Publications des scientifiques de l'IRD

Séférian R., Gehlen M., Bopp L., Resplandy L., Orr J. C., Marti O., Dunne J. P., Christian J. R., Doney S. C., Ilyina T., Lindsay K., Halloran P. R., Heinze C., Segschneider J., Tjiputra J., Aumont Olivier, Romanou A. (2016). Inconsistent strategies to spin up models in CMIP5 : implications for ocean biogeochemical model performance assessment. Geoscientific Model Development, 9 (5), p. 1827-1851. ISSN 1991-959X.

Titre du document
Inconsistent strategies to spin up models in CMIP5 : implications for ocean biogeochemical model performance assessment
Année de publication
2016
Type de document
Article référencé dans le Web of Science WOS:000376937800008
Auteurs
Séférian R., Gehlen M., Bopp L., Resplandy L., Orr J. C., Marti O., Dunne J. P., Christian J. R., Doney S. C., Ilyina T., Lindsay K., Halloran P. R., Heinze C., Segschneider J., Tjiputra J., Aumont Olivier, Romanou A.
Source
Geoscientific Model Development, 2016, 9 (5), p. 1827-1851 ISSN 1991-959X
During the fifth phase of the Coupled Model Inter-comparison Project (CMIP5) substantial efforts were made to systematically assess the skill of Earth system models. One goal was to check how realistically representative marine biogeochemical tracer distributions could be reproduced by models. In routine assessments model historical hind-casts were compared with available modern biogeochemical observations. However, these assessments considered neither how close modeled biogeochemical reservoirs were to equilibrium nor the sensitivity of model performance to initial conditions or to the spin-up protocols. Here, we explore how the large diversity in spin-up protocols used for marine biogeochemistry in CMIP5 Earth system models (ESMs) contributes to model-to-model differences in the simulated fields. We take advantage of a 500-year spin-up simulation of IPSL-CM5A-LR to quantify the influence of the spin-up protocol on model ability to reproduce relevant data fields. Amplification of biases in selected biogeochemical fields (O-2, NO3, Alk-DIC) is assessed as a function of spin-up duration. We demonstrate that a relationship between spin-up duration and assessment metrics emerges from our model results and holds when confronted with a larger ensemble of CMIP5 models. This shows that drift has implications for performance assessment in addition to possibly aliasing estimates of climate change impact. Our study suggests that differences in spin-up protocols could explain a substantial part of model disparities, constituting a source of model-to-model uncertainty. This requires more attention in future model intercomparison exercises in order to provide quantitatively more correct ESM results on marine biogeochemistry and carbon cycle feedbacks.
Plan de classement
Sciences fondamentales / Techniques d'analyse et de recherche [020] ; Sciences du milieu [021] ; Limnologie physique / Océanographie physique [032] ; Ecologie, systèmes aquatiques [036]
Description Géographique
MONDE
Localisation
Fonds IRD [F B010066960]
Identifiant IRD
fdi:010066960
Contact