Orographic effects on the transport and deposition of volcanic ash: A case study of Mount Sakurajima, Japan
Orographic effects on the transport and deposition of volcanic ash: A case study of Mount Sakurajima, Japan
复制标题
地形对火山灰迁移和沉积的影响：以日本樱岛山为例
DOI：
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
I. Renfrew
中科院分区：
文献类型：
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作者：
A. Poulidis;T. Takemi;M. Iguchi;I. Renfrew
火山灰是一种主要的大气危害，对当地居民和国际航空产生重大影响。火山周围的地形会影响火山灰的输送和沉积，但这些影响尚未得到深入研究。在这里，我们使用天气研究和预报模型的化学解析版本，研究了日本樱岛火山背景下地形对火山灰输送和沉积的影响。樱岛周围山地地形，火山喷发频繁，观测网络完善，是进行此类研究的理想地点。在樱岛，数值实验表明，在 2-8Φ 粒度范围内，“中等尺寸”灰烬 (3-5Φ) 的沉积最容易受到地形流的影响。解决细尺度地形现象的直接影响是抵消的：山脉引起的大气重力波可以使火山灰漂浮，而山背风处增强的下坡风（强达 50%）可以迫使火山灰向下移动。重力波和下坡风被认为沿着火山和其他山脉附近的扩散路径产生影响。根据大气条件，解决这些地形影响意味着火山灰可以在喷发后不久（20 分钟内）和靠近喷口（前 10 公里内）输送到高于初始喷射高度（尤其是细于 2 的火山灰），从而有效地修改火山灰扩散模型中使用的输入羽流高度，这种效应在初始化模拟时应考虑在内。
Volcanic ash is a major atmospheric hazard that has a significant impact on local populations and international aviation. The topography surrounding a volcano affects the transport and deposition of volcanic ash, but these effects have not been studied in depth. Here we investigate orographic impacts on ash transport and deposition in the context of the Sakurajima volcano in Japan, using the chemistry‐resolving version of the Weather Research and Forecasting model. Sakurajima is an ideal location for such a study because of the surrounding mountainous topography, frequent eruptions, and comprehensive observing network. At Sakurajima, numerical experiments reveal that across the 2–8ϕ grain size range, the deposition of “medium‐sized” ash (3–5ϕ) is most readily affected by orographic flows. The direct effects of resolving fine‐scale orographic phenomena are counteracting: mountain‐induced atmospheric gravity waves can keep ash afloat, while enhanced downslope winds in the lee of mountains (up to 50% stronger) can force the ash downward. Gravity waves and downslope winds were seen to have an effect along the dispersal path, in the vicinity of both the volcano and other mountains. Depending on the atmospheric conditions, resolving these orographic effects means that ash can be transported higher than the initial injection height (especially for ash finer than 2ϕ), shortly after the eruption (within 20 min) and close to the vent (within the first 10 km), effectively modifying the input plume height used in an ash dispersal model—an effect that should be taken into account when initializing simulations.
影响因子：
5.8
作者：
Manzella, Irene;Bonadonna, Costanza;Monnard, Helene
通讯作者：
Monnard, Helene
云朵飘过小安的列斯群岛
影响因子：
3.2
作者：
Kirshbaum D
通讯作者：
Kirshbaum D
影响因子：
3.5
作者：
Bonadonna, Costanza;Folch, Arnau;Puempel, Herbert
通讯作者：
Puempel, Herbert