δ<sup>18</sup>O water isotope in the <i>i</i>LOVECLIM model (version 1.0) – Part 2: Evaluation of model results against observed δ<sup>18</sup>O in water samples

Abstract

Abstract. The H 2 18 O stable isotope was previously introduced in the three coupled components of the earth system model iLOVECLIM: atmosphere, ocean and vegetation. The results of a long (5000 yr) pre-industrial equilibrium simulation are presented and evaluated against measurement of H 2 18 O abundance in present-day water for the atmospheric and oceanic components. For the atmosphere, it is found that the model reproduces the observed spatial distribution and relationships to climate variables with some merit, though limitations following our approach are highlighted. Indeed, we obtain the main gradients with a robust representation of the Rayleigh distillation but caveats appear in Antarctica and around the Mediterranean region due to model limitation. For the oceanic component, the agreement between the modelled and observed distribution of water δ 18 O is found to be very good. Mean ocean surface latitudinal gradients are faithfully reproduced as well as the mark of the main intermediate and deep water masses. This opens large prospects for the applications in palaeoclimatic context.

Glacial–interglacial changes in H<sub>2</sub><sup>18</sup>O, HDO and deuterium excess – results from the fully coupled ECHAM5/MPI-OM Earth system model

“…3500 m, depleted AABW (δ 18 O oce between −0.4 and −0.1 ‰) fills the entire Pacific. The overall pattern of the Atlantic and Pacific cross sections is in good agreement with a recent study of the iLOVECLIM isotope-enabled EMIC (Roche and Caley, 2013) as well as with two ocean-only GCM studies (Paul et al, 1999;.…”

“…As a second fully coupled GCM, the HadCM3 model has been enhanced by a stable water isotope diagnostics module by Tindall et al (2009) for analyses of the present-day isotopic signature of El Niño-Southern Oscillation and the tropical amount effect. Besides these two fully coupled isotope-enabled GCMs, there have also been some efforts in including water stable isotopes in the hydrological cycle of Earth system models of intermediate complexity (EMICs) by Roche et al (2004), Brennan et al (2012), as well as Roche and Caley (2013). These isotopeenabled EMICs can be classified as an alternative tool to test ideas, explore large periods of time in a transient mode, and guide much more computationally demanding simulations with fully coupled GCMs.…”

Stable water isotopes in the MITgcm

“…Despite these sources of error, the simulated pattern of δ 18 O w both at the sea surface as well as in the deep ocean agrees fairly well with other recent studies such as the study by Xu et al (2012) with an OGCM as well as the studies by Roche and Caley (2013) and Werner et al (2016) with fully coupled models.…”

A Dynamical Reconstruction of the Global Monthly Mean Oxygen Isotopic Composition of Seawater

“…Simulations of other water isotope‐enabled ocean‐only and coupled atmosphere‐ocean models deviate from the observational data typically in the enriched areas of the subtropics, in the northern part of the Indian ocean, and/or in the isotopically depleted Arctic Ocean (e.g., Delaygue et al, ; Roche & Caley, ; Werner et al, ). A comparatively good agreement with the observational data is shown in the ocean‐only model simulations by Xu et al (), who prescribe the isotopic composition of precipitation and evaporation and used a salinity restoring, or by Paul et al (), who prescribed a surface field as boundary condition.…”