Ash from Kilauea Eruption Viewed by NASA's MISR 基拉韦厄火山喷发灰烬

Editor: Tony Greicius

On May 3, 2018, a new eruption began at a fissure of the Kilauea volcano on the Island of Hawaii. Kilauea is the most active volcano in the world, having erupted almost continuously since 1983. Advancing lava and dangerous sulfur dioxide gas have forced thousands of residents in the neighborhood of Leilani Estates to evacuate. A number of homes have been destroyed, and no one can say how soon the eruption will abate and evacuees can return home.

On May 6, 2018, at approximately 11 a.m. local time, the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra satellite captured this view of the island as it passed overhead. Much of the island was shrouded by clouds, including the fissure on its eastern point. However, an eruption plume is visible streaming southwest over the ocean. The MISR instrument is unique in that it has nine cameras that view Earth at different angles: one pointing downward, four at various angles in the forward direction, and four in the backward direction. This image shows the view from one of MISR's forward-pointing cameras (60 degrees), which shows the plume more distinctly than the near-vertical views.

The information from the images acquired at different view angles is used to calculate the height of the plume, results of which are superimposed on the right-hand image. The top of the plume near the fissure is at approximately 6,500 feet (2,000 meters) altitude, and the height of the plume decreases as it travels south and west. These relatively low altitudes mean that the ash and sulfur dioxide remained near the ground, which can cause health issues for people on the island downwind of the eruption. The "Ocean View" air quality monitor operated by the Clean Air Branch of the State of Hawaii Department of Health recorded a concentration of 18 μg/m3 of airborne particles less than 2.5 micrometers in diameter at 11 a.m. local time. This amount corresponds to an air quality rating of "moderate" and supports the MISR results indicating that ash was most likely present at ground level on this side of the island.

These data were acquired during Terra orbit 97780. The smoke plume height calculation was performed using the MISR INteractive eXplorer (MINX) software tool, which is publicly available at https://github.com/nasa/MINX. The MISR Plume Height Project maintains a database of global smoke plume heights, accessible at https://www-misr.jpl.nasa.gov/getData/accessData/MisrMinxPlumes2/.

MISR was built and is managed by NASA's Jet Propulsion Laboratory in Pasadena, California, for NASA's Science Mission Directorate in Washington. The Terra spacecraft is managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland. The MISR data were obtained from the NASA Langley Research Center Atmospheric Science Data Center in Hampton, Virginia. JPL is a division of Caltech in Pasadena.

2018年5月3日，夏威夷大岛基拉韦厄火山的裂缝开始了新的喷发。基拉韦厄火山是世界上最活跃的火山，自 1983 年以来几乎连续喷发。前进的熔岩和危险的二氧化硫气体迫使莱拉尼庄园附近的数千名居民撤离。许多房屋已被摧毁，没有人能说喷发多久会减弱，撤离人员可以返回家园。

2018年5月6日，当地时间上午 11 点左右，美国宇航局 Terra 卫星上的多角度成像光谱辐射计 (MISR) 仪器在岛屿经过头顶时捕捉到了这张岛屿的景色。岛上的大部分地区都被云层笼罩，包括东端的裂缝。然而，可以看到一股喷发羽流在海洋的西南方向流动。 MISR仪器的独特之处在于它有九个以不同角度观察地球的相机：一个指向下方，四个向前方向的不同角度，四个向后方向。这张图片显示了 MISR 的一个前向摄像机（60度）的视图，它比近乎垂直的视图更清楚地显示了羽流。

从不同视角获取的图像信息用于计算羽流的高度，其结果叠加在右侧图像上。靠近裂缝的羽流顶部大约在6,500英尺（2,000米）的高度，随着羽流向南和向西移动，其高度会降低。这些相对较低的海拔意味着火山灰和二氧化硫留在地面附近，这可能会给火山喷发顺风岛上的人们带来健康问题。夏威夷州卫生部清洁空气分部运营的“海洋景观”空气质量监测仪在当地时间上午 11 点记录到空气中直径小于 2.5 微米的颗粒物浓度为 18 微克/立方米。这一数量对应于“中等”的空气质量等级，并支持 MISR 结果表明灰烬最有可能出现在岛屿这一侧的地面上。

这些数据是在 Terra 轨道 97780 期间获得的。烟羽高度计算是使用 MISR INteractive eXplorer (MINX) 软件工具进行的，该工具可在 https://github.com/nasa/MINX 上公开获得。 MISR 羽流高度项目维护一个全球烟羽高度数据库，可在 https://www-misr.jpl.nasa.gov/getData/accessData/MisrMinxPlumes2/ 访问。

MISR 由位于加利福尼亚州帕萨迪纳的 NASA 喷气推进实验室为位于华盛顿的 NASA 科学任务理事会建造和管理。Terra宇宙飞船由位于马里兰州格林贝尔特的美国宇航局戈达德太空飞行中心管理。MISR 数据来自位于弗吉尼亚州汉普顿的美国宇航局兰利研究中心大气科学数据中心。JPL 是加州理工学院在帕萨迪纳的一个部门。