UKCA GPU port ============= The `United Kingdom Chemistry and Aerosols (UKCA) `__ model is the UK's community atmospheric chemistry model. It is written in Fortran and has been developed by contributors from several research groups and institutions (notably the Met Office, University of Cambridge, and University of Leeds) over several decades. It is a core part of the Met Office's operational weather model and the `United Kingdom Earth System Model (UKESM) `__, which has contributed to `Coupled Model Inter-comparison Project (CMIP) `__ climate modelling iterations, whose data support `IPCC `__ reports. `PSyclone `__ is a Python-based domain-specific compiler and code transformation system for Earth-system models written in Fortran. It plays a key role in the Met Office's next-generation weather model `LFRic `__ and can be used to transform code according to user-provided transformation specifications. Main contribution 1 ^^^^^^^^^^^^^^^^^^^ Whilst a Scientific Software Engineer (SSE) at the Met Office, I was deployed on the GPU port for UKCA. UKCA is known to be a particularly computationally costly part of the Met Office's model, making it a key candidate for acceleration via GPU offloading. Early in the project, I worked with collaborators to first manually insert `OpenACC `__ pragmas for offloading on Nvidia GPUs. Facilitating this also involved major code changes and refactoring. Later in the project, I led the effort to replicate the manual insertion of OpenACC pragmas using PSyclone, to improve portability of the GPU porting approach. To achieve this, I developed an internal tool for streamlining OpenACC GPU porting with PSyclone, which I have since upstreamed into PSyclone itself. Project information 1 """"""""""""""""""""" My work as an SSE at the Met Office received funding from the UK's `ExCALIBUR `__ exascale computing grant. Main contribution 2 ^^^^^^^^^^^^^^^^^^^ Upon joining the University of Cambridge as an RSE, I was deployed part-time onto the follow-up project, NG-ARCH, which was outsourced to several UK universities by the Met Office. The focus of this work is to build upon the ExCALIBUR effort and work to get the approach merged into the main codebase. I continue to make regular contributions to both UKCA and PSyclone. Project information 2 """"""""""""""""""""" The NG-ARCH project is part of the Met Office's `Next-Generation Modelling Systems (NGMS) `__ programme.