Abstract The Jack Rabbit II (JR II) chlorine field trials in 2015 and 2016 involved nine 5–20 ton releases of pressurized liquefied chlorine from a tank mounted 1 m above a broad flat desert sand surface. A model comparison study was initiated, where 17 widely-used dense-gas dispersion models were run by scientists in seven countries. Predictions were submitted following specified formats, using specified emissions and meteorology inputs. To compare with the model predictions, sets of observations were defined for the arc-maximum 1–3 s averaged concentrations (arc max C) and for cloud widths and heights (to 20 ppm and 200 ppm contours) at distances from 0.2 to 11.0 km from the release. The initial focus is on the three field trials (1, 6, and 7) that have the highest observed concentrations and that have detailed emissions information. It is found that these models are able to satisfactorily simulate (generally within a factor of two) the observed arc max C's and their variation with downwind distance at this flat desert site. At each downwind distance, the scatter in the arc max C predictions covers about 1 ½ orders of magnitude, but the observed arc max C is within the range of the predictions. The median of the cloud width predictions is about 50% larger than the observed value for the three trials. The median of the cloud height predictions is within about 10% of the observed value. For both cloud width and/or height, there are a few models with large (factor of 3 or higher) overpredictions. Of the 17 models, when compared to observations, there is a core group of 5 or 6 with consistently (across all three trials and all distances) less mean error and scatter in their predictions of arc max C and cloud width and height. However, as a group, the 17 models are performing adequately (using the “factor of two” rule of thumb). An important caveat is that, at the JR II desert site, chlorine deposition is minimal. At a site with vegetation and/or organic-rich soil, the effects of removal of chlorine by deposition are expected to be significant.

中文翻译：

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将 17 个密集气体扩散模型的预测与 Jack Rabbit II 氯气现场实验的观察结果进行比较的结果

摘要 2015 年和 2016 年的 Jack Rabbit II (JR II) 氯气现场试验涉及从安装在宽阔平坦沙漠沙面上方 1 m 处的储罐中释放 9 次 5-20 吨的加压液化氯气。启动了模型比较研究，其中 7 个国家的科学家运行了 17 个广泛使用的稠密气体扩散模型。预测是按照指定的格式提交的，使用指定的排放和气象输入。为了与模型预测进行比较，为 0.2 至 11.0 公里距离处的弧最大 1-3 秒平均浓度（弧最大 C）和云的宽度和高度（至 20 ppm 和 200 ppm 等值线）定义了一组观测值从发布。最初的重点是三个现场试验（1、6 和 7），它们具有最高的观测浓度和详细的排放信息。发现这些模型能够令人满意地模拟（通常在两倍以内）在这个平坦的沙漠地点观测到的弧最大 C 及其随顺风距离的变化。在每个顺风距离处，弧最大 C 预测的散布覆盖大约 1.5 个数量级，但观察到的弧最大 C 在预测范围内。云宽度预测的中位数比三个试验的观察值大约 50%。云高预测的中值在观测值的大约 10% 以内。对于云的宽度和/或高度，有一些模型具有较大的（因子为 3 或更高）高估。在 17 个模型中，与观测值相比，有一个由 5 或 6 人组成的核心小组，在他们对弧最大 C 和云的宽度和高度的预测中，始终（在所有三个试验和所有距离中）平均误差和分散性较小。然而，作为一个整体，这 17 个模型表现良好（使用“二倍”经验法则）。一个重要的警告是，在 JR II 沙漠场地，氯沉积最少。在有植被和/或富含有机物的土壤的地点，通过沉积去除氯的效果预计会很显着。