Institute of Methodologies for Environmental Analysis (IMAA), Italian Research Council (CNR), 85050 Tito Scalo (PZ), Italy.
Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, PA 15260, USA.
Sensors (Basel). 2021 Feb 23;21(4):1538. doi: 10.3390/s21041538.
The Normalized Hotspot Indices (NHI) tool is a Google Earth Engine (GEE)-App developed to investigate and map worldwide volcanic thermal anomalies in daylight conditions, using shortwave infrared (SWIR) and near infrared (NIR) data from the Multispectral Instrument (MSI) and the Operational Land Imager (OLI), respectively, onboard the Sentinel 2 and Landsat 8 satellites. The NHI tool offers the possibility of ingesting data from other sensors. In this direction, we tested the NHI algorithm for the first time on Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. In this study, we show the results of this preliminary implementation, achieved investigating the Kilauea (Hawaii, USA), Klyuchevskoy (Kamchatka; Russia), Shishaldin (Alaska; USA), and Telica (Nicaragua) thermal activities of March 2000-2008. We assessed the NHI detections through comparison with the ASTER Volcano Archive (AVA), the manual inspection of satellite imagery, and the information from volcanological reports. Results show that NHI integrated the AVA observations, with a percentage of unique thermal anomaly detections ranging between 8.8% (at Kilauea) and 100% (at Shishaldin). These results demonstrate the successful NHI exportability to ASTER data acquired before the failure of SWIR subsystem. The full ingestion of the ASTER data collection, available in GEE, within the NHI tool allows us to develop a suite of multi-platform satellite observations, including thermal anomaly products from Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+), which could support the investigation of active volcanoes from space, complementing information from other systems.
归一化热点指数 (NHI) 工具是一个 Google Earth Engine (GEE) 应用程序，用于利用多光谱仪 (MSI) 的短波红外 (SWIR) 和近红外 (NIR) 数据以及 Sentinel 2 和 Landsat 8 卫星上的操作陆地成像仪 (OLI) ，在白天条件下调查和绘制全球火山热异常图。NHI 工具提供了摄取其他传感器数据的可能性。在这方面，我们首次在高级星载热发射和反射辐射计 (ASTER) 数据上测试了 NHI 算法。在本研究中，我们展示了通过调查 2000 年 3 月至 2008 年期间的基拉韦厄（美国夏威夷）、克利夫斯克沃伊（俄罗斯堪察加半岛）、希什达尔丁（美国阿拉斯加）和泰利卡（尼加拉瓜）火山活动，实现这一初步实现的结果。我们通过与 ASTER 火山档案 (AVA) 、卫星图像的手动检查以及火山学报告中的信息进行比较，评估了 NHI 的检测结果。结果表明，NHI 集成了 AVA 观测结果，独特热异常检测的百分比在基拉韦厄为 8.8%（在基拉韦厄）和 100%（在希什达尔丁）之间。这些结果证明了 NHI 成功地可用于在 SWIR 子系统故障之前获取的 ASTER 数据。在 NHI 工具中完全摄取 GEE 中可用的 ASTER 数据集，使我们能够开发一套多平台卫星观测套件，包括来自 Landsat 专题制图仪 (TM) 和增强型专题制图仪加 (ETM+) 的热异常产品，这些产品可以支持从太空调查活火山，补充来自其他系统的信息。
