High Performance Computing Case Study - Dr Manoj Joshi

Lecturer - School of Environmental Sciences

My research is about understanding climate and climate change, mostly on Earth, but also on other planets. To further this aim, I use a combination of theory and models, ranging from simple numerical codes to very complex global circulation models.

The benefits of using Grace for High Performance Computing

The models used run on dozens of processors, enabling century-scale integrations of the climate in a matter of hours to days, enabling a step-change in the science that I can do with it. Without the fast interconnected parallel facility, the model would run far more slowly, keeping lots of science questions out of reach.

Using grace rather than a remote HPC - it's a local machine which means fast access, access to the local filestore when needed and a local support team who I can talk to if all else fails.

My work

An intermediate global circulation model is now running on grace, taking advantage of the parallel architecture. The reason for using "intermediate" models is that they provide an excellent and flexible framework for understanding climate and complement both theory and the more complex state-of-the-art climate models which are far more computationally expensive.

An example of this work is an experimental high-resolution version of the intermediate global circulation model. The movie loop  (beware - 10MB do not view on slow network connections) shows surface brightness (in white), clouds (in shades of grey) and rainfall (in colours) evolving over 3 months in Northern winter. The Greenwich meridian lies on the extreme left and right hand sides, with the dateline in the centre.

Weather systems, and their associated rainfall and clouds, can be seen moving from left to right (eastwards) in the southern and northern extratropics, while tropical weather systems move slowly from right to left (westwards). Snow cover can be seen over northern Eurasia (top left), North America (top centre-right) and over Antarctica (bottom). A few tropical cyclones are generated: these are almost circular blobs which are coloured orange (denoting very high rainfall), and slowly move westwards in the tropics before pulled into the extratropical eastward flow.