Annabel Payne


Last Name

Payne

First Name

Annabel

ORCID

0000-0001-9523-0316

Organisational unit

09755 - Casacuberta Arola, Núria / Casacuberta Arola, Núria

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2022 - 20255
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Publications 1 - 5 of 5
  • 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
  • Circulation Timescales and Pathways of Atlantic Water in the Canada Basin: Insights From Transient Tracers ¹²⁹I and ²³⁶U
    Item type: Journal Article
    Payne, Annabel; Wefing, Anne-Marie; Christl, Marcus; et al. (2024)
    Journal of Geophysical Research: Oceans
    Anthropogenic radionuclides 129I and 236U are used to investigate pathways of the Atlantic Water flow in the Canada Basin, estimate transport timescales, and investigate mixing dynamics within the Atlantic Water layer and the overlying Pacific Water. Transit Time Distribution (TTD) model mean ages indicate water takes 25–35 years to reach the Canada Basin from the entrance of the Arctic, with limited lateral and vertical mixing along the core of the Arctic Ocean Boundary Current. Mode ages obtained from the model yield shorter transport times of 20–32 years. These age estimates agree with previous studies using these radionuclides and ventilation tracers in this region, indicating a steady-state flow of Atlantic Water for the last 15 years. The distribution of the isotopes in the Atlantic layer indicates two pathways Atlantic Water may take into the basin, supported by the distribution of ages in the TTD model. End-member mixing models indicate that the Pacific Winter water acquires a 20%–40% Atlantic Water signal of the radionuclides, upwelled over short periods, most likely along the shelf and Barrow Canyon region.
  • Circulation timescales and pathways of Atlantic Waters in the Arctic Canada Basin using novel tracers Iodine-129 and Uranium-236
    Item type: Other Conference Item
    Casacuberta, Núria; Payne, Annabel; Schneuwly, Aline; et al. (2024)
    Ocean Sciences Meeting 2024 Online Program
  • Widespread lithogenic control of marine authigenic neodymium isotope records? Implications for paleoceanographic reconstructions
    Item type: Journal Article
    Abbott, April N.; Löhr, Stefan C.; Payne, Annabel; et al. (2022)
    Geochimica et Cosmochimica Acta
    Our understanding of past ocean-climate dynamics is informed by multiple paleocirculation proxies including δ13C, 231Pa/230Th, and radiogenic neodymium isotopes (εNd). Of these, the εNd signature of marine authigenic phases is of particular importance as it is considered a robust circulation proxy applicable across timescales, permitting circulation reconstructions during periods of rapid, climatically-induced biological or chemical change (e.g. productivity, pH). However, growing evidence of non-conservative behavior and a widespread sedimentary source (benthic flux via pore water) of Nd to the global ocean suggests that authigenic εNd records do not strictly record a water mass signature, highlighting the need to reconsider interpretations of the authigenic record. To examine the impact of a sedimentary influence on the authigenic record, here we compile paired authigenic and detrital neodymium records from every major ocean basin and from 80 Ma to present. We then focus on just the North Atlantic Ocean basin to examine if this relationship holds up regionally and how authigenic εNd changes relate to sediment composition changes from two scientific ocean drill cores spanning the past 25 ka. We present a new conceptual framework to guide our discussion that examines the coupling or decoupling of authigenic and detrital εNd in terms of the relative importance of each of the three major potential controls as defined in the existing literature (bottom water, pore water, sediments) on the authigenic record. Our compilation reveals a strong linear relationship between detrital εNd and authigenic εNd (correlation coefficient = 0.86, n = 871), demonstrating a widespread influence of lithogenically sourced neodymium on authigenic εNd. We find the same is true within the North Atlantic, with the authigenic records at both locations strongly influenced by the sediments and likely not recording bottom water neodymium values. Emerging evidence for a lithogenic or benthic flux influence on the budgets of a wide range of trace elements suggests that our interpretative framework will be broadly useful for understanding the behavior of trace elements and their isotopes at the sediment-water interface.
  • Changes in water mass composition and circulation in the central Arctic Ocean between 2011 and 2021 inferred from tracer observations
    Item type: Journal Article
    Wefing, Anne-Marie; Payne, Annabel; Vockenhuber, Christof; et al. (2025)
    Ocean Science
    The Arctic Ocean is changing rapidly and Atlantic Water circulation plays a key role in the warming, sea-ice decline, and ecosystem changes observed in the Arctic. Still, we only have limited understanding of the pathways and circulation times of Atlantic-derived water both at surface and mid-depth layers in the Arctic Ocean, and their evolution over time. Here, we investigate the water mass composition and circulation in the central Arctic Ocean in 2021 and assess temporal changes thereof between 2011 and 2021 by using the long-lived anthropogenic radionuclides ¹²⁹I and ²³⁶U. This study is based on radionuclide data collected in the central Arctic Ocean and for the first time north of Greenland as part of one of the ocean expeditions of the Synoptic Arctic Survey (SAS-Oden 2021), and available historic data across the Arctic Ocean between 2011 and 2021. We obtain tracer ages as well as the mixing of different endmembers in the surface layer using a tracer-based mixing model. Atlantic Water circulation times and mixing in the mid-depth Atlantic layer are obtained from the Transit Time Distribution (TTD) model. For 2021, we find a sharp decrease in surface ¹²⁹I and ²³⁶U concentrations between the Amundsen and Makarov Basins, pointing to substantial fractions of Pacific Water reaching the Lomonosov Ridge from the Amerasian side. In the halocline layer, similar ¹²⁹I and ²³⁶U concentrations on both sides of the Lomonosov Ridge suggest a common formation region of halocline waters with a clear Atlantic Water signal. North of Greenland, we find a mixture of waters that originate from the Canada and Amundsen Basins, both in the surface and the mid-depth layer. Circulation times of Atlantic Water in the mid-depth layer point to a longer transport route on the Makarov Basin side of the Lomonosov Ridge compared to the Amundsen Basin. When looking at the temporal variability between 2011 and 2021, we observe a shift of the Atlantic-Pacific Water front from the Makarov Basin towards the Lomonosov Ridge from 2011/2012 to 2015 and 2021. In the mid-depth Atlantic layer, we find an increase in mean and mode ages from 2015 to 2021, suggesting a slowdown or changes in the pathways of the Arctic Ocean Boundary Current, which is in line with recent studies based on gas tracers.
Publications 1 - 5 of 5