The HECToR Service is now closed and has been superceded by ARCHER.

Cloud and Aerosol Research on Massively-parallel Architectures (CARMA)

The UK Met Office Large Eddy Model (LEM) is an idealised model for cloud-scale microphysical studies. The LEM is used at the Universities of Leeds and Manchester for many NERC / NCAS funded projects (e.g. COPS, APPRAISE-ICE, ICEPIC) and also in conjunction with the Aerosol-Cloud-Precipitation Interaction Model (ACPIM) to study cloud scale and microscale processes. These simulations are used to investigate important effects on global circulations, such as aerosol-cloud interactions (with the help of other models and laboratory data) and thunderstorm electrification. However, the dynamical core of the applications limit usability to small domain sizes, and restrict the use of forced boundary conditions or nesting.

ACPIM has a modular framework and has been developed and validated at the University of Manchester and at the Institute for Meteorology and Climate research in Germany. ACPIM's is primarily used as a detailed process-scale model for studying the growth and evolution of cloud from aerosols but also with laboratory data as a validation tool for developing parameterisations for use in the LEM. ACPIM can be run from either prescribed wind fields, or driven by wind fields from the LEM.

The LEM and ACPIM models work in synergy to improve our understanding of the impacts of micro-scale processes on the evolution and life-cycle of clouds. The aim of this dCSE project is to improve the computational efficiency and operation of these two key numerical cloud models that are of significant importance to the UK atmospheric science community. This will be achieved by:

  • Updating the parallel iterative pressure solver within the LEM to improve the efficiency of the LEM on HECToR.
  • Developing a parallel implementation of ACPIM for use on HECToR in order to enable more realistic parameterisation of the models.

The achievements of the project are summarised below:

  • A major improvement to the pressure solver in the LEM was implemented by replacing the original Fast Fourier Transform method which required periodic boundary conditions, with the Jacobi-preconditioned bi-conjugate gradient method.
  • This newly implemented iterative solver has been fully tested with a one dimensional data decomposition and validated from known solutions.

Please see PDF or HTML for a report which summarises this project.