applications


Climate,clusters, and cooperation


Robert Roe investigates the use of collaboration and open source programming models to drive computational modelling of weather and climate research


T


he complexity and scale of weather and climate simulation have led weather centres and research groups to turn to their own community, either through


direct collaboration or open source soſtware initiatives, to increase performance and usability of these hugely complex models. At the Barcelona Supercomputing Centre


in Spain, one model, called Caliope, helps researchers forecast air quality using a combination of different models that have all been unified into this single piece of soſtware. Caliope consists of a model for emissions (Hermesv2), a meteorological model (WRF- ARW v3.5.1), a chemical transport model (CMAQ v5.0.2), and a mineral dust atmospheric model (BSC-Dream8bv). Kim Serradell, co-leader of the Computer


Earth Sciences group (CES) at the BSC, stated: ‘All of these systems we are applying in six different domains. We go from the coarse domain of Europe at a resolution of 30 kilometres, and then we are doing nesting from Europe to the peninsula Iberica. We are very interested in running these models on the European scale at 1 kilometre. We are running at that scale in Barcelona, Madrid, and also the south of the peninsula’. All of this work creates a huge demand for computational resources, which is why many


www.scientific-computing.com l


of these centres need their own HPC cluster. At the end of 2014, the UK’s Met Office announced that it would purchase one such cluster and has awarded a 4 year contract valued at around £97 million to Cray for its next HPC and storage system. To get an idea of the scale, this was the largest single order that Cray had received outside of the USA. Per Nyberg, director of business development


at Cray sees such investment as a continuation of a trend towards a realisation of the true value in this kind of research. Huge sums of money can be saved through accurate disaster protection, but


‘WE NEED SOLUTIONS


THAT ARE APPLICABLE ALL ACROSS EUROPE’


regular forecasting of weather and air pollution are equally important services provided through these centres. Nyberg said: ‘One of the main drivers for


all of this spending is the impact on society and economies around the world. I have been working with weather centres for around two and a half decades now; that area of looking at an ROI and looking at it as a business case for these investments – that is something that has really become prominent only in the last few years.’


@scwmagazine


Resilience and redundancy Nyberg continued: ‘When you look at the models themselves, or the forecast products or deliverables, maybe you are looking at hyperlocal precipitation to forecast flood warnings, for example. You need to be at a spatial resolution that is very fine, and then you also obviously have a need to deliver that product as quickly as possible.’ Delivering these regular forecasts at increasing


resolutions or with integrated models providing a more comprehensive view of the physics involved, increases computational demand considerably. For operational centres like the Met Office this task is made more difficult as it cannot afford even a small amount of downtime. Nyberg explained that, to overcome these challenges, resiliency and redundancy must be built into the initial contract requirements. Nyberg said: ‘One critical aspect of this is


that it is a multi-year contract, and that is quite typical for the larger weather services. Ultimately, what you are delivering is a weather forecasting capability over time.’ ‘It is almost standard now, at all of the main


weather services, that they have two different and essentially mirrored systems that share a single pool of storage, so that you can switch over very quickly. Some mirroring goes on there also, mainly operational data, in case there is some


JUNE/JULY 2015 47


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