Horizontal Resolution Dependence of Atmospheric Simulations of the Fukushima Nuclear Accident Using 15-km, 3-km, and 500-m Grid Models
Horizontal Resolution Dependence of Atmospheric Simulations of the Fukushima Nuclear Accident Using 15-km, 3-km, and 500-m Grid Models
复制标题
DOI：
10.2151/jmsj.2015-002
复制
发表时间：
2015
影响因子：
3.1
通讯作者：
T. Sekiyama;Masaru Kunii;M. Kajino;T. Shimbori
中科院分区：
文献类型：
--
作者：
T. Sekiyama;Masaru Kunii;M. Kajino;T. Shimbori
我们研究了2011年3月15日福岛核事故大气放射性核素（Cs-137）模拟的水平分辨率依赖性。我们使用了低分辨率（15公里）、中分辨率（3公里）和高分辨率（500米）的欧拉和拉格朗日输运模型；两个模式都是由我们的数据同化系统（NHM-LETKF）为每个水平分辨率准备的相同气象分析驱动的。这种准备对于依赖于分辨率的调查是必要的，不包括任何气象场的插值或平均。结果显示，15公里的网格分析无法详细再现福岛的山地地形，因此无法描绘出山脉和山谷上方复杂的风结构。事实上，2011年3月15日，从福岛第一核电站（FDNPP）排放的铯-137羽流在越过Abukuma山脉后，大部分被Azuma山和其他沿着Naka-dori山谷的山脉阻挡了。然而，15公里的网格模拟并不能代表Cs-137羽流的堵塞，它在Naka-dori山谷中不自然地扩散。相比之下，3 km和500 m网格模拟产生了非常相似的Cs-137浓度和沉积，并成功地产生了沿Naka-dori山谷的羽流阻塞和沉积。总之，当需要进行区域分析时，应该避免使用低分辨率（15公里网格或更大）的大气模型来评估福岛核事故。同时，由于3 km网格模型的相似性和500 m网格模型仿真计算量大，使用3 km网格模型代替500 m网格模型是合理的。
We investigated the horizontal resolution dependence of atmospheric radionuclide (Cs-137) simulations of the Fukushima nuclear accident on March 15, 2011. We used Eulerian and Lagrangian transport models with low(15-km), medium(3-km), and high(500-m) resolutions; both models were driven by the same meteorological analysis that was prepared by our data assimilation system (NHM-LETKF) for each horizontal resolution. This preparation was necessary for the resolution-dependent investigation, excluding any interpolation or averaging of meteorological fields. In the results, the 15-km grid analysis could not reproduce Fukushima’s mountainous topography in detail, and consequently failed to depict a complex wind structure over mountains and valleys. In reality, the Cs-137 plume emitted from the Fukushima Daiichi Nuclear Power Plant (FDNPP) was mostly blocked by Mt. Azuma and other mountains along the Naka-dori valley after crossing over Abukuma Mountains on March 15, 2011. However, the 15-km grid simulations could not represent the blockage of the Cs-137 plume, which unnaturally spread through the Naka-dori valley. In contrast, the 3-km and 500-m grid simulations produced very similar Cs-137 concentrations and depositions, and successfully produced the plume blockage and deposition along the Naka-dori valley. In conclusion, low-resolution (15-km grid or greater) atmospheric models should be avoided for assessing the Fukushima nuclear accident when a regional analysis is needed. Meanwhile, it is reasonable to use 3-km grid models instead of 500-m grid models due to their similarities and the high computational burden of 500-m grid model simulations.