Cloud-based simulation of air-quality over cities

European regulations on air-quality protection require more and more the testing and evaluation of adaptation and reduction scenarios. From the traditional evaluation of 2 to 3 scenarios, consulting companies and regional air-quality agencies are now facing the need to evaluate tens of scenarios. This requires a large increase in their capacity for computing beyond what they can easily manage with in-house resources. The result of this Fortissimo experiment is a demonstration of cloud-based-HPC services to investigate air-quality at the scale of cities. The experiment uses the ADMS-Urban software from CERC running on the Extreme Factory HPC offering from Bull. If there is no constraint on the time to produce results for a typical urban air-quality study (i.e. simulations can take 3 months or more), the cost to exploit an HPC cloud system is higher than the costs of to acquiring and maintaining an internal server. In contrast, if the time to perform a simulation is short (1 month or less), then the exploitation of a Cloud-based HPC system (using pay on demand) is economically interesting (from a factor 2 to 10 cheaper). This can result in an increased margin while offering the client a reduction of time to complete a study. Alternatively the HPC system can support additional services such as the evaluation of uncertainties or the testing of more scenarios.