Comparison of the predictive results from the two dispersion models PUMA and LPELLO with the JR II field data

摘要

Events triggered by unfortunate accidents or malicious antagonistic attacks bear witness to the great health risks involved in sudden releases of poisonous liquefied gases. For the society to be better prepared for these types of crises, experimental data from controlled releases is essential. To address this, a set of large scale releases of chlorine gas was conducted in the Jack Rabbit II field trials. The resulting dense gas plumes were monitored at distances up to 11 km by means of a comprising network of sensors. A group of international researchers involved in atmospheric dispersion modelling was formed to reproduce the field trials with different models as a benchmarking process to collectively improve upon the model suite and, in the end, be able to provide enhanced support to the society. The Swedish Defence Research Agency has previously developed two custom-made models for atmospheric dispersion on the local scale: PUMA and LPELLO. They use different modelling schemes but are able to handle the same types of dispersion processes. The validation process presented in this study was based on three selected field trials from Jack Rabbit II. Necessary meteorology and source data was, with some simplifications, congregated and distributed by the organizers to obtain a high degree of uniformity in the input data for the different models. Simulations were conducted by replicating these prerequisites whereby the resulting concentration plumes were analysed and compared with the measured data. There are many different metrics, properties and phenomena to scrutinize in a model validation process. After a thorough analysis, it was found that the two models showed similar plume behaviours in some aspects but also possessed quite diverse characteristics in others. In particular, the simulated concentration maxima were in general higher than the measurements indicate, which is analysed and discussed in detail. Findings and analyses presented here will have bearing on other dispersion models using similar schemes.