Submitted as: model description paper 24 Nov 2021

Submitted as: model description paper | 24 Nov 2021

Review status: this preprint is currently under review for the journal GMD.

GNOM v1.0: An optimized steady-state model of the modern marine neodymium cycle

Benoît Pasquier1, Sophia K. V. Hines2,3, Hengdi Liang1, Yingzhe Wu2, Seth G. John1, and Steven L. Goldstein2,4 Benoît Pasquier et al.
  • 1Earth Sciences Department, University of Southern California, Los Angeles, CA, USA
  • 2Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, USA
  • 3Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
  • 4Department of Earth and Environmental Sciences, Columbia University, Palisades, NY, USA

Abstract. Spatially distant sources of neodymium (Nd) to the ocean that carry different isotopic signatures (εNd) have been shown to trace out major water masses, and have thus been extensively used to study large-scale features of the ocean circulation both past and current. While the global marine Nd cycle is qualitatively well understood, a complete quantitative determination of all its components and mechanisms, such as the magnitude of its sources and the paradoxical conservative behavior of εNd, remains elusive. To make sense of the increasing collection of observational Nd and εNd data, we develop the global neodymium ocean model (GNOM) v1, the first inverse model of the global marine biogeochemical cycle of Nd. The GNOM is embedded in a data-constrained steady-state circulation that affords spectacular computational efficiency, which we leverage to estimate biogeochemical parameters via systematic objective optimization. Owing to its matrix representation, the GNOM model is additionally amenable to novel diagnostics that allow us to investigate open questions about the Nd cycle with unprecedented accuracy. The GNOM is open-source and freely accessible, is written in Julia, and its code is easily understandable and modifiable for further developments and experiments.

Benoît Pasquier et al.

Status: open (until 19 Jan 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Benoît Pasquier et al.

Benoît Pasquier et al.


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Short summary
Neodymium isotopes in seawater have the potential to provide key information about ocean circulation, both today and in the past. This can shed light on the underlying drivers of global climate, which will improve our ability to predict future climate change, but uncertainties in our understanding of neodymium cycling have limited use of this tracer. We present a new model of neodymium in the modern ocean that runs extremely fast, matches observations, and is freely available for development.