A global scavenging and circulation ocean model of thorium-230 and protactinium-231 with realistic particle dynamics (NEMO–ProThorP 0.1)

Abstract

Abstract. In this paper, we set forth a 3-D ocean model of the radioactive trace isotopes Future model development may further improve understanding, especially when this will include a more complete represen-15 tation of all particles, including different size classes, manganese hydroxides and nepheloid layers. This can be done based on our model, as its source code is readily available.

230Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

“…Now, most 3-D models consider at least three different biogenic particle types: calcium carbonate (CaCO 3 ), particulate organic carbon, and opal. Some models also include lithogenic (dust and fluvial) particles (Siddall et al, 2005;Van Hulten et al, 2018) or other aerosols like volcanic ash (Rogan et al, 2016), but uncertainty regarding their influence on Th scavenging has justified their omission in other models (e.g., Gu & Liu, 2017;Missiaen et al, 2019). At the same time, all models face challenges in reproducing the observed particle size spectrum.…”

“…HAMOCC (Heinze et al, 2018) is the only model currently updated with the newer scavenging coefficients from the Atlantic GEOTRACES section (Hayes, Anderson, Fleisher, Huang, et al, 2015). In NEMO-PISCES (Dutay et al, 2009;Van Hulten et al, 2018) and iLOVECLIM (Missiaen et al, 2019), the 230 Th scavenging coefficients are scaled to the particle fluxes rather than based on data from either JGOFS or GEOTRACES.…”

“…In this section we compare the preindustrial outputs of two GCMs (Figure 3), NEMO-PISCES (Dutay et al, 2009;Van Hulten et al, 2018) and Community Earth System Model (CESM) (Gu & Liu, 2017), and two models of intermediate complexity, iLOVECLIM (Missiaen et al, 2019) and HAMOCC (Heinze et al, 2006(Heinze et al, , 2018. We evaluate the 230 Th flux to the sediments (F) normalized by the production of 230 Th in the overlying water column (P).…”

“…(c) CESM(Gu & Liu, 2017). (d) NEMO-PISCES(Dutay et al, 2009;Van Hulten et al, 2018). Overlain circles show flux to production (F/P) ratios measured at bottom-moored sediment traps(Chase et al, 2003;Lyle et al, 2014;Scholten et al, 2005;Yu et al, 2001).…”

230Th normalization: New insights on an essential tool for quantifying sedimentary fluxes in the modern and Quaternary ocean

“…To explain complex (nonlinear) 230 Th profiles, more elaborate box models were developed that could account for different transport conditions and particle regimes under different ocean conditions, such as upwelling of deep water masses in the Southern Ocean (Chase et al, 2003;Roy-Barman et al, 2019;Rutgers van der Loeff et al, 2016;Rutgers van der Loeff & Berger, 1993;Venchiarutti et al, 2011), convection of deep water masses in the North Atlantic (Moran et al, 1995(Moran et al, , 1997Vogler et al, 1998), and lateral exchange between open ocean and ocean margin regimes (Anderson et al, 1983;Roy-Barman et al, 2009). More recently, 230 Th has also been integrated into complex geographic schemes in 2-D models (Luo et al, 2010;Marchal et al, 2000), in 3-D models of intermediate complexity (Henderson et al, 1999;Missiaen et al, 2019;Rempfer et al, 2017;Siddall et al, 2007Siddall et al, , 2005, and in global climate models (GCMs) (Dutay et al, 2009;Gu & Liu, 2017;Rogan et al, 2016;Van Hulten et al, 2018). The models of intermediate complexity are generally computationally efficient (i.e., able to produce 1,000 years of simulations in a few hours), but their spatial resolution is rather coarse (e.g., Henderson et al, 1999;Siddall et al, 2005) and/or the particle representation contains strong simplifications (e.g., Missiaen et al, 10.1029/2019PA003820…”