Computational Efficiency Of The Aerosol Scheme In The Met Office Unified Model

A new data structuring has been implemented which improves the performance of the aerosol subsystem in the UK Met Office Unified Model. Smaller amounts of atmospheric data, in the arrangement of segments of atmospheric columns, are handed to the aerosol sub-processes. The number of columns that are in a segment can be changed at runtime and is tuned to the hardware and science in operation. This revision alone has halved the time spent in some of the aerosol sections for the case under investigation. The new arrangement allows simpler implementation of OpenMP around the whole of the aerosol subsystem and gives close to ideal speed up. Applying a dynamic schedule or retaining a simpler static schedule for the OpenMP parallel loop are shown to differ related to the number of threads.