Report outlining a strategic approach for efficiency savings based on concurrency and accuracy (D2.6)

Earth System Models typically comprise a number of component models such as an atmospheric model, ocean model, ice model and a chemistry model. These execute as separate executables or as a single
executable and exchange data using a coupler. The coupler controls the execution and time evolution of the complete system by synchronising and controlling the flow of data between the various components. In this work we explore the use of OpenMP to run model components  concurrently within a single executable. The model components supported here are the ECMWF radiation and wave models.
To run concurrently with the rest of the IFS forecast model, it is necessary that these components run lagged by one radiation time‐step and one model time‐step respectively. The objective is to improve the
computational performance beyond what is achieved today whether component models are run sequentially or concurrently using a single executable or separate executables.