC Scopus Sachgebiete

Geophysics, Atmospheric Science, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous)

Sustainable Development Goals

SDG 13 – Maßnahmen zum Klimaschutz

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/64f00078-5fe3-4d75-8890-eae32a2266fc