Anne-Marie Wefing


Last Name

Wefing

First Name

Anne-Marie

ORCID

0000-0001-6855-6062

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2018 - 201952020 - 202514
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Publications 1 - 10 of 19
  • Long-lived radionuclides (129I and 236U) as water mass tracers in the North Atlantic and Fram Strait
    Item type: Other Conference Item
    Wefing, Anne-Marie; Castrillejo, Maxi; Casacuberta, Núria; et al. (2019)
    Geophysical Research Abstracts
  • Anthropogenic Carbon in the Arctic Ocean: Perspectives From Different Transient Tracers
    Item type: Journal Article
    Raimondi, Lorenza; Wefing, Anne-Marie; Casacuberta, Núria (2024)
    Journal of Geophysical Research: Oceans
    In this study we investigated the physical characteristics of the Atlantic layer in the Arctic Ocean (AO) and its role in the distribution and storage of anthropogenic carbon (Cant). The novelty of this work is to use the Transit Time Distribution method (TTD) with the radionuclides 129I and 236U and its comparison to the commonly applied gas tracers, CFC-12 and SF6. Overall, our examination of two distinct tracer pairs, along with the novel TTD method in comparison to a classical approach, revealed a notable agreement, highlighting the robustness of these Cant estimates. The TTD analysis based on radionuclides showed that whereas the Eurasian Basin has shorter transit times and is dominated by strong mixing conditions, the Amerasian Basin is characterized by longer transit times and a strong advective flow. Overall, the Cant concentrations obtained from radionuclides confirm that the distribution in the AO follows its circulation patterns, with higher concentrations in the Eurasian Basin (∼50 μmol kg−1) compared to the Amerasian one (∼36–42 μmol kg−1). An estimated partial inventory of 0.85 ± 0.17 and 1.0 ± 0.03 Pg C was assessed for 2015 from the novel application of TTD with radionuclides and gas tracers, respectively. Finally, we identified the saturation of gas tracers as a larger source of uncertainty for Cant estimation compared to the uncertainty associated to different radionuclides' input functions, thus remarking the importance of including non-saturation dependent tracers, such as radionuclides, as an additional tool to support Cant estimates in the AO.
  • Hafnium-Neodymium isotope compositions to trace freshwater inputs to Beaufort Gyre
    Item type: Other Conference Item
    Casacuberta, Núria; Payne, Annabel; Zimmerman, Sarah; et al. (2024)
    Ocean Sciences Meeting 2024 Online Program
  • A multi-tracer approach to better understand circulation and anthropogenic carbon storage: a 2015 study in the Arctic Ocean
    Item type: Other Conference Item
    Raimondi, Lorenza; Wefing, Anne-Marie; Casacuberta, Núria (2024)
    Ocean Sciences Meeting 2024 Online Program
  • 129I and 236U Transit Time Distributions of Atlantic Waters in the Arctic Ocean and Fram Strait
    Item type: Other Conference Item
    Wefing, Anne-Marie; Casacuberta, Núria; Christl, Marcus; et al. (2019)
    Online Abstracts: Goldschmidt 2019
  • CT14B-1285:129I and 236U as Tracers of Water Mass Circulation in the Fram Strait
    Item type: Conference Poster
    Wefing, Anne-Marie; Casacuberta, Núria; Christl, Marcus; et al. (2018)
    Book of Abstracts of the 2018 Ocean Sciences Meeting
  • Circulation timescales and mixing in the Fram Strait (2016 - 2021): Perspectives from transient radionuclide tracers
    Item type: Other Conference Item
    Scheiwiller, Marcel; Wefing, Anne-Marie; Vockenhuber, Christof; et al. (2024)
  • High Precision 14C Analysis in Small Seawater Samples
    Item type: Other Journal Item
    Casacuberta, Núria; Castrillejo, Maxi; Wefing, Anne-Marie; et al. (2020)
    Radiocarbon
  • Water mass composition in Fram Strait determined from the combination of 129I and 236U: Changes between 2016, 2018, and 2019
    Item type: Journal Article
    Wefing, Anne-Marie; Casacuberta, Núria; Christl, Marcus; et al. (2022)
    Frontiers in Marine Science
    Changes in the provenance and composition of waters exported from the Arctic Ocean have the potential to impact large-scale ocean circulation processes in the sub-polar North Atlantic. The main conveyor of waters from the Arctic Ocean to lower latitudes is the East Greenland Current (EGC), flowing southward through Fram Strait. It is therefore crucial to determine and monitor the composition of the EGC, a mixture of polar waters of different origins. Here we present a pilot study on the potential of the long-lived anthropogenic radionuclides 129I and 236U as tracers of the EGC water mass composition, based on a time series of 236U and 129I concentrations measured across Fram Strait in the years 2016, 2018, and 2019. The overall spatial distribution of 236U and 129I was similar among the three sampling years, but a decrease in concentration was observed in the upper water column of the EGC. The observed changes could only partly be attributed to the transient nature of the radionuclide signals, but instead pointed to changes in the EGC water mass composition. To investigate these changes, 236U and 129I were first combined in a mixing model featuring the endmembers expected in the upper EGC. We distinguished between Pacific Water (PAC), Atlantic Water advected from the Arctic Ocean (ATL), and Atlantic Water recirculating in Fram Strait (RAC). In 236U-129I tracer space, PAC and RAC showed similar tracer signatures, but were well distinguished from ATL. From 2016 to 2018/19, a decrease in the ATL fraction was evident for the upper EGC. Secondly, the respective combination of 236U and 129I with salinity showed differences in absolute water mass fractions, but similar temporal trends. Both suggested an increase in PAC of about 20% for the uppermost layer of the EGC (samples with potential densities below 26.5) and an increase in RAC of about 10−20 % for denser samples. 129I and 236U, in combination with salinity, were shown to be suitable tracers to investigate water mass composition in Fram Strait, with the advantage that they can distinguish Atlantic Water advected from the Arctic Ocean from that recirculating in Fram Strait.
  • The long-lived anthropogenic radionuclides I-129 and U-236 as tracers of water mass provenance, circulation timescales and mixing in the Arctic Ocean and Fram Strait
    Item type: Other Conference Item
    Wefing, Anne-Marie; Casacuberta, Núria; Christl, Marcus; et al. (2020)
    EGUsphere
Publications 1 - 10 of 19