National Meteorological Satellite Center (NMSC), Korea Meteorological Administration (KMA), Jincheon-gun 27803, Korea.
Research Center for Atmospheric Environment, Hankuk University of Foreign Studies, Yongin 17035, Korea.
Sensors (Basel). 2021 Feb 15;21(4):1359. doi: 10.3390/s21041359.
In this study, a technique facilitating the enhanced detection of airborne volcanic ash (VA) has been developed, which is based on the use of visible (VIS), near-infrared (NIR), and infrared (IR) bands by meteorological satellite systems. Channels with NIR and IR bands centered at ~3.8, 7.3, 8.7, 10.5, and 12.3 μm are utilized, which enhances the accuracy of VA detection. The technique is based on two-band brightness temperature differences (BTDs), two-band brightness temperature ratios (BTRs), and background image BTDs. The physical effects of the observed BTDs and BTRs, which can be used to distinguish VA from meteorological clouds based on absorption differences, depend on the channel and time of day. The Advanced Meteorological Imager onboard the GEOKOMPSAT-2A (GK-2A) satellite has several advantages, including the day- and nighttime detection of land and ocean. Based on the GK-2A data on several volcanic eruptions, multispectral data are more sensitive to volcanic clouds than ice and water clouds, ensuring the detection of VA. They can also be used as an input to provide detailed information about volcanoes, such as the height of the VA layer and VA mass. The GK-2A was optimized, and an improved ash algorithm was established by focusing on the volcanic eruptions that occurred in 2020. In particular, the 3.8 μm band was utilized, the threshold was changed by division between day and night, and efforts were made to reduce the effects of clouds and the discontinuity between land and ocean. The GK-2A imagery was used to study volcanic clouds related to the eruptions of Taal, Philippines, on 12 January and Nishinoshima, Japan, from 30 July-2 August to demonstrate the applicability of this product during volcanic events. The improved VA product of GK-2A provides vital information, helping forecasters to locate VA as well as guidance for the aviation industry in preventing dangerous and expensive interactions between aircrafts and VA.
在这项研究中，开发了一种利用气象卫星系统的可见（VIS）、近红外（NIR）和红外（IR）波段来增强探测空气传播火山灰（VA）的技术。该技术利用了中心波长在~3.8、7.3、8.7、10.5 和 12.3 μm 的 NIR 和 IR 波段的通道，从而提高了 VA 探测的准确性。该技术基于两波段亮度温度差（BTD）、两波段亮度温度比（BTR）和背景图像 BTD。观测 BTD 和 BTR 的物理效应可用于根据吸收差异区分 VA 和气象云，其取决于通道和一天中的时间。GEOKOMPSAT-2A（GK-2A）卫星上的高级气象成像仪具有许多优势，包括陆地和海洋的昼夜探测。基于 GK-2A 对几次火山喷发的多光谱数据，与冰云和水云相比，多光谱数据对火山云更敏感，从而确保了 VA 的探测。它们还可以作为输入，提供有关火山的详细信息，例如 VA 层的高度和 VA 质量。对 GK-2A 进行了优化，并通过专注于 2020 年发生的火山喷发，建立了改进的火山灰算法。特别是利用了 3.8 μm 波段，通过昼夜划分改变了阈值，并努力减少云的影响以及陆地和海洋之间的不连续性。利用 GK-2A 图像研究了与菲律宾塔尔火山喷发以及日本西之岛火山喷发相关的火山云，以展示该产品在火山事件中的适用性。GK-2A 的改进 VA 产品提供了重要信息，帮助预报员定位 VA 并为航空业提供指导，以防止飞机与 VA 之间发生危险和昂贵的相互作用。
