Modeling Neodymium Isotopes in the Ocean Component of the CESM1

Neodymium (Nd) isotopic composition ( ε Nd ) is an important tracer for water mass mixing and the reconstruction of past ocean circulation. To allow for a direct model ‐ data comparison, we have implemented Nd isotopes in the ocean component of the Community Earth System Model (CESM1.3). The model is able to capture the major features of the observed modern distribution of both ε Nd and Nd concentrations. Our model provides a useful tool for the interpretation of ε Nd reconstructions. For example, we show that in an idealized North Atlantic freshwater hosing experiment, ε Nd changes in the Atlantic are documenting primarily the changes in water mass mixing and are hardly affected by the concomitant and large changes in the marine biological productivity and organic matter fl uxes. However, the hosing experiment also shows that the end ‐ member changes due to the change of ocean circulation can in fl uence the interpretation of ε Nd in the Atlantic, depending on the location. The implementation of Nd, together with other existing tracers, such as δ 18 O, 231 Pa/ 230 Th, δ 13 C, and radiocarbon in the same model, can improve our understanding of past ocean circulation signi fi cantly. reconstructions measures proxy records and climate model simulate physical variables, both of which have uncertainties and it is hard to address the model data discrepancies. To meet this challenge, we implement the Nd isotopes, which is more and more used in paleoceanography, in the ocean component of the Community Earth System Model (CESM). Our model is able to simulate ε Nd in good agreement with observations. With other isotopes, such as δ 18 O, 231 Pa/ 230 Th, δ 13 C, and radiocarbon in the same model, this isotope ‐ enabled CESM provides a powerful tool to improve the understanding of past ocean circulation changes. Furthermore, the hosing experiment suggests that the interpretation of ε Nd changes in the Atlantic as changes in the water mass mixing can be complicated by the changes in the end ‐ member values in some locations.

[1]  Zhengyu Liu,et al.  231 Pa and 230 Th in the ocean model of the Community Earth System Model (CESM1.3) , 2017 .

[2]  F. Joos,et al.  Coherent response of Antarctic Intermediate Water and Atlantic Meridional Overturning Circulation during the last deglaciation: reconciling contrasting neodymium isotope reconstructions from the tropical Atlantic , 2017 .

[3]  F. Joos,et al.  New insights into cycling of 231Pa and 230Th in the Atlantic Ocean , 2017 .

[4]  T. van de Flierdt,et al.  Neodymium in the oceans: a global database, a regional comparison and implications for palaeoceanographic research , 2016, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[5]  A. Piotrowski,et al.  Abyssal origin for the early Holocene pulse of unradiogenic neodymium isotopes in Atlantic seawater , 2016 .

[6]  C. Jeandel,et al.  Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary , 2015, Nature Communications.

[7]  S. B. Moran,et al.  Intensity of Th and Pa scavenging partitioned by particle chemistry in the North Atlantic Ocean , 2015 .

[8]  A. Osborne,et al.  Neodymium isotopes and concentrations in Caribbean seawater: Tracing water mass mixing and continental input in a semi-enclosed ocean basin , 2014 .

[9]  K. Lindsay,et al.  Carbon isotopes in the ocean model of the Community Earth System Model (CESM1) , 2014 .

[10]  Alexander L. Thomas,et al.  Controls on seawater 231Pa, 230Th and 232Th concentrations along the flow paths of deep waters in the Southwest Atlantic , 2014 .

[11]  D. Oppo,et al.  Decreased influence of Antarctic intermediate water in the tropical Atlantic during North Atlantic cold events , 2014 .

[12]  W. Collins,et al.  The Community Earth System Model: A Framework for Collaborative Research , 2013 .

[13]  A. Galy,et al.  Reconstructing deglacial North and South Atlantic deep water sourcing using foraminiferal Nd isotopes , 2012 .

[14]  F. Joos,et al.  Sensitivity of Nd isotopic composition in seawater to changes in Nd sources and paleoceanographic implications , 2012 .

[15]  F. Joos,et al.  On the relationship between Nd isotopic composition and ocean overturning circulation in idealized freshwater discharge events , 2012 .

[16]  C. Jeandel,et al.  Neodymium isotopic composition of the oceans: A compilation of seawater data , 2012 .

[17]  S. Bates,et al.  The CCSM4 Ocean Component , 2012 .

[18]  M. Frank,et al.  The hafnium and neodymium isotope composition of seawater in the Atlantic sector of the Southern Ocean , 2012 .

[19]  F. Joos,et al.  Modelling Nd-isotopes with a coarse resolution ocean circulation model: Sensitivities to model parameters and source/sink distributions , 2011 .

[20]  D. Richards,et al.  Persistent Nordic deep-water overflow to the glacial North Atlantic , 2011 .

[21]  J. McManus,et al.  Synchronous Deglacial Overturning and Water Mass Source Changes , 2010, Science.

[22]  C. Jeandel,et al.  Reconstructing the Nd oceanic cycle using a coupled dynamical – biogeochemical model , 2009 .

[23]  M. Ebihara,et al.  Nd isotopic composition in the central North Pacific , 2009 .

[24]  Stephen G. Yeager,et al.  The global climatology of an interannually varying air–sea flux data set , 2009 .

[25]  L. Bopp,et al.  Influence of particle size and type on 231Pa and 230Th simulation with a global coupled biogeochemical‐ocean general circulation model: A first approach , 2009 .

[26]  S. Goldstein,et al.  Abrupt changes in Antarctic Intermediate Water circulation over the past 25,000 years , 2008 .

[27]  M. Siddall,et al.  Towards explaining the Nd paradox using reversible scavenging in an ocean general circulation model , 2008 .

[28]  M. Kageyama,et al.  A modeling sensitivity study of the influence of the Atlantic meridional overturning circulation on neodymium isotopic composition at the Last Glacial Maximum , 2008 .

[29]  S. Goldstein,et al.  Modeling the distribution of Nd isotopes in the oceans using an ocean general circulation model , 2008 .

[30]  C. Jeandel,et al.  Modeling the neodymium isotopic composition with a global ocean circulation model , 2007 .

[31]  C. Jeandel,et al.  Isotopic Nd compositions and concentrations of the lithogenic inputs into the ocean: A compilation, with an emphasis on the margins , 2007 .

[32]  F. Joos,et al.  231Pa/230Th fractionation by ocean transport, biogenic particle flux and particle type , 2005 .

[33]  A. Schmittner.  Decline of the marine ecosystem caused by a reduction in the Atlantic overturning circulation , 2005, Nature.

[34]  J. Hein,et al.  New constraints on the sources and behavior of neodymium and hafnium in seawater from Pacific Ocean ferromanganese crusts , 2004 .

[35]  Steven L. Goldstein,et al.  Intensification and variability of ocean thermohaline circulation through the last deglaciation , 2004 .

[36]  S. Goldstein,et al.  Long-lived Isotopic Tracers in Oceanography, Paleoceanography, and Ice-sheet Dynamics , 2003 .

[37]  N. Mahowald,et al.  Sensitivity study of meteorological parameters on mineral aerosol mobilization, transport, and distribution , 2003 .

[38]  C. Jeandel,et al.  Neodymium budget in the modern ocean and paleo‐oceanographic implications , 2003 .

[39]  I. Kriest.  Different parameterizations of marine snow in a 1D-model and their influence on representation of marine snow, nitrogen budget and sedimentation , 2002 .

[40]  Gian-Kasper Plattner,et al.  Feedback mechanisms and sensitivities of ocean carbon uptake under global warming , 2001 .

[41]  F. Blanckenburg.  Tracing Past Ocean Circulation , 1999 .

[42]  C. Heinze,et al.  Global distribution of the 230Th flux to ocean sediments constrained by GCM modelling , 1999 .

[43]  E. Jansen,et al.  Rapid changes in the mechanism of ocean convection during the last glacial period , 1999, Nature.

[44]  P. Statham,et al.  Rare earth element mobilization from marine atmospheric dust into seawater , 1994 .

[45]  C. Jeandel.  Concentration and isotopic composition of Nd in the South Atlantic Ocean , 1993 .

[46]  H. Elderfield,et al.  The geochemical balance of the rare earth elements and neodymium isotopes in the oceans , 1993 .

[47]  Francis E. Grousset,et al.  Neodymium isotopes as tracers in marine sediments and aerosols: North Atlantic , 1988 .

[48]  S. J. Goldstein,et al.  The Nd and Sr isotopic systematics of river-water dissolved material: Implications for the sources of Nd and Sr in seawater , 1987 .

[49]  G. Wasserburg,et al.  Rare earth element transport in the western North Atlantic inferred from Nd isotopic observations , 1987 .

[50]  S. Goldstein,et al.  A Sm-Nd isotopic study of atmospheric dusts and particulates from major river systems , 1984 .

[51]  R. Anderson,et al.  Distribution of thorium isotopes between dissolved and particulate forms in the deep sea , 1982 .

[52]  G. Wasserburg,et al.  Sm-Nd isotopic evolution of chondrites , 1980 .

[53]  Y. Hisaki.  Deep Sea Research Part I: Oceanographic Research Papers , 2019 .

[54]  A. Bory,et al.  SAHARAN WIND REGIMES TRACED BY THE Sr–Nd ISOTOPIC COMPOSITION OF SUBTROPICAL ATLANTIC SEDIMENTS: LAST GLACIAL MAXIMUM vs TODAY , 1998 .

[55]  J. Duplessy,et al.  Changes in the vertical structure of the North Atlantic Ocean between glacial and modern times , 1992 .