Driving NEMO Towards Exascale: Introduction of a New Software Layer in the NEMO Stack Software

This paper addresses scientific challenges related to high level implementation strategies that leads NEMO to effectively use of the opportunities of exascale systems. We consider two software modules as proof-of-concept: the Sea Surface Height equation solver and the Variational Data Assimilation system, which are components of the NEMO ocean model (OPA). Advantages rising from the introduction of consolidated scientific libraries in NEMO are highlighted: such advantages concern both the "software quality" improvement (see the software quality parameters like robustness, portability, resilence, etc.) and time reduction of software development